diff --git a/nac3artiq/src/lib.rs b/nac3artiq/src/lib.rs
index 0b70b6d7a..30d439e4a 100644
--- a/nac3artiq/src/lib.rs
+++ b/nac3artiq/src/lib.rs
@@ -374,7 +374,7 @@ impl Nac3 {
                 });
 
             let (name, def_id, ty) = composer
-                .register_top_level(stmt.clone(), Some(resolver.clone()), path.clone(), false)
+                .register_top_level(stmt.clone(), Some(resolver.clone()), path, false)
                 .map_err(|e| {
                     CompileError::new_err(format!(
                         "compilation failed\n----------\n{}",
@@ -596,7 +596,7 @@ impl Nac3 {
                 threads,
                 top_level.clone(),
                 &self.llvm_options,
-                f
+                &f
             );
             registry.add_task(task);
             registry.wait_tasks_complete(handles);
diff --git a/nac3core/build.rs b/nac3core/build.rs
index f7e7e92df..281e28325 100644
--- a/nac3core/build.rs
+++ b/nac3core/build.rs
@@ -9,15 +9,11 @@ use std::{
 
 fn main() {
     const FILE: &str = "src/codegen/irrt/irrt.c";
-    println!("cargo:rerun-if-changed={}", FILE);
-    let out_dir = env::var("OUT_DIR").unwrap();
-    let out_path = Path::new(&out_dir);
 
     /*
      * HACK: Sadly, clang doesn't let us emit generic LLVM bitcode.
      * Compiling for WASM32 and filtering the output with regex is the closest we can get.
      */
-
     const FLAG: &[&str] = &[
         "--target=wasm32",
         FILE,
@@ -29,6 +25,11 @@ fn main() {
         "-o",
         "-",
     ];
+
+    println!("cargo:rerun-if-changed={FILE}");
+    let out_dir = env::var("OUT_DIR").unwrap();
+    let out_path = Path::new(&out_dir);
+
     let output = Command::new("clang-irrt")
         .args(FLAG)
         .output()
@@ -68,5 +69,5 @@ fn main() {
         .spawn()
         .unwrap();
     llvm_as.stdin.as_mut().unwrap().write_all(filtered_output.as_bytes()).unwrap();
-    assert!(llvm_as.wait().unwrap().success())
+    assert!(llvm_as.wait().unwrap().success());
 }
diff --git a/nac3core/src/codegen/concrete_type.rs b/nac3core/src/codegen/concrete_type.rs
index f3f619d42..9181a1cad 100644
--- a/nac3core/src/codegen/concrete_type.rs
+++ b/nac3core/src/codegen/concrete_type.rs
@@ -63,6 +63,7 @@ pub enum ConcreteTypeEnum {
 }
 
 impl ConcreteTypeStore {
+    #[must_use]
     pub fn new() -> ConcreteTypeStore {
         ConcreteTypeStore {
             store: vec![
@@ -80,6 +81,7 @@ impl ConcreteTypeStore {
         }
     }
 
+    #[must_use]
     pub fn get(&self, cty: ConcreteType) -> &ConcreteTypeEnum {
         &self.store[cty.0]
     }
diff --git a/nac3core/src/codegen/expr.rs b/nac3core/src/codegen/expr.rs
index 88d68f7ff..6615a696d 100644
--- a/nac3core/src/codegen/expr.rs
+++ b/nac3core/src/codegen/expr.rs
@@ -47,7 +47,7 @@ pub fn get_subst_key(
         })
         .unwrap_or_default();
     vars.extend(fun_vars.iter());
-    let sorted = vars.keys().filter(|id| filter.map(|v| v.contains(id)).unwrap_or(true)).sorted();
+    let sorted = vars.keys().filter(|id| filter.map_or(true, |v| v.contains(id))).sorted();
     sorted
         .map(|id| {
             unifier.internal_stringify(
@@ -119,7 +119,7 @@ impl<'ctx, 'a> CodeGenContext<'ctx, 'a> {
             }
             SymbolValue::Tuple(ls) => {
                 let vals = ls.iter().map(|v| self.gen_symbol_val(generator, v, ty)).collect_vec();
-                let fields = vals.iter().map(|v| v.get_type()).collect_vec();
+                let fields = vals.iter().map(BasicValueEnum::get_type).collect_vec();
                 let ty = self.ctx.struct_type(&fields, false);
                 let ptr = gen_var(self, ty.into(), Some("tuple")).unwrap();
                 let zero = self.ctx.i32_type().const_zero();
@@ -165,7 +165,7 @@ impl<'ctx, 'a> CodeGenContext<'ctx, 'a> {
         }
     }
 
-    /// See [get_llvm_type].
+    /// See [`get_llvm_type`].
     pub fn get_llvm_type(
         &mut self,
         generator: &mut dyn CodeGenerator,
@@ -183,7 +183,7 @@ impl<'ctx, 'a> CodeGenContext<'ctx, 'a> {
         )
     }
 
-    /// See [get_llvm_abi_type].
+    /// See [`get_llvm_abi_type`].
     pub fn get_llvm_abi_type(
         &mut self,
         generator: &mut dyn CodeGenerator,
@@ -212,7 +212,7 @@ impl<'ctx, 'a> CodeGenContext<'ctx, 'a> {
             Constant::Bool(v) => {
                 assert!(self.unifier.unioned(ty, self.primitives.bool));
                 let ty = self.ctx.i8_type();
-                Some(ty.const_int(if *v { 1 } else { 0 }, false).into())
+                Some(ty.const_int(u64::from(*v), false).into())
             }
             Constant::Int(val) => {
                 let ty = if self.unifier.unioned(ty, self.primitives.int32)
@@ -290,12 +290,9 @@ impl<'ctx, 'a> CodeGenContext<'ctx, 'a> {
         rhs: BasicValueEnum<'ctx>,
         signed: bool
     ) -> BasicValueEnum<'ctx> {
-        let (lhs, rhs) =
-            if let (BasicValueEnum::IntValue(lhs), BasicValueEnum::IntValue(rhs)) = (lhs, rhs) {
-                (lhs, rhs)
-            } else {
-                unreachable!()
-            };
+        let (BasicValueEnum::IntValue(lhs), BasicValueEnum::IntValue(rhs)) = (lhs, rhs) else {
+            unreachable!()
+        };
         let float = self.ctx.f64_type();
         match (op, signed) {
             (Operator::Add, _) => self.builder.build_int_add(lhs, rhs, "add").into(),
@@ -318,7 +315,7 @@ impl<'ctx, 'a> CodeGenContext<'ctx, 'a> {
             (Operator::BitAnd, _) => self.builder.build_and(lhs, rhs, "and").into(),
 
             // Sign-ness of bitshift operators are always determined by the left operand
-            (Operator::LShift, signed) | (Operator::RShift, signed) => {
+            (Operator::LShift | Operator::RShift, signed) => {
                 // RHS operand is always 32 bits
                 assert_eq!(rhs.get_type().get_bit_width(), 32);
 
@@ -365,11 +362,7 @@ impl<'ctx, 'a> CodeGenContext<'ctx, 'a> {
         lhs: BasicValueEnum<'ctx>,
         rhs: BasicValueEnum<'ctx>,
     ) -> BasicValueEnum<'ctx> {
-        let (lhs, rhs) = if let (BasicValueEnum::FloatValue(lhs), BasicValueEnum::FloatValue(rhs)) =
-            (lhs, rhs)
-        {
-            (lhs, rhs)
-        } else {
+        let (BasicValueEnum::FloatValue(lhs), BasicValueEnum::FloatValue(rhs)) = (lhs, rhs) else {
             unreachable!()
         };
         let float = self.ctx.f64_type();
@@ -474,7 +467,7 @@ impl<'ctx, 'a> CodeGenContext<'ctx, 'a> {
             .collect_vec();
         let result = if let Some(target) = self.unwind_target {
             let current = self.builder.get_insert_block().unwrap().get_parent().unwrap();
-            let then_block = self.ctx.append_basic_block(current, &format!("after.{}", call_name));
+            let then_block = self.ctx.append_basic_block(current, &format!("after.{call_name}"));
             let result = self
                 .builder
                 .build_invoke(fun, &params, then_block, target, call_name)
@@ -516,7 +509,7 @@ impl<'ctx, 'a> CodeGenContext<'ctx, 'a> {
             let ty = self.get_llvm_type(generator, self.primitives.exception).into_pointer_type();
             let zelf_ty: BasicTypeEnum = ty.get_element_type().into_struct_type().into();
             let zelf = generator.gen_var_alloc(self, zelf_ty, Some("exn")).unwrap();
-            self.exception_val.insert(zelf).to_owned()
+            *self.exception_val.insert(zelf)
         };
         let int32 = self.ctx.i32_type();
         let zero = int32.const_zero();
@@ -556,7 +549,7 @@ impl<'ctx, 'a> CodeGenContext<'ctx, 'a> {
         loc: Location,
     ) {
         let err_msg = self.gen_string(generator, err_msg);
-        self.make_assert_impl(generator, cond, err_name, err_msg, params, loc)
+        self.make_assert_impl(generator, cond, err_name, err_msg, params, loc);
     }
 
     pub fn make_assert_impl(
@@ -598,7 +591,7 @@ impl<'ctx, 'a> CodeGenContext<'ctx, 'a> {
     }
 }
 
-/// See [CodeGenerator::gen_constructor].
+/// See [`CodeGenerator::gen_constructor`].
 pub fn gen_constructor<'ctx, 'a, G: CodeGenerator>(
     generator: &mut G,
     ctx: &mut CodeGenContext<'ctx, 'a>,
@@ -626,14 +619,14 @@ pub fn gen_constructor<'ctx, 'a, G: CodeGenerator>(
             }
             Ok(zelf)
         }
-        _ => unreachable!(),
+        TopLevelDef::Function { .. } => unreachable!(),
     }
 }
 
-/// See [CodeGenerator::gen_func_instance].
+/// See [`CodeGenerator::gen_func_instance`].
 pub fn gen_func_instance<'ctx>(
     ctx: &mut CodeGenContext<'ctx, '_>,
-    obj: Option<(Type, ValueEnum<'ctx>)>,
+    obj: &Option<(Type, ValueEnum<'ctx>)>,
     fun: (&FunSignature, &mut TopLevelDef, String),
     id: usize,
 ) -> Result<String, String> {
@@ -683,7 +676,7 @@ pub fn gen_func_instance<'ctx>(
                 args.insert(
                     0,
                     ConcreteFuncArg { name: "self".into(), ty: zelf, default_value: None },
-                )
+                );
             } else {
                 unreachable!()
             }
@@ -707,7 +700,7 @@ pub fn gen_func_instance<'ctx>(
     }
 }
 
-/// See [CodeGenerator::gen_call].
+/// See [`CodeGenerator::gen_call`].
 pub fn gen_call<'ctx, G: CodeGenerator>(
     generator: &mut G,
     ctx: &mut CodeGenContext<'ctx, '_>,
@@ -738,11 +731,11 @@ pub fn gen_call<'ctx, G: CodeGenerator>(
                 let old_key = ctx.get_subst_key(obj.as_ref().map(|a| a.0), fun.0, None);
                 let mut keys = fun.0.args.clone();
                 let mut mapping = HashMap::new();
-                for (key, value) in params.into_iter() {
+                for (key, value) in params {
                     mapping.insert(key.unwrap_or_else(|| keys.remove(0).name), value);
                 }
                 // default value handling
-                for k in keys.into_iter() {
+                for k in keys {
                     if mapping.get(&k.name).is_some() {
                         continue;
                     }
@@ -774,27 +767,26 @@ pub fn gen_call<'ctx, G: CodeGenerator>(
                         .map(|(i, v)| (*i, v.get_unique_identifier()))
                         .collect_vec();
                     let mut store = ctx.static_value_store.lock();
-                    match store.lookup.get(&ids) {
-                        Some(index) => *index,
-                        None => {
-                            let length = store.store.len();
-                            store.lookup.insert(ids, length);
-                            store.store.push(static_params.into_iter().collect());
-                            length
-                        }
+                    if let Some(index) = store.lookup.get(&ids) {
+                        *index
+                    } else {
+                        let length = store.store.len();
+                        store.lookup.insert(ids, length);
+                        store.store.push(static_params.into_iter().collect());
+                        length
                     }
                 };
                 // special case: extern functions
                 key = if instance_to_stmt.is_empty() {
-                    "".to_string()
+                    String::new()
                 } else {
-                    format!("{}:{}", id, old_key)
+                    format!("{id}:{old_key}")
                 };
                 param_vals = real_params
                     .into_iter()
                     .map(|(p, t)| p.to_basic_value_enum(ctx, generator, t))
                     .collect::<Result<Vec<_>, String>>()?;
-                instance_to_symbol.get(&key).cloned().ok_or_else(|| "".into())
+                instance_to_symbol.get(&key).cloned().ok_or_else(String::new)
             }
             TopLevelDef::Class { .. } => {
                 return Ok(Some(generator.gen_constructor(ctx, fun.0, &def, params)?))
@@ -900,7 +892,7 @@ pub fn destructure_range<'ctx>(
 /// Allocates a List structure with the given [type][ty] and [length]. The name of the resulting
 /// LLVM value is `{name}.addr`, or `list.addr` if [name] is not specified.
 ///
-/// Returns an instance of [PointerValue] pointing to the List structure. The List structure is
+/// Returns an instance of [`PointerValue`] pointing to the List structure. The List structure is
 /// defined as `type { ty*, size_t }` in LLVM, where the first element stores the pointer to the
 /// data, and the second element stores the size of the List.
 pub fn allocate_list<'ctx, G: CodeGenerator>(
@@ -1083,7 +1075,7 @@ pub fn gen_comprehension<'ctx, G: CodeGenerator>(
             ctx.builder.build_store(len_ptr, ctx.builder.build_load(index, "index"));
         };
 
-        for cond in ifs.iter() {
+        for cond in ifs {
             let result = if let Some(v) = generator.gen_expr(ctx, cond)? {
                 v.to_basic_value_enum(ctx, generator, cond.custom.unwrap())?.into_int_value()
             } else {
@@ -1226,11 +1218,11 @@ pub fn gen_binop_expr<'ctx, G: CodeGenerator>(
                 Some((left.custom.unwrap(), left_val.into())),
                 (&signature, fun_id),
                 vec![(None, right_val.into())],
-            ).map(|f| f.map(|f| f.into()))
+            ).map(|f| f.map(Into::into))
     }
 }
 
-/// See [CodeGenerator::gen_expr].
+/// See [`CodeGenerator::gen_expr`].
 pub fn gen_expr<'ctx, G: CodeGenerator>(
     generator: &mut G,
     ctx: &mut CodeGenContext<'ctx, '_>,
@@ -1462,7 +1454,7 @@ pub fn gen_expr<'ctx, G: CodeGenerator>(
                     ast::Unaryop::USub => ctx.builder.build_int_neg(val, "neg").into(),
                     ast::Unaryop::Invert => ctx.builder.build_not(val, "not").into(),
                     ast::Unaryop::Not => ctx.builder.build_xor(val, val.get_type().const_all_ones(), "not").into(),
-                    _ => val.into(),
+                    ast::Unaryop::UAdd => val.into(),
                 }
             } else if ty == ctx.primitives.float {
                 let val = val.into_float_value();
@@ -1574,11 +1566,11 @@ pub fn gen_expr<'ctx, G: CodeGenerator>(
             let test = generator.bool_to_i1(ctx, test);
             let body_ty = body.custom.unwrap();
             let is_none = ctx.unifier.get_representative(body_ty) == ctx.primitives.none;
-            let result = if !is_none {
+            let result = if is_none {
+                None
+            } else {
                 let llvm_ty = ctx.get_llvm_type(generator, body_ty);
                 Some(ctx.builder.build_alloca(llvm_ty, "if_exp_result"))
-            } else {
-                None
             };
             let current = ctx.builder.get_insert_block().unwrap().get_parent().unwrap();
             let then_bb = ctx.ctx.append_basic_block(current, "then");
@@ -1640,15 +1632,14 @@ pub fn gen_expr<'ctx, G: CodeGenerator>(
             let kw_iter = kw_iter.collect::<Result<Vec<_>, _>>()?;
             params.extend(kw_iter);
             let call = ctx.calls.get(&expr.location.into());
-            let signature = match call {
-                Some(call) => ctx.unifier.get_call_signature(*call).unwrap(),
-                None => {
-                    let ty = func.custom.unwrap();
-                    if let TypeEnum::TFunc(sign) = &*ctx.unifier.get_ty(ty) {
-                        sign.clone()
-                    } else {
-                        unreachable!()
-                    }
+            let signature = if let Some(call) = call {
+                ctx.unifier.get_call_signature(*call).unwrap()
+            } else {
+                let ty = func.custom.unwrap();
+                if let TypeEnum::TFunc(sign) = &*ctx.unifier.get_ty(ty) {
+                    sign.clone()
+                } else {
+                    unreachable!()
                 }
             };
             let func = func.as_ref();
@@ -1661,12 +1652,11 @@ pub fn gen_expr<'ctx, G: CodeGenerator>(
                         .map_err(|e| format!("{} (at {})", e, func.location))?;
                     return Ok(generator
                         .gen_call(ctx, None, (&signature, fun), params)?
-                        .map(|v| v.into()));
+                        .map(Into::into));
                 }
                 ExprKind::Attribute { value, attr, .. } => {
-                    let val = match generator.gen_expr(ctx, value)? {
-                        Some(v) => v,
-                        None => return Ok(None),
+                    let Some(val) = generator.gen_expr(ctx, value)? else {
+                        return Ok(None)
                     };
 
                     let id = if let TypeEnum::TObj { obj_id, .. } =
@@ -1745,7 +1735,7 @@ pub fn gen_expr<'ctx, G: CodeGenerator>(
                                     "unwrap_some_load"
                                 ).into()))
                             }
-                            _ => unreachable!("option must be static or ptr")
+                            ValueEnum::Dynamic(_) => unreachable!("option must be static or ptr")
                         }
                     }
 
@@ -1759,7 +1749,7 @@ pub fn gen_expr<'ctx, G: CodeGenerator>(
                             (&signature, fun_id),
                             params,
                         )?
-                        .map(|v| v.into()));
+                        .map(Into::into));
                 }
                 _ => unimplemented!(),
             }
@@ -1871,14 +1861,13 @@ pub fn gen_expr<'ctx, G: CodeGenerator>(
                         ctx.builder.build_extract_value(v, index, "tup_elem").unwrap().into()
                     }
                     Some(ValueEnum::Static(v)) => {
-                        match v.get_tuple_element(index) {
-                            Some(v) => v,
-                            None => {
-                                let tup = v
-                                    .to_basic_value_enum(ctx, generator, value.custom.unwrap())?
-                                    .into_struct_value();
-                                ctx.builder.build_extract_value(tup, index, "tup_elem").unwrap().into()
-                            }
+                        if let Some(v) = v.get_tuple_element(index) {
+                            v
+                        } else {
+                            let tup = v
+                                .to_basic_value_enum(ctx, generator, value.custom.unwrap())?
+                                .into_struct_value();
+                            ctx.builder.build_extract_value(tup, index, "tup_elem").unwrap().into()
                         }
                     }
                     None => return Ok(None),
diff --git a/nac3core/src/codegen/generator.rs b/nac3core/src/codegen/generator.rs
index ae92ab55a..7a86c0bb6 100644
--- a/nac3core/src/codegen/generator.rs
+++ b/nac3core/src/codegen/generator.rs
@@ -66,7 +66,7 @@ pub trait CodeGenerator {
         fun: (&FunSignature, &mut TopLevelDef, String),
         id: usize,
     ) -> Result<String, String> {
-        gen_func_instance(ctx, obj, fun, id)
+        gen_func_instance(ctx, &obj, fun, id)
     }
 
     /// Generate the code for an expression.
@@ -194,7 +194,7 @@ pub trait CodeGenerator {
         gen_block(self, ctx, stmts)
     }
 
-    /// See [bool_to_i1].
+    /// See [`bool_to_i1`].
     fn bool_to_i1<'ctx>(
         &self,
         ctx: &CodeGenContext<'ctx, '_>,
@@ -203,7 +203,7 @@ pub trait CodeGenerator {
         bool_to_i1(&ctx.builder, bool_value)
     }
 
-    /// See [bool_to_i8].
+    /// See [`bool_to_i8`].
     fn bool_to_i8<'ctx>(
         &self,
         ctx: &CodeGenContext<'ctx, '_>,
@@ -219,6 +219,7 @@ pub struct DefaultCodeGenerator {
 }
 
 impl DefaultCodeGenerator {
+    #[must_use]
     pub fn new(name: String, size_t: u32) -> DefaultCodeGenerator {
         assert!(matches!(size_t, 32 | 64));
         DefaultCodeGenerator { name, size_t }
@@ -227,7 +228,7 @@ impl DefaultCodeGenerator {
 
 impl CodeGenerator for DefaultCodeGenerator {
 
-    /// Returns the name for this [CodeGenerator].
+    /// Returns the name for this [`CodeGenerator`].
     fn get_name(&self) -> &str {
         &self.name
     }
diff --git a/nac3core/src/codegen/irrt/mod.rs b/nac3core/src/codegen/irrt/mod.rs
index 76e50a0d1..0cd0ebdda 100644
--- a/nac3core/src/codegen/irrt/mod.rs
+++ b/nac3core/src/codegen/irrt/mod.rs
@@ -12,6 +12,7 @@ use inkwell::{
 };
 use nac3parser::ast::Expr;
 
+#[must_use]
 pub fn load_irrt(ctx: &Context) -> Module {
     let bitcode_buf = MemoryBuffer::create_from_memory_range(
         include_bytes!(concat!(env!("OUT_DIR"), "/irrt.bc")),
@@ -288,7 +289,7 @@ pub fn handle_slice_index_bound<'ctx, G: CodeGenerator>(
 }
 
 /// This function handles 'end' **inclusively**.
-/// Order of tuples assign_idx and value_idx is ('start', 'end', 'step').
+/// Order of tuples `assign_idx` and `value_idx` is ('start', 'end', 'step').
 /// Negative index should be handled before entering this function
 pub fn list_slice_assignment<'ctx>(
     generator: &mut dyn CodeGenerator,
diff --git a/nac3core/src/codegen/mod.rs b/nac3core/src/codegen/mod.rs
index 2f4aca58f..06c0fc890 100644
--- a/nac3core/src/codegen/mod.rs
+++ b/nac3core/src/codegen/mod.rs
@@ -81,8 +81,9 @@ pub struct CodeGenTargetMachineOptions {
 
 impl CodeGenTargetMachineOptions {
 
-    /// Creates an instance of [CodeGenTargetMachineOptions] using the triple of the host machine.
+    /// Creates an instance of [`CodeGenTargetMachineOptions`] using the triple of the host machine.
     /// Other options are set to defaults.
+    #[must_use]
     pub fn from_host_triple() -> CodeGenTargetMachineOptions {
         CodeGenTargetMachineOptions {
             triple: TargetMachine::get_default_triple().as_str().to_string_lossy().into_owned(),
@@ -93,8 +94,9 @@ impl CodeGenTargetMachineOptions {
         }
     }
 
-    /// Creates an instance of [CodeGenTargetMachineOptions] using the properties of the host
+    /// Creates an instance of [`CodeGenTargetMachineOptions`] using the properties of the host
     /// machine. Other options are set to defaults.
+    #[must_use]
     pub fn from_host() -> CodeGenTargetMachineOptions {
         CodeGenTargetMachineOptions {
             cpu: TargetMachine::get_host_cpu_name().to_string(),
@@ -103,9 +105,10 @@ impl CodeGenTargetMachineOptions {
         }
     }
 
-    /// Creates a [TargetMachine] using the target options specified by this struct.
+    /// Creates a [`TargetMachine`] using the target options specified by this struct.
     ///
-    /// See [Target::create_target_machine].
+    /// See [`Target::create_target_machine`].
+    #[must_use]
     pub fn create_target_machine(
         &self,
         level: OptimizationLevel,
@@ -195,7 +198,7 @@ impl<'ctx, 'a> CodeGenContext<'ctx, 'a> {
     /// Whether the [current basic block][Builder::get_insert_block] referenced by `builder`
     /// contains a [terminator statement][BasicBlock::get_terminator].
     pub fn is_terminated(&self) -> bool {
-        self.builder.get_insert_block().and_then(|bb| bb.get_terminator()).is_some()
+        self.builder.get_insert_block().and_then(BasicBlock::get_terminator).is_some()
     }
 }
 
@@ -206,12 +209,13 @@ pub struct WithCall {
 }
 
 impl WithCall {
+    #[must_use]
     pub fn new(fp: Fp) -> WithCall {
         WithCall { fp }
     }
 
     pub fn run(&self, m: &Module) {
-        (self.fp)(m)
+        (self.fp)(m);
     }
 }
 
@@ -238,20 +242,21 @@ pub struct WorkerRegistry {
 impl WorkerRegistry {
 
     /// Creates workers for this registry.
+    #[must_use]
     pub fn create_workers<G: CodeGenerator + Send + 'static>(
         generators: Vec<Box<G>>,
         top_level_ctx: Arc<TopLevelContext>,
         llvm_options: &CodeGenLLVMOptions,
-        f: Arc<WithCall>,
+        f: &Arc<WithCall>,
     ) -> (Arc<WorkerRegistry>, Vec<thread::JoinHandle<()>>) {
         let (sender, receiver) = unbounded();
         let task_count = Mutex::new(0);
         let wait_condvar = Condvar::new();
 
         // init: 0 to be empty
-        let mut static_value_store: StaticValueStore = Default::default();
-        static_value_store.lookup.insert(Default::default(), 0);
-        static_value_store.store.push(Default::default());
+        let mut static_value_store = StaticValueStore::default();
+        static_value_store.lookup.insert(Vec::default(), 0);
+        static_value_store.store.push(HashMap::default());
 
         let registry = Arc::new(WorkerRegistry {
             sender: Arc::new(sender),
@@ -266,19 +271,19 @@ impl WorkerRegistry {
         });
 
         let mut handles = Vec::new();
-        for mut generator in generators.into_iter() {
+        for mut generator in generators {
             let registry = registry.clone();
             let registry2 = registry.clone();
             let f = f.clone();
             let handle = thread::spawn(move || {
-                registry.worker_thread(generator.as_mut(), f);
+                registry.worker_thread(generator.as_mut(), &f);
             });
             let handle = thread::spawn(move || {
                 if let Err(e) = handle.join() {
                     if let Some(e) = e.downcast_ref::<&'static str>() {
-                        eprintln!("Got an error: {}", e);
+                        eprintln!("Got an error: {e}");
                     } else {
-                        eprintln!("Got an unknown error: {:?}", e);
+                        eprintln!("Got an unknown error: {e:?}");
                     }
                     registry2.panicked.store(true, Ordering::SeqCst);
                     registry2.wait_condvar.notify_all();
@@ -314,19 +319,17 @@ impl WorkerRegistry {
         for handle in handles {
             handle.join().unwrap();
         }
-        if self.panicked.load(Ordering::SeqCst) {
-            panic!("tasks panicked");
-        }
+        assert!(!self.panicked.load(Ordering::SeqCst), "tasks panicked");
     }
 
-    /// Adds a task to this [WorkerRegistry].
+    /// Adds a task to this [`WorkerRegistry`].
     pub fn add_task(&self, task: CodeGenTask) {
         *self.task_count.lock() += 1;
         self.sender.send(Some(task)).unwrap();
     }
 
     /// Function executed by worker thread for generating IR for each function.
-    fn worker_thread<G: CodeGenerator>(&self, generator: &mut G, f: Arc<WithCall>) {
+    fn worker_thread<G: CodeGenerator>(&self, generator: &mut G, f: &Arc<WithCall>) {
         let context = Context::create();
         let mut builder = context.create_builder();
         let mut module = context.create_module(generator.get_name());
@@ -359,9 +362,7 @@ impl WorkerRegistry {
             *self.task_count.lock() -= 1;
             self.wait_condvar.notify_all();
         }
-        if !errors.is_empty() {
-            panic!("Codegen error: {}", errors.into_iter().sorted().join("\n----------\n"));
-        }
+        assert!(errors.is_empty(), "Codegen error: {}", errors.into_iter().sorted().join("\n----------\n"));
 
         let result = module.verify();
         if let Err(err) = result {
@@ -419,7 +420,7 @@ fn get_llvm_type<'ctx>(
     use TypeEnum::*;
     // we assume the type cache should already contain primitive types,
     // and they should be passed by value instead of passing as pointer.
-    type_cache.get(&unifier.get_representative(ty)).cloned().unwrap_or_else(|| {
+    type_cache.get(&unifier.get_representative(ty)).copied().unwrap_or_else(|| {
         let ty_enum = unifier.get_ty(ty);
         let result = match &*ty_enum {
             TObj { obj_id, fields, .. } => {
@@ -454,32 +455,31 @@ fn get_llvm_type<'ctx>(
                     &*definition.read()
                 {
                     let name = unifier.stringify(ty);
-                    match module.get_struct_type(&name) {
-                        Some(t) => t.ptr_type(AddressSpace::default()).into(),
-                        None => {
-                            let struct_type = ctx.opaque_struct_type(&name);
-                            type_cache.insert(
-                                unifier.get_representative(ty),
-                                struct_type.ptr_type(AddressSpace::default()).into()
-                            );
-                            let fields = fields_list
-                                .iter()
-                                .map(|f| {
-                                    get_llvm_type(
-                                        ctx,
-                                        module,
-                                        generator,
-                                        unifier,
-                                        top_level,
-                                        type_cache,
-                                        primitives,
-                                        fields[&f.0].0,
-                                    )
-                                })
-                                .collect_vec();
-                            struct_type.set_body(&fields, false);
+                    if let Some(t) = module.get_struct_type(&name) {
+                        t.ptr_type(AddressSpace::default()).into()
+                    } else {
+                        let struct_type = ctx.opaque_struct_type(&name);
+                        type_cache.insert(
+                            unifier.get_representative(ty),
                             struct_type.ptr_type(AddressSpace::default()).into()
-                        }
+                        );
+                        let fields = fields_list
+                            .iter()
+                            .map(|f| {
+                                get_llvm_type(
+                                    ctx,
+                                    module,
+                                    generator,
+                                    unifier,
+                                    top_level,
+                                    type_cache,
+                                    primitives,
+                                    fields[&f.0].0,
+                                )
+                            })
+                            .collect_vec();
+                        struct_type.set_body(&fields, false);
+                        struct_type.ptr_type(AddressSpace::default()).into()
                     }
                 } else {
                     unreachable!()
@@ -517,12 +517,12 @@ fn get_llvm_type<'ctx>(
     })
 }
 
-/// Retrieves the [LLVM type][BasicTypeEnum] corresponding to the [Type].
+/// Retrieves the [LLVM type][`BasicTypeEnum`] corresponding to the [`Type`].
 ///
 /// This function is used mainly to obtain the ABI representation of `ty`, e.g. a `bool` is
 /// would be represented by an `i1`.
 ///
-/// The difference between the in-memory representation (as returned by [get_llvm_type]) and the
+/// The difference between the in-memory representation (as returned by [`get_llvm_type`]) and the
 /// ABI representation is that the in-memory representation must be at least byte-sized and must
 /// be byte-aligned for the variable to be addressable in memory, whereas there is no such
 /// restriction for ABI representations.
@@ -551,7 +551,7 @@ fn get_llvm_abi_type<'ctx>(
 /// the target processor) by value, a synthetic parameter with a pointer type will be passed in the
 /// slot of the first parameter to act as the location of which the return value is passed into.
 ///
-/// See [https://releases.llvm.org/14.0.0/docs/LangRef.html#parameter-attributes] for more
+/// See <https://releases.llvm.org/14.0.0/docs/LangRef.html#parameter-attributes> for more
 /// information.
 fn need_sret(ty: BasicTypeEnum) -> bool {
     fn need_sret_impl(ty: BasicTypeEnum, maybe_large: bool) -> bool {
@@ -585,7 +585,7 @@ pub fn gen_func_impl<'ctx, G: CodeGenerator, F: FnOnce(&mut G, &mut CodeGenConte
     unifier.top_level = Some(top_level_ctx.clone());
 
     let mut cache = HashMap::new();
-    for (a, b) in task.subst.iter() {
+    for (a, b) in &task.subst {
         // this should be unification between variables and concrete types
         // and should not cause any problem...
         let b = task.store.to_unifier_type(&mut unifier, &primitives, *b, &mut cache);
@@ -599,7 +599,7 @@ pub fn gen_func_impl<'ctx, G: CodeGenerator, F: FnOnce(&mut G, &mut CodeGenConte
                     Err(err)
                 }
             })
-            .unwrap()
+            .unwrap();
     }
 
     // rebuild primitive store with unique representatives
@@ -642,22 +642,21 @@ pub fn gen_func_impl<'ctx, G: CodeGenerator, F: FnOnce(&mut G, &mut CodeGenConte
         (primitives.range, context.i32_type().array_type(3).ptr_type(AddressSpace::default()).into()),
         (primitives.exception, {
             let name = "Exception";
-            match module.get_struct_type(name) {
-                Some(t) => t.ptr_type(AddressSpace::default()).as_basic_type_enum(),
-                None => {
-                    let exception = context.opaque_struct_type("Exception");
-                    let int32 = context.i32_type().into();
-                    let int64 = context.i64_type().into();
-                    let str_ty = module.get_struct_type("str").unwrap().as_basic_type_enum();
-                    let fields = [int32, str_ty, int32, int32, str_ty, str_ty, int64, int64, int64];
-                    exception.set_body(&fields, false);
-                    exception.ptr_type(AddressSpace::default()).as_basic_type_enum()
-                }
+            if let Some(t) = module.get_struct_type(name) {
+                t.ptr_type(AddressSpace::default()).as_basic_type_enum()
+            } else {
+                let exception = context.opaque_struct_type("Exception");
+                let int32 = context.i32_type().into();
+                let int64 = context.i64_type().into();
+                let str_ty = module.get_struct_type("str").unwrap().as_basic_type_enum();
+                let fields = [int32, str_ty, int32, int32, str_ty, str_ty, int64, int64, int64];
+                exception.set_body(&fields, false);
+                exception.ptr_type(AddressSpace::default()).as_basic_type_enum()
             }
         })
     ]
     .iter()
-    .cloned()
+    .copied()
     .collect();
     // NOTE: special handling of option cannot use this type cache since it contains type var,
     // handled inside get_llvm_type instead
@@ -733,7 +732,7 @@ pub fn gen_func_impl<'ctx, G: CodeGenerator, F: FnOnce(&mut G, &mut CodeGenConte
     let body_bb = context.append_basic_block(fn_val, "body");
 
     let mut var_assignment = HashMap::new();
-    let offset = if has_sret { 1 } else { 0 };
+    let offset = u32::from(has_sret);
     for (n, arg) in args.iter().enumerate() {
         let param = fn_val.get_nth_param((n as u32) + offset).unwrap();
         let local_type = get_llvm_type(
@@ -779,7 +778,7 @@ pub fn gen_func_impl<'ctx, G: CodeGenerator, F: FnOnce(&mut G, &mut CodeGenConte
         let store = registry.static_value_store.lock();
         store.store[task.id].clone()
     };
-    for (k, v) in static_values.into_iter() {
+    for (k, v) in static_values {
         let (_, static_val, _) = var_assignment.get_mut(&args[k].name).unwrap();
         *static_val = Some(v);
     }
@@ -849,19 +848,19 @@ pub fn gen_func_impl<'ctx, G: CodeGenerator, F: FnOnce(&mut G, &mut CodeGenConte
         return_buffer,
         unwind_target: None,
         outer_catch_clauses: None,
-        const_strings: Default::default(),
+        const_strings: HashMap::default(),
         registry,
         var_assignment,
         type_cache,
         primitives,
         init_bb,
-        exception_val: Default::default(),
+        exception_val: Option::default(),
         builder,
         module,
         unifier,
         static_value_store,
         need_sret: has_sret,
-        current_loc: Default::default(),
+        current_loc: Location::default(),
         debug_info: (dibuilder, compile_unit, func_scope.as_debug_info_scope()),
     };
 
@@ -894,12 +893,12 @@ pub fn gen_func_impl<'ctx, G: CodeGenerator, F: FnOnce(&mut G, &mut CodeGenConte
 
 /// Generates LLVM IR for a function.
 ///
-/// * `context` - The [LLVM Context][Context] used in generating the function body.
-/// * `generator` - The [CodeGenerator] for generating various program constructs.
-/// * `registry` - The [WorkerRegistry] responsible for monitoring this function generation task.
-/// * `builder` - The [Builder] used for generating LLVM IR.
-/// * `module` - The [Module] of which the generated LLVM function will be inserted into.
-/// * `task` - The [CodeGenTask] associated with this function generation task.
+/// * `context` - The [LLVM Context][`Context`] used in generating the function body.
+/// * `generator` - The [`CodeGenerator`] for generating various program constructs.
+/// * `registry` - The [`WorkerRegistry`] responsible for monitoring this function generation task.
+/// * `builder` - The [`Builder`] used for generating LLVM IR.
+/// * `module` - The [`Module`] of which the generated LLVM function will be inserted into.
+/// * `task` - The [`CodeGenTask`] associated with this function generation task.
 ///
 pub fn gen_func<'ctx, G: CodeGenerator>(
     context: &'ctx Context,
@@ -917,15 +916,15 @@ pub fn gen_func<'ctx, G: CodeGenerator>(
 
 /// Converts the value of a boolean-like value `bool_value` into an `i1`.
 fn bool_to_i1<'ctx>(builder: &Builder<'ctx>, bool_value: IntValue<'ctx>) -> IntValue<'ctx> {
-    if bool_value.get_type().get_bit_width() != 1 {
+    if bool_value.get_type().get_bit_width() == 1 {
+        bool_value
+    } else {
         builder.build_int_compare(
             IntPredicate::NE,
             bool_value,
             bool_value.get_type().const_zero(),
             "tobool"
         )
-    } else {
-        bool_value
     }
 }
 
@@ -966,7 +965,7 @@ fn bool_to_i8<'ctx>(
 /// let cmp = lo < hi;
 /// ```
 ///
-/// Returns an `i1` [IntValue] representing the result of whether the `value` is in the range.
+/// Returns an `i1` [`IntValue`] representing the result of whether the `value` is in the range.
 fn gen_in_range_check<'ctx>(
     ctx: &CodeGenContext<'ctx, '_>,
     value: IntValue<'ctx>,
diff --git a/nac3core/src/codegen/stmt.rs b/nac3core/src/codegen/stmt.rs
index a0d6b19d6..8f76f416f 100644
--- a/nac3core/src/codegen/stmt.rs
+++ b/nac3core/src/codegen/stmt.rs
@@ -24,7 +24,7 @@ use nac3parser::ast::{
 };
 use std::convert::TryFrom;
 
-/// See [CodeGenerator::gen_var_alloc].
+/// See [`CodeGenerator::gen_var_alloc`].
 pub fn gen_var<'ctx>(
     ctx: &mut CodeGenContext<'ctx, '_>,
     ty: BasicTypeEnum<'ctx>,
@@ -54,7 +54,7 @@ pub fn gen_var<'ctx>(
     Ok(ptr)
 }
 
-/// See [CodeGenerator::gen_store_target].
+/// See [`CodeGenerator::gen_store_target`].
 pub fn gen_store_target<'ctx, G: CodeGenerator>(
     generator: &mut G,
     ctx: &mut CodeGenContext<'ctx, '_>,
@@ -84,9 +84,7 @@ pub fn gen_store_target<'ctx, G: CodeGenerator>(
             } else {
                 return Ok(None)
             };
-            let ptr = if let BasicValueEnum::PointerValue(v) = val {
-                v
-            } else {
+            let BasicValueEnum::PointerValue(ptr) = val else {
                 unreachable!();
             };
             unsafe {
@@ -164,7 +162,7 @@ pub fn gen_store_target<'ctx, G: CodeGenerator>(
     }))
 }
 
-/// See [CodeGenerator::gen_assign].
+/// See [`CodeGenerator::gen_assign`].
 pub fn gen_assign<'ctx, G: CodeGenerator>(
     generator: &mut G,
     ctx: &mut CodeGenContext<'ctx, '_>,
@@ -212,14 +210,14 @@ pub fn gen_assign<'ctx, G: CodeGenerator>(
                 let Some(src_ind) = handle_slice_indices(&None, &None, &None, ctx, generator, value)? else {
                     return Ok(())
                 };
-                list_slice_assignment(generator, ctx, ty, ls, (start, end, step), value, src_ind)
+                list_slice_assignment(generator, ctx, ty, ls, (start, end, step), value, src_ind);
             } else {
                 unreachable!()
             }
         }
         _ => {
             let name = if let ExprKind::Name { id, .. } = &target.node {
-                format!("{}.addr", id)
+                format!("{id}.addr")
             } else {
                 String::from("target.addr")
             };
@@ -241,7 +239,7 @@ pub fn gen_assign<'ctx, G: CodeGenerator>(
     Ok(())
 }
 
-/// See [CodeGenerator::gen_for].
+/// See [`CodeGenerator::gen_for`].
 pub fn gen_for<G: CodeGenerator>(
     generator: &mut G,
     ctx: &mut CodeGenContext<'_, '_>,
@@ -255,7 +253,7 @@ pub fn gen_for<G: CodeGenerator>(
         let int32 = ctx.ctx.i32_type();
         let size_t = generator.get_size_type(ctx.ctx);
         let zero = int32.const_zero();
-        let current = ctx.builder.get_insert_block().and_then(|bb| bb.get_parent()).unwrap();
+        let current = ctx.builder.get_insert_block().and_then(BasicBlock::get_parent).unwrap();
         let body_bb = ctx.ctx.append_basic_block(current, "for.body");
         let cont_bb = ctx.ctx.append_basic_block(current, "for.end");
         // if there is no orelse, we just go to cont_bb
@@ -368,7 +366,7 @@ pub fn gen_for<G: CodeGenerator>(
             generator.gen_block(ctx, body.iter())?;
         }
 
-        for (k, (_, _, counter)) in var_assignment.iter() {
+        for (k, (_, _, counter)) in &var_assignment {
             let (_, static_val, counter2) = ctx.var_assignment.get_mut(k).unwrap();
             if counter != counter2 {
                 *static_val = None;
@@ -387,7 +385,7 @@ pub fn gen_for<G: CodeGenerator>(
             }
         }
 
-        for (k, (_, _, counter)) in var_assignment.iter() {
+        for (k, (_, _, counter)) in &var_assignment {
             let (_, static_val, counter2) = ctx.var_assignment.get_mut(k).unwrap();
             if counter != counter2 {
                 *static_val = None;
@@ -402,7 +400,7 @@ pub fn gen_for<G: CodeGenerator>(
     Ok(())
 }
 
-/// See [CodeGenerator::gen_while].
+/// See [`CodeGenerator::gen_while`].
 pub fn gen_while<G: CodeGenerator>(
     generator: &mut G,
     ctx: &mut CodeGenContext<'_, '_>,
@@ -441,7 +439,7 @@ pub fn gen_while<G: CodeGenerator>(
         };
         ctx.builder.position_at_end(body_bb);
         generator.gen_block(ctx, body.iter())?;
-        for (k, (_, _, counter)) in var_assignment.iter() {
+        for (k, (_, _, counter)) in &var_assignment {
             let (_, static_val, counter2) = ctx.var_assignment.get_mut(k).unwrap();
             if counter != counter2 {
                 *static_val = None;
@@ -457,7 +455,7 @@ pub fn gen_while<G: CodeGenerator>(
                 ctx.builder.build_unconditional_branch(cont_bb);
             }
         }
-        for (k, (_, _, counter)) in var_assignment.iter() {
+        for (k, (_, _, counter)) in &var_assignment {
             let (_, static_val, counter2) = ctx.var_assignment.get_mut(k).unwrap();
             if counter != counter2 {
                 *static_val = None;
@@ -471,7 +469,7 @@ pub fn gen_while<G: CodeGenerator>(
     Ok(())
 }
 
-/// See [CodeGenerator::gen_if].
+/// See [`CodeGenerator::gen_if`].
 pub fn gen_if<G: CodeGenerator>(
     generator: &mut G,
     ctx: &mut CodeGenContext<'_, '_>,
@@ -503,7 +501,7 @@ pub fn gen_if<G: CodeGenerator>(
         };
         ctx.builder.position_at_end(body_bb);
         generator.gen_block(ctx, body.iter())?;
-        for (k, (_, _, counter)) in var_assignment.iter() {
+        for (k, (_, _, counter)) in &var_assignment {
             let (_, static_val, counter2) = ctx.var_assignment.get_mut(k).unwrap();
             if counter != counter2 {
                 *static_val = None;
@@ -529,7 +527,7 @@ pub fn gen_if<G: CodeGenerator>(
         if let Some(cont_bb) = cont_bb {
             ctx.builder.position_at_end(cont_bb);
         }
-        for (k, (_, _, counter)) in var_assignment.iter() {
+        for (k, (_, _, counter)) in &var_assignment {
             let (_, static_val, counter2) = ctx.var_assignment.get_mut(k).unwrap();
             if counter != counter2 {
                 *static_val = None;
@@ -571,8 +569,7 @@ pub fn get_builtins<'ctx>(
                 .ctx
                 .void_type()
                 .fn_type(&[ctx.get_llvm_type(generator, ctx.primitives.exception).into()], false),
-            "__nac3_resume" => ctx.ctx.void_type().fn_type(&[], false),
-            "__nac3_end_catch" => ctx.ctx.void_type().fn_type(&[], false),
+            "__nac3_resume" | "__nac3_end_catch" => ctx.ctx.void_type().fn_type(&[], false),
             _ => unimplemented!(),
         };
         let fun = ctx.module.add_function(symbol, ty, None);
@@ -613,20 +610,20 @@ pub fn exn_constructor<'ctx>(
         let id_ptr = ctx.builder.build_in_bounds_gep(zelf, &[zero, zero], "exn.id");
         let id = ctx.resolver.get_string_id(&exception_name);
         ctx.builder.build_store(id_ptr, int32.const_int(id as u64, false));
-        let empty_string = ctx.gen_const(generator, &Constant::Str("".into()), ctx.primitives.str);
+        let empty_string = ctx.gen_const(generator, &Constant::Str(String::new()), ctx.primitives.str);
         let ptr =
             ctx.builder.build_in_bounds_gep(zelf, &[zero, int32.const_int(5, false)], "exn.msg");
-        let msg = if !args.is_empty() {
-            args.remove(0).1.to_basic_value_enum(ctx, generator, ctx.primitives.str)?
-        } else {
+        let msg = if args.is_empty() {
             empty_string.unwrap()
+        } else {
+            args.remove(0).1.to_basic_value_enum(ctx, generator, ctx.primitives.str)?
         };
         ctx.builder.build_store(ptr, msg);
-        for i in [6, 7, 8].iter() {
-            let value = if !args.is_empty() {
-                args.remove(0).1.to_basic_value_enum(ctx, generator, ctx.primitives.int64)?
-            } else {
+        for i in &[6, 7, 8] {
+            let value = if args.is_empty() {
                 ctx.ctx.i64_type().const_zero().into()
+            } else {
+                args.remove(0).1.to_basic_value_enum(ctx, generator, ctx.primitives.int64)?
             };
             let ptr = ctx.builder.build_in_bounds_gep(
                 zelf,
@@ -636,7 +633,7 @@ pub fn exn_constructor<'ctx>(
             ctx.builder.build_store(ptr, value);
         }
         // set file, func to empty string
-        for i in [1, 4].iter() {
+        for i in &[1, 4] {
             let ptr = ctx.builder.build_in_bounds_gep(
                 zelf,
                 &[zero, int32.const_int(*i, false)],
@@ -645,7 +642,7 @@ pub fn exn_constructor<'ctx>(
             ctx.builder.build_store(ptr, empty_string.unwrap());
         }
         // set ints to zero
-        for i in [2, 3].iter() {
+        for i in &[2, 3] {
             let ptr = ctx.builder.build_in_bounds_gep(
                 zelf,
                 &[zero, int32.const_int(*i, false)],
@@ -768,7 +765,7 @@ pub fn gen_try<'ctx, 'a, G: CodeGenerator>(
 
         let mut clauses = Vec::new();
         let mut found_catch_all = false;
-        for handler_node in handlers.iter() {
+        for handler_node in handlers {
             let ExcepthandlerKind::ExceptHandler { type_, .. } = &handler_node.node;
             // none or Exception
             if type_.is_none()
@@ -779,30 +776,30 @@ pub fn gen_try<'ctx, 'a, G: CodeGenerator>(
                 clauses.push(None);
                 found_catch_all = true;
                 break;
-            } else {
-                let type_ = type_.as_ref().unwrap();
-                let exn_name = ctx.resolver.get_type_name(
-                    &ctx.top_level.definitions.read(),
-                    &mut ctx.unifier,
-                    type_.custom.unwrap(),
-                );
-                let obj_id = if let TypeEnum::TObj { obj_id, .. } = &*ctx.unifier.get_ty(type_.custom.unwrap()) {
-                    *obj_id
-                } else {
-                    unreachable!()
-                };
-                let exception_name = format!("{}:{}", ctx.resolver.get_exception_id(obj_id.0), exn_name);
-                let exn_id = ctx.resolver.get_string_id(&exception_name);
-                let exn_id_global =
-                    ctx.module.add_global(ctx.ctx.i32_type(), None, &format!("exn.{}", exn_id));
-                exn_id_global.set_initializer(&ctx.ctx.i32_type().const_int(exn_id as u64, false));
-                clauses.push(Some(exn_id_global.as_pointer_value().as_basic_value_enum()));
             }
+
+            let type_ = type_.as_ref().unwrap();
+            let exn_name = ctx.resolver.get_type_name(
+                &ctx.top_level.definitions.read(),
+                &mut ctx.unifier,
+                type_.custom.unwrap(),
+            );
+            let obj_id = if let TypeEnum::TObj { obj_id, .. } = &*ctx.unifier.get_ty(type_.custom.unwrap()) {
+                *obj_id
+            } else {
+                unreachable!()
+            };
+            let exception_name = format!("{}:{}", ctx.resolver.get_exception_id(obj_id.0), exn_name);
+            let exn_id = ctx.resolver.get_string_id(&exception_name);
+            let exn_id_global =
+                ctx.module.add_global(ctx.ctx.i32_type(), None, &format!("exn.{exn_id}"));
+            exn_id_global.set_initializer(&ctx.ctx.i32_type().const_int(exn_id as u64, false));
+            clauses.push(Some(exn_id_global.as_pointer_value().as_basic_value_enum()));
         }
         let mut all_clauses = clauses.clone();
         if let Some(old_clauses) = &ctx.outer_catch_clauses {
             if !found_catch_all {
-                all_clauses.extend_from_slice(&old_clauses.0)
+                all_clauses.extend_from_slice(&old_clauses.0);
             }
         }
         let old_clauses = ctx.outer_catch_clauses.replace((all_clauses, dispatcher, exn));
@@ -819,7 +816,9 @@ pub fn gen_try<'ctx, 'a, G: CodeGenerator>(
         ctx.return_target = old_return;
         ctx.loop_target = old_loop_target.or(ctx.loop_target).take();
 
-        let old_unwind = if !finalbody.is_empty() {
+        let old_unwind = if finalbody.is_empty() {
+            None
+        } else {
             let final_landingpad = ctx.ctx.append_basic_block(current_fun, "try.catch.final");
             ctx.builder.position_at_end(final_landingpad);
             ctx.builder.build_landing_pad(
@@ -832,8 +831,6 @@ pub fn gen_try<'ctx, 'a, G: CodeGenerator>(
             ctx.builder.build_unconditional_branch(cleanup.unwrap());
             ctx.builder.position_at_end(body);
             ctx.unwind_target.replace(final_landingpad)
-        } else {
-            None
         };
 
         // run end_catch before continue/break/return
@@ -886,7 +883,9 @@ pub fn gen_try<'ctx, 'a, G: CodeGenerator>(
 
         let mut post_handlers = Vec::new();
 
-        let exnid = if !handlers.is_empty() {
+        let exnid = if handlers.is_empty() {
+            None
+        } else {
             ctx.builder.position_at_end(dispatcher);
             unsafe {
                 let zero = ctx.ctx.i32_type().const_zero();
@@ -897,8 +896,6 @@ pub fn gen_try<'ctx, 'a, G: CodeGenerator>(
                 );
                 Some(ctx.builder.build_load(exnid_ptr, "exnid"))
             }
-        } else {
-            None
         };
 
         for (handler_node, exn_type) in handlers.iter().zip(clauses.iter()) {
@@ -1011,7 +1008,7 @@ pub fn gen_try<'ctx, 'a, G: CodeGenerator>(
                 let dest = ctx.builder.build_load(final_state, "final_dest");
                 ctx.builder.build_indirect_branch(dest, &final_targets);
             }
-            for block in final_paths.iter() {
+            for block in &final_paths {
                 if block.get_terminator().is_none() {
                     ctx.builder.position_at_end(*block);
                     ctx.builder.build_unconditional_branch(finalizer);
@@ -1034,7 +1031,7 @@ pub fn gen_try<'ctx, 'a, G: CodeGenerator>(
     }
 }
 
-/// See [CodeGenerator::gen_with].
+/// See [`CodeGenerator::gen_with`].
 pub fn gen_with<G: CodeGenerator>(
     _: &mut G,
     _: &mut CodeGenContext<'_, '_>,
@@ -1050,7 +1047,7 @@ pub fn gen_return<G: CodeGenerator>(
     ctx: &mut CodeGenContext<'_, '_>,
     value: &Option<Box<Expr<Option<Type>>>>,
 ) -> Result<(), String> {
-    let func = ctx.builder.get_insert_block().and_then(|bb| bb.get_parent()).unwrap();
+    let func = ctx.builder.get_insert_block().and_then(BasicBlock::get_parent).unwrap();
     let value = if let Some(v_expr) = value.as_ref() {
         if let Some(v) = generator.gen_expr(ctx, v_expr).transpose() {
             Some(
@@ -1096,7 +1093,7 @@ pub fn gen_return<G: CodeGenerator>(
     Ok(())
 }
 
-/// See [CodeGenerator::gen_stmt].
+/// See [`CodeGenerator::gen_stmt`].
 pub fn gen_stmt<G: CodeGenerator>(
     generator: &mut G,
     ctx: &mut CodeGenContext<'_, '_>,
@@ -1133,7 +1130,7 @@ pub fn gen_stmt<G: CodeGenerator>(
             let Some(value) = generator.gen_expr(ctx, value)? else {
                 return Ok(())
             };
-            for target in targets.iter() {
+            for target in targets {
                 generator.gen_assign(ctx, target, value.clone())?;
             }
         }
@@ -1185,7 +1182,7 @@ pub fn gen_stmt<G: CodeGenerator>(
                 err_msg,
                 [None, None, None],
                 stmt.location,
-            )
+            );
         }
         _ => unimplemented!()
     };
diff --git a/nac3core/src/symbol_resolver.rs b/nac3core/src/symbol_resolver.rs
index 02e3fa6c9..5224659d1 100644
--- a/nac3core/src/symbol_resolver.rs
+++ b/nac3core/src/symbol_resolver.rs
@@ -35,10 +35,10 @@ pub enum SymbolValue {
 }
 
 impl SymbolValue {
-    /// Creates a [SymbolValue] from a [Constant].
+    /// Creates a [`SymbolValue`] from a [`Constant`].
     ///
     /// * `constant` - The constant to create the value from.
-    /// * `expected_ty` - The expected type of the [SymbolValue].
+    /// * `expected_ty` - The expected type of the [`SymbolValue`].
     pub fn from_constant(
         constant: &Constant,
         expected_ty: Type,
@@ -50,21 +50,21 @@ impl SymbolValue {
                 if unifier.unioned(expected_ty, primitives.option) {
                     Ok(SymbolValue::OptionNone)
                 } else {
-                    Err(format!("Expected {:?}, but got Option", expected_ty))
+                    Err(format!("Expected {expected_ty:?}, but got Option"))
                 }
             }
             Constant::Bool(b) => {
                 if unifier.unioned(expected_ty, primitives.bool) {
                     Ok(SymbolValue::Bool(*b))
                 } else {
-                    Err(format!("Expected {:?}, but got bool", expected_ty))
+                    Err(format!("Expected {expected_ty:?}, but got bool"))
                 }
             }
             Constant::Str(s) => {
                 if unifier.unioned(expected_ty, primitives.str) {
                     Ok(SymbolValue::Str(s.to_string()))
                 } else {
-                    Err(format!("Expected {:?}, but got str", expected_ty))
+                    Err(format!("Expected {expected_ty:?}, but got str"))
                 }
             },
             Constant::Int(i) => {
@@ -107,14 +107,14 @@ impl SymbolValue {
                 if unifier.unioned(expected_ty, primitives.float) {
                     Ok(SymbolValue::Double(*f))
                 } else {
-                    Err(format!("Expected {:?}, but got float", expected_ty))
+                    Err(format!("Expected {expected_ty:?}, but got float"))
                 }
             },
-            _ => Err(format!("Unsupported value type {:?}", constant)),
+            _ => Err(format!("Unsupported value type {constant:?}")),
         }
     }
 
-    /// Returns the [Type] representing the data type of this value.
+    /// Returns the [`Type`] representing the data type of this value.
     pub fn get_type(&self, primitives: &PrimitiveStore, unifier: &mut Unifier) -> Type {
         match self {
             SymbolValue::I32(_) => primitives.int32,
@@ -133,12 +133,11 @@ impl SymbolValue {
                     ty: vs_tys,
                 })
             }
-            SymbolValue::OptionSome(_) => primitives.option,
-            SymbolValue::OptionNone => primitives.option,
+            SymbolValue::OptionSome(_) | SymbolValue::OptionNone => primitives.option,
         }
     }
 
-    /// Returns the [TypeAnnotation] representing the data type of this value.
+    /// Returns the [`TypeAnnotation`] representing the data type of this value.
     pub fn get_type_annotation(&self, primitives: &PrimitiveStore, unifier: &mut Unifier) -> TypeAnnotation {
         match self {
             SymbolValue::Bool(..) => TypeAnnotation::Primitive(primitives.bool),
@@ -157,7 +156,7 @@ impl SymbolValue {
             }
             SymbolValue::OptionNone => TypeAnnotation::CustomClass {
                 id: primitives.option.get_obj_id(unifier),
-                params: Default::default(),
+                params: Vec::default(),
             },
             SymbolValue::OptionSome(v) => {
                 let ty = v.get_type_annotation(primitives, unifier);
@@ -169,7 +168,7 @@ impl SymbolValue {
         }
     }
 
-    /// Returns the [TypeEnum] representing the data type of this value.
+    /// Returns the [`TypeEnum`] representing the data type of this value.
     pub fn get_type_enum(&self, primitives: &PrimitiveStore, unifier: &mut Unifier) -> Rc<TypeEnum> {
         let ty = self.get_type(primitives, unifier);
         unifier.get_ty(ty)
@@ -179,12 +178,12 @@ impl SymbolValue {
 impl Display for SymbolValue {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         match self {
-            SymbolValue::I32(i) => write!(f, "{}", i),
-            SymbolValue::I64(i) => write!(f, "int64({})", i),
-            SymbolValue::U32(i) => write!(f, "uint32({})", i),
-            SymbolValue::U64(i) => write!(f, "uint64({})", i),
-            SymbolValue::Str(s) => write!(f, "\"{}\"", s),
-            SymbolValue::Double(d) => write!(f, "{}", d),
+            SymbolValue::I32(i) => write!(f, "{i}"),
+            SymbolValue::I64(i) => write!(f, "int64({i})"),
+            SymbolValue::U32(i) => write!(f, "uint32({i})"),
+            SymbolValue::U64(i) => write!(f, "uint64({i})"),
+            SymbolValue::Str(s) => write!(f, "\"{s}\""),
+            SymbolValue::Double(d) => write!(f, "{d}"),
             SymbolValue::Bool(b) => {
                 if *b {
                     write!(f, "True")
@@ -193,9 +192,9 @@ impl Display for SymbolValue {
                 }
             }
             SymbolValue::Tuple(t) => {
-                write!(f, "({})", t.iter().map(|v| format!("{}", v)).collect::<Vec<_>>().join(", "))
+                write!(f, "({})", t.iter().map(|v| format!("{v}")).collect::<Vec<_>>().join(", "))
             }
-            SymbolValue::OptionSome(v) => write!(f, "Some({})", v),
+            SymbolValue::OptionSome(v) => write!(f, "Some({v})"),
             SymbolValue::OptionNone => write!(f, "none"),
         }
     }
@@ -212,7 +211,7 @@ pub trait StaticValue {
         generator: &mut dyn CodeGenerator,
     ) -> BasicValueEnum<'ctx>;
 
-    /// Converts this value to a LLVM [BasicValueEnum].
+    /// Converts this value to a LLVM [`BasicValueEnum`].
     fn to_basic_value_enum<'ctx>(
         &self,
         ctx: &mut CodeGenContext<'ctx, '_>,
@@ -272,7 +271,7 @@ impl<'ctx> From<StructValue<'ctx>> for ValueEnum<'ctx> {
 
 impl<'ctx> ValueEnum<'ctx> {
 
-    /// Converts this [ValueEnum] to a [BasicValueEnum].
+    /// Converts this [`ValueEnum`] to a [`BasicValueEnum`].
     pub fn to_basic_value_enum<'a>(
         self,
         ctx: &mut CodeGenContext<'ctx, 'a>,
@@ -376,39 +375,36 @@ pub fn parse_type_annotation<T>(
             Ok(primitives.exception)
         } else {
             let obj_id = resolver.get_identifier_def(*id);
-            match obj_id {
-                Ok(obj_id) => {
-                    let def = top_level_defs[obj_id.0].read();
-                    if let TopLevelDef::Class { fields, methods, type_vars, .. } = &*def {
-                        if !type_vars.is_empty() {
-                            return Err(format!(
-                                "Unexpected number of type parameters: expected {} but got 0",
-                                type_vars.len()
-                            ));
-                        }
-                        let fields = chain(
-                            fields.iter().map(|(k, v, m)| (*k, (*v, *m))),
-                            methods.iter().map(|(k, v, _)| (*k, (*v, false))),
-                        )
+            if let Ok(obj_id) = obj_id {
+                let def = top_level_defs[obj_id.0].read();
+                if let TopLevelDef::Class { fields, methods, type_vars, .. } = &*def {
+                    if !type_vars.is_empty() {
+                        return Err(format!(
+                            "Unexpected number of type parameters: expected {} but got 0",
+                            type_vars.len()
+                        ));
+                    }
+                    let fields = chain(
+                        fields.iter().map(|(k, v, m)| (*k, (*v, *m))),
+                        methods.iter().map(|(k, v, _)| (*k, (*v, false))),
+                    )
                         .collect();
-                        Ok(unifier.add_ty(TypeEnum::TObj {
-                            obj_id,
-                            fields,
-                            params: Default::default(),
-                        }))
-                    } else {
-                        Err(format!("Cannot use function name as type at {}", loc))
-                    }
+                    Ok(unifier.add_ty(TypeEnum::TObj {
+                        obj_id,
+                        fields,
+                        params: HashMap::default(),
+                    }))
+                } else {
+                    Err(format!("Cannot use function name as type at {loc}"))
                 }
-                Err(_) => {
-                    let ty = resolver
-                        .get_symbol_type(unifier, top_level_defs, primitives, *id)
-                        .map_err(|e| format!("Unknown type annotation at {}: {}", loc, e))?;
-                    if let TypeEnum::TVar { .. } = &*unifier.get_ty(ty) {
-                        Ok(ty)
-                    } else {
-                        Err(format!("Unknown type annotation {} at {}", id, loc))
-                    }
+            } else {
+                let ty = resolver
+                    .get_symbol_type(unifier, top_level_defs, primitives, *id)
+                    .map_err(|e| format!("Unknown type annotation at {loc}: {e}"))?;
+                if let TypeEnum::TVar { .. } = &*unifier.get_ty(ty) {
+                    Ok(ty)
+                } else {
+                    Err(format!("Unknown type annotation {id} at {loc}"))
                 }
             }
         }
@@ -520,7 +516,7 @@ impl dyn SymbolResolver + Send + Sync {
                     unreachable!("expected class definition")
                 }
             },
-            &mut |id| format!("typevar{}", id),
+            &mut |id| format!("typevar{id}"),
             &mut None,
         )
     }
diff --git a/nac3core/src/toplevel/builtins.rs b/nac3core/src/toplevel/builtins.rs
index 341ee132d..298f18978 100644
--- a/nac3core/src/toplevel/builtins.rs
+++ b/nac3core/src/toplevel/builtins.rs
@@ -49,7 +49,7 @@ pub fn get_exn_constructor(
         FuncArg {
             name: "msg".into(),
             ty: string,
-            default_value: Some(SymbolValue::Str("".into())),
+            default_value: Some(SymbolValue::Str(String::new())),
         },
         FuncArg { name: "param0".into(), ty: int64, default_value: Some(SymbolValue::I64(0)) },
         FuncArg { name: "param1".into(), ty: int64, default_value: Some(SymbolValue::I64(0)) },
@@ -58,20 +58,20 @@ pub fn get_exn_constructor(
     let exn_type = unifier.add_ty(TypeEnum::TObj {
         obj_id: DefinitionId(class_id),
         fields: exception_fields.iter().map(|(a, b, c)| (*a, (*b, *c))).collect(),
-        params: Default::default(),
+        params: HashMap::default(),
     });
     let signature = unifier.add_ty(TypeEnum::TFunc(FunSignature {
         args: exn_cons_args,
         ret: exn_type,
-        vars: Default::default(),
+        vars: HashMap::default(),
     }));
     let fun_def = TopLevelDef::Function {
-        name: format!("{}.__init__", name),
+        name: format!("{name}.__init__"),
         simple_name: "__init__".into(),
         signature,
-        var_id: Default::default(),
-        instance_to_symbol: Default::default(),
-        instance_to_stmt: Default::default(),
+        var_id: Vec::default(),
+        instance_to_symbol: HashMap::default(),
+        instance_to_stmt: HashMap::default(),
         resolver: None,
         codegen_callback: Some(Arc::new(GenCall::new(Box::new(exn_constructor)))),
         loc: None,
@@ -79,12 +79,12 @@ pub fn get_exn_constructor(
     let class_def = TopLevelDef::Class {
         name: name.into(),
         object_id: DefinitionId(class_id),
-        type_vars: Default::default(),
+        type_vars: Vec::default(),
         fields: exception_fields,
         methods: vec![("__init__".into(), signature, DefinitionId(cons_id))],
         ancestors: vec![
-            TypeAnnotation::CustomClass { id: DefinitionId(class_id), params: Default::default() },
-            TypeAnnotation::CustomClass { id: DefinitionId(7), params: Default::default() },
+            TypeAnnotation::CustomClass { id: DefinitionId(class_id), params: Vec::default() },
+            TypeAnnotation::CustomClass { id: DefinitionId(7), params: Vec::default() },
         ],
         constructor: Some(signature),
         resolver: None,
@@ -93,7 +93,7 @@ pub fn get_exn_constructor(
     (fun_def, class_def, signature, exn_type)
 }
 
-/// Creates a NumPy [TopLevelDef] function by code generation.
+/// Creates a NumPy [`TopLevelDef`] function by code generation.
 ///
 /// * `name`: The name of the implemented NumPy function.
 /// * `ret_ty`: The return type of this function.
@@ -120,16 +120,16 @@ fn create_fn_by_codegen(
             ret: ret_ty,
             vars: var_map.clone(),
         })),
-        var_id: Default::default(),
-        instance_to_symbol: Default::default(),
-        instance_to_stmt: Default::default(),
+        var_id: Vec::default(),
+        instance_to_symbol: HashMap::default(),
+        instance_to_stmt: HashMap::default(),
         resolver: None,
         codegen_callback: Some(Arc::new(GenCall::new(codegen_callback))),
         loc: None,
     }))
 }
 
-/// Creates a NumPy [TopLevelDef] function using an LLVM intrinsic.
+/// Creates a NumPy [`TopLevelDef`] function using an LLVM intrinsic.
 ///
 /// * `name`: The name of the implemented NumPy function.
 /// * `ret_ty`: The return type of this function.
@@ -191,7 +191,7 @@ fn create_fn_by_intrinsic(
     )
 }
 
-/// Creates a unary NumPy [TopLevelDef] function using an extern function (e.g. from `libc` or
+/// Creates a unary NumPy [`TopLevelDef`] function using an extern function (e.g. from `libc` or
 /// `libm`).
 ///
 /// * `name`: The name of the implemented NumPy function.
@@ -363,9 +363,9 @@ pub fn get_builtins(primitives: &mut (PrimitiveStore, Unifier)) -> BuiltinInfo {
         Arc::new(RwLock::new(TopLevelDef::Class {
             name: "Exception".into(),
             object_id: DefinitionId(7),
-            type_vars: Default::default(),
+            type_vars: Vec::default(),
             fields: exception_fields,
-            methods: Default::default(),
+            methods: Vec::default(),
             ancestors: vec![],
             constructor: None,
             resolver: None,
@@ -398,7 +398,7 @@ pub fn get_builtins(primitives: &mut (PrimitiveStore, Unifier)) -> BuiltinInfo {
                 ],
                 ancestors: vec![TypeAnnotation::CustomClass {
                     id: DefinitionId(10),
-                    params: Default::default(),
+                    params: Vec::default(),
                 }],
                 constructor: None,
                 resolver: None,
@@ -410,8 +410,8 @@ pub fn get_builtins(primitives: &mut (PrimitiveStore, Unifier)) -> BuiltinInfo {
             simple_name: "is_some".into(),
             signature: is_some_ty.0,
             var_id: vec![option_ty_var_id],
-            instance_to_symbol: Default::default(),
-            instance_to_stmt: Default::default(),
+            instance_to_symbol: HashMap::default(),
+            instance_to_stmt: HashMap::default(),
             resolver: None,
             codegen_callback: Some(Arc::new(GenCall::new(Box::new(
                 |ctx, obj, _, _, generator| {
@@ -435,8 +435,8 @@ pub fn get_builtins(primitives: &mut (PrimitiveStore, Unifier)) -> BuiltinInfo {
             simple_name: "is_none".into(),
             signature: is_some_ty.0,
             var_id: vec![option_ty_var_id],
-            instance_to_symbol: Default::default(),
-            instance_to_stmt: Default::default(),
+            instance_to_symbol: HashMap::default(),
+            instance_to_stmt: HashMap::default(),
             resolver: None,
             codegen_callback: Some(Arc::new(GenCall::new(Box::new(
                 |ctx, obj, _, _, generator| {
@@ -460,8 +460,8 @@ pub fn get_builtins(primitives: &mut (PrimitiveStore, Unifier)) -> BuiltinInfo {
             simple_name: "unwrap".into(),
             signature: unwrap_ty.0,
             var_id: vec![option_ty_var_id],
-            instance_to_symbol: Default::default(),
-            instance_to_stmt: Default::default(),
+            instance_to_symbol: HashMap::default(),
+            instance_to_stmt: HashMap::default(),
             resolver: None,
             codegen_callback: Some(Arc::new(GenCall::new(Box::new(
                 |_, _, _, _, _| {
@@ -478,9 +478,9 @@ pub fn get_builtins(primitives: &mut (PrimitiveStore, Unifier)) -> BuiltinInfo {
                 ret: int32,
                 vars: var_map.clone(),
             })),
-            var_id: Default::default(),
-            instance_to_symbol: Default::default(),
-            instance_to_stmt: Default::default(),
+            var_id: Vec::default(),
+            instance_to_symbol: HashMap::default(),
+            instance_to_stmt: HashMap::default(),
             resolver: None,
             codegen_callback: Some(Arc::new(GenCall::new(Box::new(
                 |ctx, _, fun, args, generator| {
@@ -553,9 +553,9 @@ pub fn get_builtins(primitives: &mut (PrimitiveStore, Unifier)) -> BuiltinInfo {
                 ret: int64,
                 vars: var_map.clone(),
             })),
-            var_id: Default::default(),
-            instance_to_symbol: Default::default(),
-            instance_to_stmt: Default::default(),
+            var_id: Vec::default(),
+            instance_to_symbol: HashMap::default(),
+            instance_to_stmt: HashMap::default(),
             resolver: None,
             codegen_callback: Some(Arc::new(GenCall::new(Box::new(
                 |ctx, _, fun, args, generator| {
@@ -624,9 +624,9 @@ pub fn get_builtins(primitives: &mut (PrimitiveStore, Unifier)) -> BuiltinInfo {
                 ret: uint32,
                 vars: var_map.clone(),
             })),
-            var_id: Default::default(),
-            instance_to_symbol: Default::default(),
-            instance_to_stmt: Default::default(),
+            var_id: Vec::default(),
+            instance_to_symbol: HashMap::default(),
+            instance_to_stmt: HashMap::default(),
             resolver: None,
             codegen_callback: Some(Arc::new(GenCall::new(Box::new(
                 |ctx, _, fun, args, generator| {
@@ -701,9 +701,9 @@ pub fn get_builtins(primitives: &mut (PrimitiveStore, Unifier)) -> BuiltinInfo {
                 ret: uint64,
                 vars: var_map.clone(),
             })),
-            var_id: Default::default(),
-            instance_to_symbol: Default::default(),
-            instance_to_stmt: Default::default(),
+            var_id: Vec::default(),
+            instance_to_symbol: HashMap::default(),
+            instance_to_stmt: HashMap::default(),
             resolver: None,
             codegen_callback: Some(Arc::new(GenCall::new(Box::new(
                 |ctx, _, fun, args, generator| {
@@ -777,9 +777,9 @@ pub fn get_builtins(primitives: &mut (PrimitiveStore, Unifier)) -> BuiltinInfo {
                 ret: float,
                 vars: var_map.clone(),
             })),
-            var_id: Default::default(),
-            instance_to_symbol: Default::default(),
-            instance_to_stmt: Default::default(),
+            var_id: Vec::default(),
+            instance_to_symbol: HashMap::default(),
+            instance_to_stmt: HashMap::default(),
             resolver: None,
             codegen_callback: Some(Arc::new(GenCall::new(Box::new(
                 |ctx, _, fun, args, generator| {
@@ -927,11 +927,11 @@ pub fn get_builtins(primitives: &mut (PrimitiveStore, Unifier)) -> BuiltinInfo {
                     },
                 ],
                 ret: range,
-                vars: Default::default(),
+                vars: HashMap::default(),
             })),
-            var_id: Default::default(),
-            instance_to_symbol: Default::default(),
-            instance_to_stmt: Default::default(),
+            var_id: Vec::default(),
+            instance_to_symbol: HashMap::default(),
+            instance_to_stmt: HashMap::default(),
             resolver: None,
             codegen_callback: Some(Arc::new(GenCall::new(Box::new(
                 |ctx, _, _, args, generator| {
@@ -1013,11 +1013,11 @@ pub fn get_builtins(primitives: &mut (PrimitiveStore, Unifier)) -> BuiltinInfo {
             signature: primitives.1.add_ty(TypeEnum::TFunc(FunSignature {
                 args: vec![FuncArg { name: "s".into(), ty: string, default_value: None }],
                 ret: string,
-                vars: Default::default(),
+                vars: HashMap::default(),
             })),
-            var_id: Default::default(),
-            instance_to_symbol: Default::default(),
-            instance_to_stmt: Default::default(),
+            var_id: Vec::default(),
+            instance_to_symbol: HashMap::default(),
+            instance_to_stmt: HashMap::default(),
             resolver: None,
             codegen_callback: Some(Arc::new(GenCall::new(Box::new(
                 |ctx, _, fun, args, generator| {
@@ -1035,9 +1035,9 @@ pub fn get_builtins(primitives: &mut (PrimitiveStore, Unifier)) -> BuiltinInfo {
                 ret: primitives.0.bool,
                 vars: var_map.clone(),
             })),
-            var_id: Default::default(),
-            instance_to_symbol: Default::default(),
-            instance_to_stmt: Default::default(),
+            var_id: Vec::default(),
+            instance_to_symbol: HashMap::default(),
+            instance_to_stmt: HashMap::default(),
             resolver: None,
             codegen_callback: Some(Arc::new(GenCall::new(Box::new(
                 |ctx, _, fun, args, generator| {
@@ -1283,8 +1283,8 @@ pub fn get_builtins(primitives: &mut (PrimitiveStore, Unifier)) -> BuiltinInfo {
                         .collect(),
                 })),
                 var_id: vec![arg_ty.1],
-                instance_to_symbol: Default::default(),
-                instance_to_stmt: Default::default(),
+                instance_to_symbol: HashMap::default(),
+                instance_to_stmt: HashMap::default(),
                 resolver: None,
                 codegen_callback: Some(Arc::new(GenCall::new(Box::new(
                     |ctx, _, fun, args, generator| {
@@ -1305,10 +1305,10 @@ pub fn get_builtins(primitives: &mut (PrimitiveStore, Unifier)) -> BuiltinInfo {
                                     None,
                                 )
                                 .into_int_value();
-                            if len.get_type().get_bit_width() != 32 {
-                                Some(ctx.builder.build_int_truncate(len, int32, "len2i32").into())
-                            } else {
+                            if len.get_type().get_bit_width() == 32 {
                                 Some(len.into())
+                            } else {
+                                Some(ctx.builder.build_int_truncate(len, int32, "len2i32").into())
                             }
                         })
                     },
@@ -1327,9 +1327,9 @@ pub fn get_builtins(primitives: &mut (PrimitiveStore, Unifier)) -> BuiltinInfo {
                 ret: num_ty.0,
                 vars: var_map.clone(),
             })),
-            var_id: Default::default(),
-            instance_to_symbol: Default::default(),
-            instance_to_stmt: Default::default(),
+            var_id: Vec::default(),
+            instance_to_symbol: HashMap::default(),
+            instance_to_stmt: HashMap::default(),
             resolver: None,
             codegen_callback: Some(Arc::new(GenCall::new(Box::new(
                 |ctx, _, fun, args, generator| {
@@ -1389,9 +1389,9 @@ pub fn get_builtins(primitives: &mut (PrimitiveStore, Unifier)) -> BuiltinInfo {
                 ret: num_ty.0,
                 vars: var_map.clone(),
             })),
-            var_id: Default::default(),
-            instance_to_symbol: Default::default(),
-            instance_to_stmt: Default::default(),
+            var_id: Vec::default(),
+            instance_to_symbol: HashMap::default(),
+            instance_to_stmt: HashMap::default(),
             resolver: None,
             codegen_callback: Some(Arc::new(GenCall::new(Box::new(
                 |ctx, _, fun, args, generator| {
@@ -1448,9 +1448,9 @@ pub fn get_builtins(primitives: &mut (PrimitiveStore, Unifier)) -> BuiltinInfo {
                 ret: num_ty.0,
                 vars: var_map.clone(),
             })),
-            var_id: Default::default(),
-            instance_to_symbol: Default::default(),
-            instance_to_stmt: Default::default(),
+            var_id: Vec::default(),
+            instance_to_symbol: HashMap::default(),
+            instance_to_stmt: HashMap::default(),
             resolver: None,
             codegen_callback: Some(Arc::new(GenCall::new(Box::new(
                 |ctx, _, fun, args, generator| {
@@ -1888,8 +1888,8 @@ pub fn get_builtins(primitives: &mut (PrimitiveStore, Unifier)) -> BuiltinInfo {
                 vars: HashMap::from([(option_ty_var_id, option_ty_var)]),
             })),
             var_id: vec![option_ty_var_id],
-            instance_to_symbol: Default::default(),
-            instance_to_stmt: Default::default(),
+            instance_to_symbol: HashMap::default(),
+            instance_to_stmt: HashMap::default(),
             resolver: None,
             codegen_callback: Some(Arc::new(GenCall::new(Box::new(
                 |ctx, _, fun, args, generator| {
diff --git a/nac3core/src/toplevel/composer.rs b/nac3core/src/toplevel/composer.rs
index f5d264449..d47be350c 100644
--- a/nac3core/src/toplevel/composer.rs
+++ b/nac3core/src/toplevel/composer.rs
@@ -41,13 +41,14 @@ pub struct TopLevelComposer {
 
 impl Default for TopLevelComposer {
     fn default() -> Self {
-        Self::new(vec![], Default::default()).0
+        Self::new(vec![], ComposerConfig::default()).0
     }
 }
 
 impl TopLevelComposer {
     /// return a composer and things to make a "primitive" symbol resolver, so that the symbol
     /// resolver can later figure out primitive type definitions when passed a primitive type name
+    #[must_use]
     pub fn new(
         builtins: Vec<(StrRef, FunSignature, Arc<GenCall>)>,
         core_config: ComposerConfig,
@@ -77,11 +78,11 @@ impl TopLevelComposer {
             "Some".into(),
             "Option".into(),
         ]);
-        let defined_names: HashSet<String> = Default::default();
-        let method_class: HashMap<DefinitionId, DefinitionId> = Default::default();
+        let defined_names = HashSet::default();
+        let method_class = HashMap::default();
 
-        let mut builtin_id: HashMap<StrRef, DefinitionId> = Default::default();
-        let mut builtin_ty: HashMap<StrRef, Type> = Default::default();
+        let mut builtin_id = HashMap::default();
+        let mut builtin_ty = HashMap::default();
 
         let builtin_name_list = definition_ast_list.iter()
             .map(|def_ast| match *def_ast.0.read() {
@@ -123,9 +124,9 @@ impl TopLevelComposer {
                     name: name.into(),
                     simple_name: name,
                     signature: fun_sig,
-                    instance_to_stmt: Default::default(),
-                    instance_to_symbol: Default::default(),
-                    var_id: Default::default(),
+                    instance_to_stmt: HashMap::default(),
+                    instance_to_symbol: HashMap::default(),
+                    var_id: Vec::default(),
                     resolver: None,
                     codegen_callback: Some(codegen_callback),
                     loc: None,
@@ -151,6 +152,7 @@ impl TopLevelComposer {
         )
     }
 
+    #[must_use]
     pub fn make_top_level_context(&self) -> TopLevelContext {
         TopLevelContext {
             definitions: RwLock::new(
@@ -166,6 +168,7 @@ impl TopLevelComposer {
         }
     }
 
+    #[must_use]
     pub fn extract_def_list(&self) -> Vec<Arc<RwLock<TopLevelDef>>> {
         self.definition_ast_list.iter().map(|(def, ..)| def.clone()).collect_vec()
     }
@@ -176,9 +179,19 @@ impl TopLevelComposer {
         &mut self,
         ast: Stmt<()>,
         resolver: Option<Arc<dyn SymbolResolver + Send + Sync>>,
-        mod_path: String,
+        mod_path: &str,
         allow_no_constructor: bool,
     ) -> Result<(StrRef, DefinitionId, Option<Type>), String> {
+        type MethodInfo = (
+            // the simple method name without class name
+            StrRef,
+            // in this top level def, method name is prefixed with the class name
+            Arc<RwLock<TopLevelDef>>,
+            DefinitionId,
+            Type,
+            Stmt<()>,
+        );
+
         let defined_names = &mut self.defined_names;
         match &ast.node {
             ast::StmtKind::ClassDef { name: class_name, bases, body, .. } => {
@@ -222,15 +235,6 @@ impl TopLevelComposer {
                 // parse class def body and register class methods into the def list.
                 // module's symbol resolver would not know the name of the class methods,
                 // thus cannot return their definition_id
-                type MethodInfo = (
-                    // the simple method name without class name
-                    StrRef,
-                    // in this top level def, method name is prefixed with the class name
-                    Arc<RwLock<TopLevelDef>>,
-                    DefinitionId,
-                    Type,
-                    Stmt<()>,
-                );
                 let mut class_method_name_def_ids: Vec<MethodInfo> = Vec::new();
                 // we do not push anything to the def list, so we keep track of the index
                 // and then push in the correct order after the for loop
@@ -288,9 +292,6 @@ impl TopLevelComposer {
                             dummy_method_type,
                             b.clone(),
                         ));
-                    } else {
-                        // do nothing
-                        continue;
                     }
                 }
 
@@ -299,7 +300,7 @@ impl TopLevelComposer {
                 // get the methods into the top level class_def
                 for (name, _, id, ty, ..) in &class_method_name_def_ids {
                     let mut class_def = class_def_ast.0.write();
-                    if let TopLevelDef::Class { methods, .. } = class_def.deref_mut() {
+                    if let TopLevelDef::Class { methods, .. } = &mut *class_def {
                         methods.push((*name, *ty, *id));
                         self.method_class.insert(*id, DefinitionId(class_def_id));
                     } else {
@@ -320,7 +321,7 @@ impl TopLevelComposer {
                 let global_fun_name = if mod_path.is_empty() {
                     name.to_string()
                 } else {
-                    format!("{}.{}", mod_path, name)
+                    format!("{mod_path}.{name}")
                 };
                 if !defined_names.insert(global_fun_name.clone()) {
                     return Err(format!(
@@ -383,7 +384,7 @@ impl TopLevelComposer {
             // only deal with class def here
             let mut class_def = class_def.write();
             let (class_bases_ast, class_def_type_vars, class_resolver) = {
-                if let TopLevelDef::Class { type_vars, resolver, .. } = class_def.deref_mut() {
+                if let TopLevelDef::Class { type_vars, resolver, .. } = &mut *class_def {
                     if let Some(ast::Located {
                         node: ast::StmtKind::ClassDef { bases, .. }, ..
                     }) = class_ast
@@ -397,7 +398,7 @@ impl TopLevelComposer {
                 }
             };
             let class_resolver = class_resolver.as_ref().unwrap();
-            let class_resolver = class_resolver.deref();
+            let class_resolver = &**class_resolver;
 
             let mut is_generic = false;
             for b in class_bases_ast {
@@ -415,14 +416,13 @@ impl TopLevelComposer {
                             )
                         } =>
                     {
-                        if !is_generic {
-                            is_generic = true;
-                        } else {
+                        if is_generic {
                             return Err(format!(
                                 "only single Generic[...] is allowed (at {})",
                                 b.location
                             ));
                         }
+                        is_generic = true;
 
                         let type_var_list: Vec<&ast::Expr<()>>;
                         // if `class A(Generic[T, V, G])`
@@ -430,7 +430,7 @@ impl TopLevelComposer {
                             type_var_list = elts.iter().collect_vec();
                         // `class A(Generic[T])`
                         } else {
-                            type_var_list = vec![slice.deref()];
+                            type_var_list = vec![&**slice];
                         }
 
                         // parse the type vars
@@ -509,7 +509,7 @@ impl TopLevelComposer {
                 let (class_def_id, class_bases, class_ancestors, class_resolver, class_type_vars) = {
                     if let TopLevelDef::Class {
                         ancestors, resolver, object_id, type_vars, ..
-                    } = class_def.deref_mut()
+                    } = &mut *class_def
                     {
                         if let Some(ast::Located {
                             node: ast::StmtKind::ClassDef { bases, .. },
@@ -525,7 +525,7 @@ impl TopLevelComposer {
                     }
                 };
                 let class_resolver = class_resolver.as_ref().unwrap();
-                let class_resolver = class_resolver.deref();
+                let class_resolver = &**class_resolver;
 
                 let mut has_base = false;
                 for b in class_bases {
@@ -589,11 +589,11 @@ impl TopLevelComposer {
         }
 
         // second, get all ancestors
-        let mut ancestors_store: HashMap<DefinitionId, Vec<TypeAnnotation>> = Default::default();
+        let mut ancestors_store: HashMap<DefinitionId, Vec<TypeAnnotation>> = HashMap::default();
         let mut get_all_ancestors = |class_def: &Arc<RwLock<TopLevelDef>>| {
             let class_def = class_def.read();
             let (class_ancestors, class_id) = {
-                if let TopLevelDef::Class { ancestors, object_id, .. } = class_def.deref() {
+                if let TopLevelDef::Class { ancestors, object_id, .. } = &*class_def {
                     (ancestors, *object_id)
                 } else {
                     return Ok(());
@@ -630,7 +630,7 @@ impl TopLevelComposer {
             let mut class_def = class_def.write();
             let (class_ancestors, class_id, class_type_vars) = {
                 if let TopLevelDef::Class { ancestors, object_id, type_vars, .. } =
-                    class_def.deref_mut()
+                    &mut *class_def
                 {
                     (ancestors, *object_id, type_vars)
                 } else {
@@ -652,7 +652,7 @@ impl TopLevelComposer {
             {
                 // if inherited from Exception, the body should be a pass
                 if let ast::StmtKind::ClassDef { body, .. } = &class_ast.as_ref().unwrap().node {
-                    for stmt in body.iter() {
+                    for stmt in body {
                         if matches!(
                             stmt.node,
                             ast::StmtKind::FunctionDef { .. } | ast::StmtKind::AnnAssign { .. }
@@ -695,7 +695,7 @@ impl TopLevelComposer {
             }
             if matches!(&*class_def.read(), TopLevelDef::Class { .. }) {
                 if let Err(e) = Self::analyze_single_class_methods_fields(
-                    class_def.clone(),
+                    class_def,
                     &class_ast.as_ref().unwrap().node,
                     &temp_def_list,
                     unifier,
@@ -724,13 +724,13 @@ impl TopLevelComposer {
                     continue;
                 }
                 let mut class_def = class_def.write();
-                if let TopLevelDef::Class { ancestors, .. } = class_def.deref() {
+                if let TopLevelDef::Class { ancestors, .. } = &*class_def {
                     // if the length of the ancestor is equal to the current depth
                     // it means that all the ancestors of the class is handled
                     if ancestors.len() == current_ancestor_depth {
                         finished = false;
                         Self::analyze_single_class_ancestors(
-                            class_def.deref_mut(),
+                            &mut class_def,
                             &temp_def_list,
                             unifier,
                             primitives,
@@ -742,10 +742,9 @@ impl TopLevelComposer {
 
             if finished {
                 break;
-            } else {
-                current_ancestor_depth += 1;
             }
 
+            current_ancestor_depth += 1;
             if current_ancestor_depth > def_ast_list.len() + 1 {
                 unreachable!("cannot be longer than the whole top level def list")
             }
@@ -764,11 +763,11 @@ impl TopLevelComposer {
                 errors.insert(e);
             }
         }
-        for ty in subst_list.unwrap().into_iter() {
+        for ty in subst_list.unwrap() {
             if let TypeEnum::TObj { obj_id, params, fields } = &*unifier.get_ty(ty) {
                 let mut new_fields = HashMap::new();
                 let mut need_subst = false;
-                for (name, (ty, mutable)) in fields.iter() {
+                for (name, (ty, mutable)) in fields {
                     let substituted = unifier.subst(*ty, params);
                     need_subst |= substituted.is_some();
                     new_fields.insert(*name, (substituted.unwrap_or(*ty), *mutable));
@@ -817,10 +816,8 @@ impl TopLevelComposer {
         let mut errors = HashSet::new();
         let mut analyze = |function_def: &Arc<RwLock<TopLevelDef>>, function_ast: &Option<Stmt>| {
             let mut function_def = function_def.write();
-            let function_def = function_def.deref_mut();
-            let function_ast = if let Some(x) = function_ast.as_ref() {
-                x
-            } else {
+            let function_def = &mut *function_def;
+            let Some(function_ast) = function_ast.as_ref() else {
                 // if let TopLevelDef::Function { name, .. } = ``
                 return Ok(());
             };
@@ -835,13 +832,13 @@ impl TopLevelComposer {
                 if let ast::StmtKind::FunctionDef { args, returns, .. } = &function_ast.node {
                     let resolver = resolver.as_ref();
                     let resolver = resolver.unwrap();
-                    let resolver = resolver.deref();
+                    let resolver = &**resolver;
 
                     let mut function_var_map: HashMap<u32, Type> = HashMap::new();
                     let arg_types = {
                         // make sure no duplicate parameter
                         let mut defined_parameter_name: HashSet<_> = HashSet::new();
-                        for x in args.args.iter() {
+                        for x in &args.args {
                             if !defined_parameter_name.insert(x.node.arg)
                                 || keyword_list.contains(&x.node.arg)
                             {
@@ -1037,7 +1034,7 @@ impl TopLevelComposer {
     }
 
     fn analyze_single_class_methods_fields(
-        class_def: Arc<RwLock<TopLevelDef>>,
+        class_def: &Arc<RwLock<TopLevelDef>>,
         class_ast: &ast::StmtKind<()>,
         temp_def_list: &[Arc<RwLock<TopLevelDef>>],
         unifier: &mut Unifier,
@@ -1091,7 +1088,7 @@ impl TopLevelComposer {
                         // check method parameters cannot have same name
                         let mut defined_parameter_name: HashSet<_> = HashSet::new();
                         let zelf: StrRef = "self".into();
-                        for x in args.args.iter() {
+                        for x in &args.args {
                             if !defined_parameter_name.insert(x.node.arg)
                                 || (keyword_list.contains(&x.node.arg) && x.node.arg != zelf)
                             {
@@ -1206,7 +1203,7 @@ impl TopLevelComposer {
                                 // into the list for later unification
                                 type_var_to_concrete_def
                                     .insert(dummy_func_arg.ty, type_ann.clone());
-                                result.push(dummy_func_arg)
+                                result.push(dummy_func_arg);
                             }
                         }
                         result
@@ -1255,7 +1252,7 @@ impl TopLevelComposer {
                     };
 
                     if let TopLevelDef::Function { var_id, .. } =
-                        temp_def_list.get(method_id.0).unwrap().write().deref_mut()
+                        &mut *temp_def_list.get(method_id.0).unwrap().write()
                     {
                         var_id.extend_from_slice(method_var_map
                             .iter()
@@ -1410,7 +1407,7 @@ impl TopLevelComposer {
                     // find if there is a method with same name in the child class
                     let mut to_be_added = (*anc_method_name, *anc_method_ty, *anc_method_def_id);
                     for (class_method_name, class_method_ty, class_method_defid) in
-                        class_methods_def.iter()
+                        &*class_methods_def
                     {
                         if class_method_name == anc_method_name {
                             // ignore and handle self
@@ -1424,8 +1421,7 @@ impl TopLevelComposer {
                                 );
                             if !ok {
                                 return Err(format!(
-                                    "method {} has same name as ancestors' method, but incompatible type",
-                                    class_method_name
+                                    "method {class_method_name} has same name as ancestors' method, but incompatible type"
                                 ));
                             }
                             // mark it as added
@@ -1439,7 +1435,7 @@ impl TopLevelComposer {
                 }
                 // add those that are not overriding method to the new_child_methods
                 for (class_method_name, class_method_ty, class_method_defid) in
-                    class_methods_def.iter()
+                    &*class_methods_def
                 {
                     if !is_override.contains(class_method_name) {
                         new_child_methods.push((
@@ -1459,17 +1455,16 @@ impl TopLevelComposer {
                 for (anc_field_name, anc_field_ty, mutable) in fields {
                     let to_be_added = (*anc_field_name, *anc_field_ty, *mutable);
                     // find if there is a fields with the same name in the child class
-                    for (class_field_name, ..) in class_fields_def.iter() {
+                    for (class_field_name, ..) in &*class_fields_def {
                         if class_field_name == anc_field_name {
                             return Err(format!(
-                                "field `{}` has already declared in the ancestor classes",
-                                class_field_name
+                                "field `{class_field_name}` has already declared in the ancestor classes"
                             ));
                         }
                     }
                     new_child_fields.push(to_be_added);
                 }
-                for (class_field_name, class_field_ty, mutable) in class_fields_def.iter() {
+                for (class_field_name, class_field_ty, mutable) in &*class_fields_def {
                     if !is_override.contains(class_field_name) {
                         new_child_fields.push((*class_field_name, *class_field_ty, *mutable));
                     }
@@ -1486,7 +1481,8 @@ impl TopLevelComposer {
         Ok(())
     }
 
-    /// step 5, analyze and call type inferencer to fill the `instance_to_stmt` of topleveldef::function
+    /// step 5, analyze and call type inferencer to fill the `instance_to_stmt` of
+    /// [`TopLevelDef::Function`]
     fn analyze_function_instance(&mut self) -> Result<(), String> {
         // first get the class constructor type correct for the following type check in function body
         // also do class field instantiation check
@@ -1558,7 +1554,7 @@ impl TopLevelComposer {
                             FuncArg {
                                 name: "msg".into(),
                                 ty: string,
-                                default_value: Some(SymbolValue::Str("".into())),
+                                default_value: Some(SymbolValue::Str(String::new())),
                             },
                             FuncArg {
                                 name: "param0".into(),
@@ -1577,15 +1573,15 @@ impl TopLevelComposer {
                             },
                         ],
                         ret: self_type,
-                        vars: Default::default(),
+                        vars: HashMap::default(),
                     }));
                     let cons_fun = TopLevelDef::Function {
                         name: format!("{}.{}", class_name, "__init__"),
                         simple_name: init_str_id,
                         signature,
-                        var_id: Default::default(),
-                        instance_to_symbol: Default::default(),
-                        instance_to_stmt: Default::default(),
+                        var_id: Vec::default(),
+                        instance_to_symbol: HashMap::default(),
+                        instance_to_stmt: HashMap::default(),
                         resolver: None,
                         codegen_callback: Some(Arc::new(GenCall::new(Box::new(exn_constructor)))),
                         loc: None,
@@ -1661,7 +1657,7 @@ impl TopLevelComposer {
             return Err(errors.into_iter().sorted().join("\n---------\n"));
         }
 
-        for (i, signature, id) in constructors.into_iter() {
+        for (i, signature, id) in constructors {
             if let TopLevelDef::Class { methods, .. } = &mut *self.definition_ast_list[i].0.write()
             {
                 methods.push((
@@ -1748,13 +1744,13 @@ impl TopLevelComposer {
                             })
                             .multi_cartesian_product()
                             .collect_vec();
-                        let mut result: Vec<HashMap<u32, Type>> = Default::default();
+                        let mut result: Vec<HashMap<u32, Type>> = Vec::default();
                         for comb in var_combs {
-                            result.push(vars.keys().cloned().zip(comb).collect());
+                            result.push(vars.keys().copied().zip(comb).collect());
                         }
                         // NOTE: if is empty, means no type var, append a empty subst, ok to do this?
                         if result.is_empty() {
-                            result.push(HashMap::new())
+                            result.push(HashMap::new());
                         }
                         (result, no_ranges)
                     };
@@ -1844,14 +1840,14 @@ impl TopLevelComposer {
                                     && matches!(&decorator_list[0].node,
                                         ast::ExprKind::Name{ id, .. } if id == &"extern".into())
                                 {
-                                    instance_to_symbol.insert("".into(), simple_name.to_string());
+                                    instance_to_symbol.insert(String::new(), simple_name.to_string());
                                     continue;
                                 }
                                 if !decorator_list.is_empty()
                                     && matches!(&decorator_list[0].node,
                                         ast::ExprKind::Name{ id, .. } if id == &"rpc".into())
                                 {
-                                    instance_to_symbol.insert("".into(), simple_name.to_string());
+                                    instance_to_symbol.insert(String::new(), simple_name.to_string());
                                     continue;
                                 }
                                 body
@@ -1867,15 +1863,14 @@ impl TopLevelComposer {
                         {
                             // check virtuals
                             let defs = ctx.definitions.read();
-                            for (subtype, base, loc) in inferencer.virtual_checks.iter() {
+                            for (subtype, base, loc) in &*inferencer.virtual_checks {
                                 let base_id = {
                                     let base = inferencer.unifier.get_ty(*base);
                                     if let TypeEnum::TObj { obj_id, .. } = &*base {
                                         *obj_id
                                     } else {
                                         return Err(format!(
-                                            "Base type should be a class (at {})",
-                                            loc
+                                            "Base type should be a class (at {loc})"
                                         ));
                                     }
                                 };
@@ -1887,8 +1882,7 @@ impl TopLevelComposer {
                                         let base_repr = inferencer.unifier.stringify(*base);
                                         let subtype_repr = inferencer.unifier.stringify(*subtype);
                                         return Err(format!(
-                                            "Expected a subtype of {}, but got {} (at {})",
-                                            base_repr, subtype_repr, loc
+                                            "Expected a subtype of {base_repr}, but got {subtype_repr} (at {loc})"
                                         ));
                                     }
                                 };
@@ -1900,8 +1894,7 @@ impl TopLevelComposer {
                                         let base_repr = inferencer.unifier.stringify(*base);
                                         let subtype_repr = inferencer.unifier.stringify(*subtype);
                                         return Err(format!(
-                                            "Expected a subtype of {}, but got {} (at {})",
-                                            base_repr, subtype_repr, loc
+                                            "Expected a subtype of {base_repr}, but got {subtype_repr} (at {loc})"
                                         ));
                                     }
                                 } else {
@@ -1922,7 +1915,7 @@ impl TopLevelComposer {
                                         unreachable!("must be class id here")
                                     }
                                 },
-                                &mut |id| format!("typevar{}", id),
+                                &mut |id| format!("typevar{id}"),
                                 &mut None,
                             );
                             return Err(format!(
@@ -1934,7 +1927,7 @@ impl TopLevelComposer {
                         }
 
                         instance_to_stmt.insert(
-                            get_subst_key(unifier, self_type, &subst, Some(&vars.keys().cloned().collect())),
+                            get_subst_key(unifier, self_type, &subst, Some(&vars.keys().copied().collect())),
                             FunInstance {
                                 body: Arc::new(fun_body),
                                 unifier_id: 0,
diff --git a/nac3core/src/toplevel/helper.rs b/nac3core/src/toplevel/helper.rs
index b7f60802e..6399f6dac 100644
--- a/nac3core/src/toplevel/helper.rs
+++ b/nac3core/src/toplevel/helper.rs
@@ -43,6 +43,7 @@ impl TopLevelDef {
 }
 
 impl TopLevelComposer {
+    #[must_use]
     pub fn make_primitives() -> (PrimitiveStore, Unifier) {
         let mut unifier = Unifier::new();
         let int32 = unifier.add_ty(TypeEnum::TObj {
@@ -134,22 +135,23 @@ impl TopLevelComposer {
         let primitives = PrimitiveStore {
             int32,
             int64,
+            uint32,
+            uint64,
             float,
             bool,
             none,
             range,
             str,
             exception,
-            uint32,
-            uint64,
             option,
         };
         crate::typecheck::magic_methods::set_primitives_magic_methods(&primitives, &mut unifier);
         (primitives, unifier)
     }
 
-    /// already include the definition_id of itself inside the ancestors vector
-    /// when first registering, the type_vars, fields, methods, ancestors are invalid
+    /// already include the `definition_id` of itself inside the ancestors vector
+    /// when first registering, the `type_vars`, fields, methods, ancestors are invalid
+    #[must_use]
     pub fn make_top_level_class_def(
         index: usize,
         resolver: Option<Arc<dyn SymbolResolver + Send + Sync>>,
@@ -160,10 +162,10 @@ impl TopLevelComposer {
         TopLevelDef::Class {
             name,
             object_id: DefinitionId(index),
-            type_vars: Default::default(),
-            fields: Default::default(),
-            methods: Default::default(),
-            ancestors: Default::default(),
+            type_vars: Vec::default(),
+            fields: Vec::default(),
+            methods: Vec::default(),
+            ancestors: Vec::default(),
             constructor,
             resolver,
             loc,
@@ -171,6 +173,7 @@ impl TopLevelComposer {
     }
 
     /// when first registering, the type is a invalid value
+    #[must_use]
     pub fn make_top_level_function_def(
         name: String,
         simple_name: StrRef,
@@ -182,15 +185,16 @@ impl TopLevelComposer {
             name,
             simple_name,
             signature: ty,
-            var_id: Default::default(),
-            instance_to_symbol: Default::default(),
-            instance_to_stmt: Default::default(),
+            var_id: Vec::default(),
+            instance_to_symbol: HashMap::default(),
+            instance_to_stmt: HashMap::default(),
             resolver,
             codegen_callback: None,
             loc,
         }
     }
 
+    #[must_use]
     pub fn make_class_method_name(mut class_name: String, method_name: &str) -> String {
         class_name.push('.');
         class_name.push_str(method_name);
@@ -206,7 +210,7 @@ impl TopLevelComposer {
                 return Ok((*ty, *def_id));
             }
         }
-        Err(format!("no method {} in the current class", method_name))
+        Err(format!("no method {method_name} in the current class"))
     }
 
     /// get all base class def id of a class, excluding itself. \
@@ -257,17 +261,17 @@ impl TopLevelComposer {
         let child_def = temp_def_list.get(child_id.0).unwrap();
         let child_def = child_def.read();
         if let TopLevelDef::Class { ancestors, .. } = &*child_def {
-            if !ancestors.is_empty() {
-                Some(ancestors[0].clone())
-            } else {
+            if ancestors.is_empty() {
                 None
+            } else {
+                Some(ancestors[0].clone())
             }
         } else {
             unreachable!("child must be top level class def")
         }
     }
 
-    /// get the var_id of a given TVar type
+    /// get the `var_id` of a given `TVar` type
     pub fn get_var_id(var_ty: Type, unifier: &mut Unifier) -> Result<u32, String> {
         if let TypeEnum::TVar { id, .. } = unifier.get_ty(var_ty).as_ref() {
             Ok(*id)
@@ -376,14 +380,14 @@ impl TopLevelComposer {
                 ast::StmtKind::If { body, orelse, .. } => {
                     let inited_for_sure = Self::get_all_assigned_field(body.as_slice())?
                         .intersection(&Self::get_all_assigned_field(orelse.as_slice())?)
-                        .cloned()
+                        .copied()
                         .collect::<HashSet<_>>();
                     result.extend(inited_for_sure);
                 }
                 ast::StmtKind::Try { body, orelse, finalbody, .. } => {
                     let inited_for_sure = Self::get_all_assigned_field(body.as_slice())?
                         .intersection(&Self::get_all_assigned_field(orelse.as_slice())?)
-                        .cloned()
+                        .copied()
                         .collect::<HashSet<_>>();
                     result.extend(inited_for_sure);
                     result.extend(Self::get_all_assigned_field(finalbody.as_slice())?);
@@ -391,9 +395,9 @@ impl TopLevelComposer {
                 ast::StmtKind::With { body, .. } => {
                     result.extend(Self::get_all_assigned_field(body.as_slice())?);
                 }
-                ast::StmtKind::Pass { .. } => {}
-                ast::StmtKind::Assert { .. } => {}
-                ast::StmtKind::Expr { .. } => {}
+                ast::StmtKind::Pass { .. }
+                | ast::StmtKind::Assert { .. }
+                | ast::StmtKind::Expr { .. } => {}
 
                 _ => {
                     unimplemented!()
@@ -448,14 +452,14 @@ impl TopLevelComposer {
         }
 
         let found = val.get_type_annotation(primitive, unifier);
-        if !is_compatible(&found, ty, unifier, primitive) {
+        if is_compatible(&found, ty, unifier, primitive) {
+            Ok(())
+        } else {
             Err(format!(
                 "incompatible default parameter type, expect {}, found {}",
                 ty.stringify(unifier),
                 found.stringify(unifier),
             ))
-        } else {
-            Ok(())
         }
     }
 }
@@ -470,7 +474,7 @@ pub fn parse_parameter_default_value(
                 if let Ok(v) = (*v).try_into() {
                     Ok(SymbolValue::I32(v))
                 } else {
-                    Err(format!("integer value out of range at {}", loc))
+                    Err(format!("integer value out of range at {loc}"))
                 }
             }
             Constant::Float(v) => Ok(SymbolValue::Double(*v)),
@@ -479,8 +483,7 @@ pub fn parse_parameter_default_value(
                 tuple.iter().map(|x| handle_constant(x, loc)).collect::<Result<Vec<_>, _>>()?,
             )),
             Constant::None => Err(format!(
-                "`None` is not supported, use `none` for option type instead ({})",
-                loc
+                "`None` is not supported, use `none` for option type instead ({loc})"
             )),
             _ => unimplemented!("this constant is not supported at {}", loc),
         }
diff --git a/nac3core/src/toplevel/mod.rs b/nac3core/src/toplevel/mod.rs
index 6b9566201..c62c5c0a1 100644
--- a/nac3core/src/toplevel/mod.rs
+++ b/nac3core/src/toplevel/mod.rs
@@ -3,7 +3,6 @@ use std::{
     collections::{HashMap, HashSet},
     fmt::Debug,
     iter::FromIterator,
-    ops::{Deref, DerefMut},
     sync::Arc,
 };
 
@@ -49,6 +48,7 @@ pub struct GenCall {
 }
 
 impl GenCall {
+    #[must_use]
     pub fn new(fp: GenCallCallback) -> GenCall {
         GenCall { fp }
     }
diff --git a/nac3core/src/toplevel/type_annotation.rs b/nac3core/src/toplevel/type_annotation.rs
index 3020abb0a..549227762 100644
--- a/nac3core/src/toplevel/type_annotation.rs
+++ b/nac3core/src/toplevel/type_annotation.rs
@@ -33,17 +33,16 @@ impl TypeAnnotation {
         match self {
             Primitive(ty) | TypeVar(ty) => unifier.stringify(*ty),
             CustomClass { id, params } => {
-                let class_name = match unifier.top_level {
-                    Some(ref top) => {
-                        if let TopLevelDef::Class { name, .. } =
-                            &*top.definitions.read()[id.0].read()
-                        {
-                            (*name).into()
-                        } else {
-                            unreachable!()
-                        }
+                let class_name = if let Some(ref top) = unifier.top_level {
+                    if let TopLevelDef::Class { name, .. } =
+                        &*top.definitions.read()[id.0].read()
+                    {
+                        (*name).into()
+                    } else {
+                        unreachable!()
                     }
-                    None => format!("class_def_{}", id.0),
+                } else {
+                    format!("class_def_{}", id.0)
                 };
                 format!(
                     "{}{}",
@@ -51,9 +50,9 @@ impl TypeAnnotation {
                     {
                         let param_list = params.iter().map(|p| p.stringify(unifier)).collect_vec().join(", ");
                         if param_list.is_empty() {
-                            "".into()
+                            String::new()
                         } else {
-                            format!("[{}]", param_list)
+                            format!("[{param_list}]")
                         }
                     }
                 )
@@ -68,12 +67,12 @@ impl TypeAnnotation {
     }
 }
 
-/// Parses an AST expression `expr` into a [TypeAnnotation].
+/// Parses an AST expression `expr` into a [`TypeAnnotation`].
 ///
-/// * `locked` - A [HashMap] containing the IDs of known definitions, mapped to a [Vec] of all
+/// * `locked` - A [`HashMap`] containing the IDs of known definitions, mapped to a [`Vec`] of all
 /// generic variables associated with the definition.
 /// * `type_var` - The type variable associated with the type argument currently being parsed. Pass
-/// [None] when this function is invoked externally.
+/// [`None`] when this function is invoked externally.
 pub fn parse_ast_to_type_annotation_kinds<T>(
     resolver: &(dyn SymbolResolver + Send + Sync),
     top_level_defs: &[Arc<RwLock<TopLevelDef>>],
@@ -102,7 +101,7 @@ pub fn parse_ast_to_type_annotation_kinds<T>(
         } else if id == &"str".into() {
             Ok(TypeAnnotation::Primitive(primitives.str))
         } else if id == &"Exception".into() {
-            Ok(TypeAnnotation::CustomClass { id: DefinitionId(7), params: Default::default() })
+            Ok(TypeAnnotation::CustomClass { id: DefinitionId(7), params: Vec::default() })
         } else if let Ok(obj_id) = resolver.get_identifier_def(*id) {
             let type_vars = {
                 let def_read = top_level_defs[obj_id.0].try_read();
@@ -356,7 +355,7 @@ pub fn get_type_from_type_annotation_kinds(
     match ann {
         TypeAnnotation::CustomClass { id: obj_id, params } => {
             let def_read = top_level_defs[obj_id.0].read();
-            let class_def: &TopLevelDef = def_read.deref();
+            let class_def: &TopLevelDef = &def_read;
             let TopLevelDef::Class { fields, methods, type_vars, .. } = class_def else {
                 unreachable!("should be class def here")
             };
@@ -406,8 +405,8 @@ pub fn get_type_from_type_annotation_kinds(
                                     "cannot apply type {} to type variable with id {:?}",
                                     unifier.internal_stringify(
                                         p,
-                                        &mut |id| format!("class{}", id),
-                                        &mut |id| format!("typevar{}", id),
+                                        &mut |id| format!("class{id}"),
+                                        &mut |id| format!("typevar{id}"),
                                         &mut None
                                     ),
                                     *id
@@ -521,9 +520,10 @@ pub fn get_type_from_type_annotation_kinds(
 /// considered to be type variables associated with the class \
 /// \
 /// But note that here we do not make a duplication of `T`, `V`, we directly
-/// use them as they are in the TopLevelDef::Class since those in the
-/// TopLevelDef::Class.type_vars will be substitute later when seeing applications/instantiations
+/// use them as they are in the [`TopLevelDef::Class`] since those in the
+/// `TopLevelDef::Class.type_vars` will be substitute later when seeing applications/instantiations
 /// the Type of their fields and methods will also be subst when application/instantiation
+#[must_use]
 pub fn make_self_type_annotation(type_vars: &[Type], object_id: DefinitionId) -> TypeAnnotation {
     TypeAnnotation::CustomClass {
         id: object_id,
@@ -534,21 +534,19 @@ pub fn make_self_type_annotation(type_vars: &[Type], object_id: DefinitionId) ->
 /// get all the occurences of type vars contained in a type annotation
 /// e.g. `A[int, B[T], V, virtual[C[G]]]` => [T, V, G]
 /// this function will not make a duplicate of type var
+#[must_use]
 pub fn get_type_var_contained_in_type_annotation(ann: &TypeAnnotation) -> Vec<TypeAnnotation> {
     let mut result: Vec<TypeAnnotation> = Vec::new();
     match ann {
         TypeAnnotation::TypeVar(..) => result.push(ann.clone()),
-        TypeAnnotation::Virtual(ann) => {
-            result.extend(get_type_var_contained_in_type_annotation(ann.as_ref()))
+        TypeAnnotation::Virtual(ann) | TypeAnnotation::List(ann) => {
+            result.extend(get_type_var_contained_in_type_annotation(ann.as_ref()));
         }
         TypeAnnotation::CustomClass { params, .. } => {
             for p in params {
                 result.extend(get_type_var_contained_in_type_annotation(p));
             }
         }
-        TypeAnnotation::List(ann) => {
-            result.extend(get_type_var_contained_in_type_annotation(ann.as_ref()))
-        }
         TypeAnnotation::Tuple(anns) => {
             for a in anns {
                 result.extend(get_type_var_contained_in_type_annotation(a));
@@ -569,9 +567,9 @@ pub fn check_overload_type_annotation_compatible(
         (TypeAnnotation::Primitive(a), TypeAnnotation::Primitive(b)) => a == b,
         (TypeAnnotation::TypeVar(a), TypeAnnotation::TypeVar(b)) => {
             let a = unifier.get_ty(*a);
-            let a = a.deref();
+            let a = &*a;
             let b = unifier.get_ty(*b);
-            let b = b.deref();
+            let b = &*b;
             if let (
                 TypeEnum::TVar { id: a, fields: None, .. },
                 TypeEnum::TVar { id: b, fields: None, .. },
diff --git a/nac3core/src/typecheck/function_check.rs b/nac3core/src/typecheck/function_check.rs
index b7e0e5b83..212646c3c 100644
--- a/nac3core/src/typecheck/function_check.rs
+++ b/nac3core/src/typecheck/function_check.rs
@@ -30,7 +30,7 @@ impl<'a> Inferencer<'a> {
                 Ok(())
             }
             ExprKind::Tuple { elts, .. } => {
-                for elt in elts.iter() {
+                for elt in elts {
                     self.check_pattern(elt, defined_identifiers)?;
                     self.should_have_value(elt)?;
                 }
@@ -98,7 +98,7 @@ impl<'a> Inferencer<'a> {
             ExprKind::List { elts, .. }
             | ExprKind::Tuple { elts, .. }
             | ExprKind::BoolOp { values: elts, .. } => {
-                for elt in elts.iter() {
+                for elt in elts {
                     self.check_expr(elt, defined_identifiers)?;
                     self.should_have_value(elt)?;
                 }
@@ -116,9 +116,8 @@ impl<'a> Inferencer<'a> {
                 // Check whether a bitwise shift has a negative RHS constant value
                 if *op == LShift || *op == RShift {
                     if let ExprKind::Constant { value, .. } = &right.node {
-                        let rhs_val = match value {
-                            Constant::Int(v) => v,
-                            _ => unreachable!(),
+                        let Constant::Int(rhs_val) = value else {
+                            unreachable!()
                         };
 
                         if *rhs_val < 0 {
@@ -158,7 +157,7 @@ impl<'a> Inferencer<'a> {
             }
             ExprKind::Lambda { args, body } => {
                 let mut defined_identifiers = defined_identifiers.clone();
-                for arg in args.args.iter() {
+                for arg in &args.args {
                     // TODO: should we check the types here?
                     if !defined_identifiers.contains(&arg.node.arg) {
                         defined_identifiers.insert(arg.node.arg);
@@ -207,13 +206,13 @@ impl<'a> Inferencer<'a> {
                 self.check_expr(iter, defined_identifiers)?;
                 self.should_have_value(iter)?;
                 let mut local_defined_identifiers = defined_identifiers.clone();
-                for stmt in orelse.iter() {
+                for stmt in orelse {
                     self.check_stmt(stmt, &mut local_defined_identifiers)?;
                 }
                 let mut local_defined_identifiers = defined_identifiers.clone();
                 self.check_pattern(target, &mut local_defined_identifiers)?;
                 self.should_have_value(target)?;
-                for stmt in body.iter() {
+                for stmt in body {
                     self.check_stmt(stmt, &mut local_defined_identifiers)?;
                 }
                 Ok(false)
@@ -226,7 +225,7 @@ impl<'a> Inferencer<'a> {
                 let body_returned = self.check_block(body, &mut body_identifiers)?;
                 let orelse_returned = self.check_block(orelse, &mut orelse_identifiers)?;
 
-                for ident in body_identifiers.iter() {
+                for ident in &body_identifiers {
                     if !defined_identifiers.contains(ident) && orelse_identifiers.contains(ident) {
                         defined_identifiers.insert(*ident);
                     }
@@ -243,7 +242,7 @@ impl<'a> Inferencer<'a> {
             }
             StmtKind::With { items, body, .. } => {
                 let mut new_defined_identifiers = defined_identifiers.clone();
-                for item in items.iter() {
+                for item in items {
                     self.check_expr(&item.context_expr, defined_identifiers)?;
                     if let Some(var) = item.optional_vars.as_ref() {
                         self.check_pattern(var, &mut new_defined_identifiers)?;
@@ -255,7 +254,7 @@ impl<'a> Inferencer<'a> {
             StmtKind::Try { body, handlers, orelse, finalbody, .. } => {
                 self.check_block(body, &mut defined_identifiers.clone())?;
                 self.check_block(orelse, &mut defined_identifiers.clone())?;
-                for handler in handlers.iter() {
+                for handler in handlers {
                     let mut defined_identifiers = defined_identifiers.clone();
                     let ast::ExcepthandlerKind::ExceptHandler { name, body, .. } = &handler.node;
                     if let Some(name) = name {
@@ -312,7 +311,7 @@ impl<'a> Inferencer<'a> {
         let mut ret = false;
         for stmt in block {
             if ret {
-                println!("warning: dead code at {:?}\n", stmt.location)
+                println!("warning: dead code at {:?}\n", stmt.location);
             }
             if self.check_stmt(stmt, defined_identifiers)? {
                 ret = true;
diff --git a/nac3core/src/typecheck/magic_methods.rs b/nac3core/src/typecheck/magic_methods.rs
index 0593cf6d5..9d92c08c6 100644
--- a/nac3core/src/typecheck/magic_methods.rs
+++ b/nac3core/src/typecheck/magic_methods.rs
@@ -7,6 +7,7 @@ use nac3parser::ast::{Cmpop, Operator, Unaryop};
 use std::collections::HashMap;
 use std::rc::Rc;
 
+#[must_use]
 pub fn binop_name(op: &Operator) -> &'static str {
     match op {
         Operator::Add => "__add__",
@@ -25,6 +26,7 @@ pub fn binop_name(op: &Operator) -> &'static str {
     }
 }
 
+#[must_use]
 pub fn binop_assign_name(op: &Operator) -> &'static str {
     match op {
         Operator::Add => "__iadd__",
@@ -43,6 +45,7 @@ pub fn binop_assign_name(op: &Operator) -> &'static str {
     }
 }
 
+#[must_use]
 pub fn unaryop_name(op: &Unaryop) -> &'static str {
     match op {
         Unaryop::UAdd => "__pos__",
@@ -52,6 +55,7 @@ pub fn unaryop_name(op: &Unaryop) -> &'static str {
     }
 }
 
+#[must_use]
 pub fn comparison_name(op: &Cmpop) -> Option<&'static str> {
     match op {
         Cmpop::Lt => Some("__lt__"),
@@ -183,7 +187,7 @@ pub fn impl_cmpop(
     });
 }
 
-/// Add, Sub, Mult
+/// `Add`, `Sub`, `Mult`
 pub fn impl_basic_arithmetic(
     unifier: &mut Unifier,
     store: &PrimitiveStore,
@@ -198,10 +202,10 @@ pub fn impl_basic_arithmetic(
         other_ty,
         ret_ty,
         &[Operator::Add, Operator::Sub, Operator::Mult],
-    )
+    );
 }
 
-/// Pow
+/// `Pow`
 pub fn impl_pow(
     unifier: &mut Unifier,
     store: &PrimitiveStore,
@@ -209,10 +213,10 @@ pub fn impl_pow(
     other_ty: &[Type],
     ret_ty: Type,
 ) {
-    impl_binop(unifier, store, ty, other_ty, ret_ty, &[Operator::Pow])
+    impl_binop(unifier, store, ty, other_ty, ret_ty, &[Operator::Pow]);
 }
 
-/// BitOr, BitXor, BitAnd
+/// `BitOr`, `BitXor`, `BitAnd`
 pub fn impl_bitwise_arithmetic(unifier: &mut Unifier, store: &PrimitiveStore, ty: Type) {
     impl_binop(
         unifier,
@@ -221,20 +225,20 @@ pub fn impl_bitwise_arithmetic(unifier: &mut Unifier, store: &PrimitiveStore, ty
         &[ty],
         ty,
         &[Operator::BitAnd, Operator::BitOr, Operator::BitXor],
-    )
+    );
 }
 
-/// LShift, RShift
+/// `LShift`, `RShift`
 pub fn impl_bitwise_shift(unifier: &mut Unifier, store: &PrimitiveStore, ty: Type) {
     impl_binop(unifier, store, ty, &[store.int32, store.uint32], ty, &[Operator::LShift, Operator::RShift]);
 }
 
-/// Div
+/// `Div`
 pub fn impl_div(unifier: &mut Unifier, store: &PrimitiveStore, ty: Type, other_ty: &[Type]) {
-    impl_binop(unifier, store, ty, other_ty, store.float, &[Operator::Div])
+    impl_binop(unifier, store, ty, other_ty, store.float, &[Operator::Div]);
 }
 
-/// FloorDiv
+/// `FloorDiv`
 pub fn impl_floordiv(
     unifier: &mut Unifier,
     store: &PrimitiveStore,
@@ -242,10 +246,10 @@ pub fn impl_floordiv(
     other_ty: &[Type],
     ret_ty: Type,
 ) {
-    impl_binop(unifier, store, ty, other_ty, ret_ty, &[Operator::FloorDiv])
+    impl_binop(unifier, store, ty, other_ty, ret_ty, &[Operator::FloorDiv]);
 }
 
-/// Mod
+/// `Mod`
 pub fn impl_mod(
     unifier: &mut Unifier,
     store: &PrimitiveStore,
@@ -253,25 +257,25 @@ pub fn impl_mod(
     other_ty: &[Type],
     ret_ty: Type,
 ) {
-    impl_binop(unifier, store, ty, other_ty, ret_ty, &[Operator::Mod])
+    impl_binop(unifier, store, ty, other_ty, ret_ty, &[Operator::Mod]);
 }
 
-/// UAdd, USub
+/// `UAdd`, `USub`
 pub fn impl_sign(unifier: &mut Unifier, _store: &PrimitiveStore, ty: Type) {
-    impl_unaryop(unifier, ty, ty, &[Unaryop::UAdd, Unaryop::USub])
+    impl_unaryop(unifier, ty, ty, &[Unaryop::UAdd, Unaryop::USub]);
 }
 
-/// Invert
+/// `Invert`
 pub fn impl_invert(unifier: &mut Unifier, _store: &PrimitiveStore, ty: Type) {
-    impl_unaryop(unifier, ty, ty, &[Unaryop::Invert])
+    impl_unaryop(unifier, ty, ty, &[Unaryop::Invert]);
 }
 
-/// Not
+/// `Not`
 pub fn impl_not(unifier: &mut Unifier, store: &PrimitiveStore, ty: Type) {
-    impl_unaryop(unifier, ty, store.bool, &[Unaryop::Not])
+    impl_unaryop(unifier, ty, store.bool, &[Unaryop::Not]);
 }
 
-/// Lt, LtE, Gt, GtE
+/// `Lt`, `LtE`, `Gt`, `GtE`
 pub fn impl_comparison(unifier: &mut Unifier, store: &PrimitiveStore, ty: Type, other_ty: Type) {
     impl_cmpop(
         unifier,
@@ -279,12 +283,12 @@ pub fn impl_comparison(unifier: &mut Unifier, store: &PrimitiveStore, ty: Type,
         ty,
         other_ty,
         &[Cmpop::Lt, Cmpop::Gt, Cmpop::LtE, Cmpop::GtE],
-    )
+    );
 }
 
-/// Eq, NotEq
+/// `Eq`, `NotEq`
 pub fn impl_eq(unifier: &mut Unifier, store: &PrimitiveStore, ty: Type) {
-    impl_cmpop(unifier, store, ty, ty, &[Cmpop::Eq, Cmpop::NotEq])
+    impl_cmpop(unifier, store, ty, ty, &[Cmpop::Eq, Cmpop::NotEq]);
 }
 
 pub fn set_primitives_magic_methods(store: &PrimitiveStore, unifier: &mut Unifier) {
diff --git a/nac3core/src/typecheck/type_error.rs b/nac3core/src/typecheck/type_error.rs
index a12098934..ac36b331a 100644
--- a/nac3core/src/typecheck/type_error.rs
+++ b/nac3core/src/typecheck/type_error.rs
@@ -43,15 +43,18 @@ pub struct TypeError {
 }
 
 impl TypeError {
+    #[must_use]
     pub fn new(kind: TypeErrorKind, loc: Option<Location>) -> TypeError {
         TypeError { kind, loc }
     }
 
+    #[must_use]
     pub fn at(mut self, loc: Option<Location>) -> TypeError {
         self.loc = self.loc.or(loc);
         self
     }
 
+    #[must_use]
     pub fn to_display(self, unifier: &Unifier) -> DisplayTypeError {
         DisplayTypeError { err: self, unifier }
     }
@@ -64,8 +67,8 @@ pub struct DisplayTypeError<'a> {
 
 fn loc_to_str(loc: Option<Location>) -> String {
     match loc {
-        Some(loc) => format!("(in {})", loc),
-        None => "".to_string(),
+        Some(loc) => format!("(in {loc})"),
+        None => String::new(),
     }
 }
 
@@ -75,21 +78,20 @@ impl<'a> Display for DisplayTypeError<'a> {
         let mut notes = Some(HashMap::new());
         match &self.err.kind {
             TooManyArguments { expected, got } => {
-                write!(f, "Too many arguments. Expected {} but got {}", expected, got)
+                write!(f, "Too many arguments. Expected {expected} but got {got}")
             }
             MissingArgs(args) => {
-                write!(f, "Missing arguments: {}", args)
+                write!(f, "Missing arguments: {args}")
             }
             UnknownArgName(name) => {
-                write!(f, "Unknown argument name: {}", name)
+                write!(f, "Unknown argument name: {name}")
             }
             IncorrectArgType { name, expected, got } => {
                 let expected = self.unifier.stringify_with_notes(*expected, &mut notes);
                 let got = self.unifier.stringify_with_notes(*got, &mut notes);
                 write!(
                     f,
-                    "Incorrect argument type for {}. Expected {}, but got {}",
-                    name, expected, got
+                    "Incorrect argument type for {name}. Expected {expected}, but got {got}"
                 )
             }
             FieldUnificationError { field, types, loc } => {
@@ -126,7 +128,7 @@ impl<'a> Display for DisplayTypeError<'a> {
                         );
                         if let Some(loc) = loc {
                             result?;
-                            write!(f, " (in {})", loc)?;
+                            write!(f, " (in {loc})")?;
                             return Ok(());
                         }
                         result
@@ -136,12 +138,12 @@ impl<'a> Display for DisplayTypeError<'a> {
                     {
                         let t1 = self.unifier.stringify_with_notes(*t1, &mut notes);
                         let t2 = self.unifier.stringify_with_notes(*t2, &mut notes);
-                        write!(f, "Tuple length mismatch: got {} and {}", t1, t2)
+                        write!(f, "Tuple length mismatch: got {t1} and {t2}")
                     }
                     _ => {
                         let t1 = self.unifier.stringify_with_notes(*t1, &mut notes);
                         let t2 = self.unifier.stringify_with_notes(*t2, &mut notes);
-                        write!(f, "Incompatible types: {} and {}", t1, t2)
+                        write!(f, "Incompatible types: {t1} and {t2}")
                     }
                 }
             }
@@ -150,18 +152,17 @@ impl<'a> Display for DisplayTypeError<'a> {
                     write!(f, "Cannot assign to an element of a tuple")
                 } else {
                     let t = self.unifier.stringify_with_notes(*t, &mut notes);
-                    write!(f, "Cannot assign to field {} of {}, which is immutable", name, t)
+                    write!(f, "Cannot assign to field {name} of {t}, which is immutable")
                 }
             }
             NoSuchField(name, t) => {
                 let t = self.unifier.stringify_with_notes(*t, &mut notes);
-                write!(f, "`{}::{}` field/method does not exist", t, name)
+                write!(f, "`{t}::{name}` field/method does not exist")
             }
             TupleIndexOutOfBounds { index, len } => {
                 write!(
                     f,
-                    "Tuple index out of bounds. Got {} but tuple has only {} elements",
-                    index, len
+                    "Tuple index out of bounds. Got {index} but tuple has only {len} elements"
                 )
             }
             RequiresTypeAnn => {
@@ -172,13 +173,13 @@ impl<'a> Display for DisplayTypeError<'a> {
             }
         }?;
         if let Some(loc) = self.err.loc {
-            write!(f, " at {}", loc)?;
+            write!(f, " at {loc}")?;
         }
         let notes = notes.unwrap();
         if !notes.is_empty() {
             write!(f, "\n\nNotes:")?;
             for line in notes.values() {
-                write!(f, "\n    {}", line)?;
+                write!(f, "\n    {line}")?;
             }
         }
         Ok(())
diff --git a/nac3core/src/typecheck/type_inferencer/mod.rs b/nac3core/src/typecheck/type_inferencer/mod.rs
index a0c619260..a7b73de2a 100644
--- a/nac3core/src/typecheck/type_inferencer/mod.rs
+++ b/nac3core/src/typecheck/type_inferencer/mod.rs
@@ -65,20 +65,20 @@ struct NaiveFolder();
 impl Fold<()> for NaiveFolder {
     type TargetU = Option<Type>;
     type Error = String;
-    fn map_user(&mut self, _: ()) -> Result<Self::TargetU, Self::Error> {
+    fn map_user(&mut self, (): ()) -> Result<Self::TargetU, Self::Error> {
         Ok(None)
     }
 }
 
 fn report_error<T>(msg: &str, location: Location) -> Result<T, String> {
-    Err(format!("{} at {}", msg, location))
+    Err(format!("{msg} at {location}"))
 }
 
 impl<'a> Fold<()> for Inferencer<'a> {
     type TargetU = Option<Type>;
     type Error = String;
 
-    fn map_user(&mut self, _: ()) -> Result<Self::TargetU, Self::Error> {
+    fn map_user(&mut self, (): ()) -> Result<Self::TargetU, Self::Error> {
         Ok(None)
     }
 
@@ -138,7 +138,7 @@ impl<'a> Fold<()> for Inferencer<'a> {
                 {
                     let top_level_defs = self.top_level.definitions.read();
                     let mut naive_folder = NaiveFolder();
-                    for handler in handlers.into_iter() {
+                    for handler in handlers {
                         let ast::ExcepthandlerKind::ExceptHandler { type_, name, body } =
                             handler.node;
                         let type_ = if let Some(type_) = type_ {
@@ -226,65 +226,65 @@ impl<'a> Fold<()> for Inferencer<'a> {
                 }
             }
             ast::StmtKind::Assign { ref mut targets, ref config_comment, .. } => {
-                for target in targets.iter_mut() {
+                for target in &mut *targets {
                     if let ExprKind::Attribute { ctx, .. } = &mut target.node {
                         *ctx = ExprContext::Store;
                     }
                 }
                 if targets.iter().all(|t| matches!(t.node, ExprKind::Name { .. })) {
-                    if let ast::StmtKind::Assign { targets, value, .. } = node.node {
-                        let value = self.fold_expr(*value)?;
-                        let value_ty = value.custom.unwrap();
-                        let targets: Result<Vec<_>, _> = targets
-                            .into_iter()
-                            .map(|target| {
-                                if let ExprKind::Name { id, ctx } = target.node {
-                                    self.defined_identifiers.insert(id);
-                                    let target_ty = if let Some(ty) = self.variable_mapping.get(&id)
-                                    {
-                                        *ty
-                                    } else {
-                                        let unifier = &mut self.unifier;
-                                        self.function_data
-                                            .resolver
-                                            .get_symbol_type(
-                                                unifier,
-                                                &self.top_level.definitions.read(),
-                                                self.primitives,
-                                                id,
-                                            )
-                                            .unwrap_or_else(|_| {
-                                                self.variable_mapping.insert(id, value_ty);
-                                                value_ty
-                                            })
-                                    };
-                                    let location = target.location;
-                                    self.unifier.unify(value_ty, target_ty).map(|_| Located {
-                                        location,
-                                        node: ExprKind::Name { id, ctx },
-                                        custom: Some(target_ty),
-                                    })
-                                } else {
-                                    unreachable!()
-                                }
-                            })
-                            .collect();
-                        let loc = node.location;
-                        let targets = targets
-                            .map_err(|e| e.at(Some(loc)).to_display(self.unifier).to_string())?;
-                        return Ok(Located {
-                            location: node.location,
-                            node: ast::StmtKind::Assign {
-                                targets,
-                                value: Box::new(value),
-                                type_comment: None,
-                                config_comment: config_comment.clone(),
-                            },
-                            custom: None,
-                        });
-                    } else {
+                    let ast::StmtKind::Assign { targets, value, .. } = node.node else {
                         unreachable!()
-                    }
+                    };
+
+                    let value = self.fold_expr(*value)?;
+                    let value_ty = value.custom.unwrap();
+                    let targets: Result<Vec<_>, _> = targets
+                        .into_iter()
+                        .map(|target| {
+                            if let ExprKind::Name { id, ctx } = target.node {
+                                self.defined_identifiers.insert(id);
+                                let target_ty = if let Some(ty) = self.variable_mapping.get(&id)
+                                {
+                                    *ty
+                                } else {
+                                    let unifier: &mut Unifier = self.unifier;
+                                    self.function_data
+                                        .resolver
+                                        .get_symbol_type(
+                                            unifier,
+                                            &self.top_level.definitions.read(),
+                                            self.primitives,
+                                            id,
+                                        )
+                                        .unwrap_or_else(|_| {
+                                            self.variable_mapping.insert(id, value_ty);
+                                            value_ty
+                                        })
+                                };
+                                let location = target.location;
+                                self.unifier.unify(value_ty, target_ty).map(|()| Located {
+                                    location,
+                                    node: ExprKind::Name { id, ctx },
+                                    custom: Some(target_ty),
+                                })
+                            } else {
+                                unreachable!()
+                            }
+                        })
+                        .collect();
+                    let loc = node.location;
+                    let targets = targets
+                        .map_err(|e| e.at(Some(loc)).to_display(self.unifier).to_string())?;
+                    return Ok(Located {
+                        location: node.location,
+                        node: ast::StmtKind::Assign {
+                            targets,
+                            value: Box::new(value),
+                            type_comment: None,
+                            config_comment: config_comment.clone(),
+                        },
+                        custom: None,
+                    });
                 }
                 for target in targets {
                     self.infer_pattern(target)?;
@@ -292,7 +292,7 @@ impl<'a> Fold<()> for Inferencer<'a> {
                 fold::fold_stmt(self, node)?
             }
             ast::StmtKind::With { ref items, .. } => {
-                for item in items.iter() {
+                for item in items {
                     if let Some(var) = &item.optional_vars {
                         self.infer_pattern(var)?;
                     }
@@ -302,20 +302,21 @@ impl<'a> Fold<()> for Inferencer<'a> {
             _ => fold::fold_stmt(self, node)?,
         };
         match &stmt.node {
-            ast::StmtKind::For { .. } => {}
-            ast::StmtKind::Try { .. } => {}
+            ast::StmtKind::AnnAssign { .. }
+            | ast::StmtKind::Break { .. }
+            | ast::StmtKind::Continue { .. }
+            | ast::StmtKind::Expr { .. }
+            | ast::StmtKind::For { .. }
+            | ast::StmtKind::Pass { .. }
+            | ast::StmtKind::Try { .. } => {}
             ast::StmtKind::If { test, .. } | ast::StmtKind::While { test, .. } => {
                 self.unify(test.custom.unwrap(), self.primitives.bool, &test.location)?;
             }
             ast::StmtKind::Assign { targets, value, .. } => {
-                for target in targets.iter() {
+                for target in targets {
                     self.unify(target.custom.unwrap(), value.custom.unwrap(), &target.location)?;
                 }
             }
-            ast::StmtKind::AnnAssign { .. } | ast::StmtKind::Expr { .. } => {}
-            ast::StmtKind::Break { .. }
-            | ast::StmtKind::Continue { .. }
-            | ast::StmtKind::Pass { .. } => {}
             ast::StmtKind::Raise { exc, cause, .. } => {
                 if let Some(cause) = cause {
                     return report_error("raise ... from cause is not supported", cause.location);
@@ -334,13 +335,13 @@ impl<'a> Fold<()> for Inferencer<'a> {
                 }
             }
             ast::StmtKind::With { items, .. } => {
-                for item in items.iter() {
+                for item in items {
                     let ty = item.context_expr.custom.unwrap();
                     // if we can simply unify without creating new types...
                     let mut fast_path = false;
                     if let TypeEnum::TObj { fields, .. } = &*self.unifier.get_ty(ty) {
                         fast_path = true;
-                        if let Some(enter) = fields.get(&"__enter__".into()).cloned() {
+                        if let Some(enter) = fields.get(&"__enter__".into()).copied() {
                             if let TypeEnum::TFunc(signature) = &*self.unifier.get_ty(enter.0) {
                                 if !signature.args.is_empty() {
                                     return report_error(
@@ -368,7 +369,7 @@ impl<'a> Fold<()> for Inferencer<'a> {
                                 stmt.location,
                             );
                         }
-                        if let Some(exit) = fields.get(&"__exit__".into()).cloned() {
+                        if let Some(exit) = fields.get(&"__exit__".into()).copied() {
                             if let TypeEnum::TFunc(signature) = &*self.unifier.get_ty(exit.0) {
                                 if !signature.args.is_empty() {
                                     return report_error(
@@ -393,13 +394,13 @@ impl<'a> Fold<()> for Inferencer<'a> {
                                 || self.unifier.get_dummy_var().0,
                                 |var| var.custom.unwrap(),
                             ),
-                            vars: Default::default(),
+                            vars: HashMap::default(),
                         });
                         let enter = self.unifier.add_ty(enter);
                         let exit = TypeEnum::TFunc(FunSignature {
                             args: vec![],
                             ret: self.unifier.get_dummy_var().0,
-                            vars: Default::default(),
+                            vars: HashMap::default(),
                         });
                         let exit = self.unifier.add_ty(exit);
                         let mut fields = HashMap::new();
@@ -489,7 +490,7 @@ impl<'a> Fold<()> for Inferencer<'a> {
                             }
                             Err(e) => {
                                 return report_error(
-                                    &format!("type error at identifier `{}` ({})", id, e),
+                                    &format!("type error at identifier `{id}` ({e})"),
                                     expr.location,
                                 );
                             }
@@ -551,7 +552,7 @@ impl<'a> Inferencer<'a> {
                 Ok(())
             }
             ExprKind::Tuple { elts, .. } => {
-                for elt in elts.iter() {
+                for elt in elts {
                     self.infer_pattern(elt)?;
                 }
                 Ok(())
@@ -637,7 +638,7 @@ impl<'a> Inferencer<'a> {
         }
 
         let mut defined_identifiers = self.defined_identifiers.clone();
-        for arg in args.args.iter() {
+        for arg in &args.args {
             let name = &arg.node.arg;
             if !defined_identifiers.contains(name) {
                 defined_identifiers.insert(*name);
@@ -649,7 +650,7 @@ impl<'a> Inferencer<'a> {
             .map(|v| (v.node.arg, self.unifier.get_fresh_var(Some(v.node.arg), Some(v.location)).0))
             .collect();
         let mut variable_mapping = self.variable_mapping.clone();
-        variable_mapping.extend(fn_args.iter().cloned());
+        variable_mapping.extend(fn_args.iter().copied());
         let ret = self.unifier.get_dummy_var().0;
 
         let mut new_context = Inferencer {
@@ -670,7 +671,7 @@ impl<'a> Inferencer<'a> {
                 .map(|(k, ty)| FuncArg { name: *k, ty: *ty, default_value: None })
                 .collect(),
             ret,
-            vars: Default::default(),
+            vars: HashMap::default(),
         };
         let body = new_context.fold_expr(body)?;
         new_context.unify(fun.ret, body.custom.unwrap(), &location)?;
@@ -739,7 +740,7 @@ impl<'a> Inferencer<'a> {
         // iter should be a list of targets...
         // actually it should be an iterator of targets, but we don't have iter type for now
         // if conditions should be bool
-        for v in ifs.iter() {
+        for v in &ifs {
             new_context.unify(v.custom.unwrap(), new_context.primitives.bool, &v.location)?;
         }
 
@@ -926,12 +927,12 @@ impl<'a> Inferencer<'a> {
     }
 
     fn infer_identifier(&mut self, id: StrRef) -> InferenceResult {
-        if let Some(ty) = self.variable_mapping.get(&id) {
-            Ok(*ty)
+        Ok(if let Some(ty) = self.variable_mapping.get(&id) {
+            *ty
         } else {
             let variable_mapping = &mut self.variable_mapping;
-            let unifier = &mut self.unifier;
-            Ok(self
+            let unifier: &mut Unifier = self.unifier;
+            self
                 .function_data
                 .resolver
                 .get_symbol_type(unifier, &self.top_level.definitions.read(), self.primitives, id)
@@ -939,8 +940,8 @@ impl<'a> Inferencer<'a> {
                     let ty = unifier.get_dummy_var().0;
                     variable_mapping.insert(id, ty);
                     ty
-                }))
-        }
+                })
+        })
     }
 
     fn infer_constant(&mut self, constant: &ast::Constant, loc: &Location) -> InferenceResult {
@@ -971,7 +972,7 @@ impl<'a> Inferencer<'a> {
 
     fn infer_list(&mut self, elts: &[ast::Expr<Option<Type>>]) -> InferenceResult {
         let ty = self.unifier.get_dummy_var().0;
-        for t in elts.iter() {
+        for t in elts {
             self.unify(ty, t.custom.unwrap(), &t.location)?;
         }
         Ok(self.unifier.add_ty(TypeEnum::TList { ty }))
@@ -992,14 +993,13 @@ impl<'a> Inferencer<'a> {
         if let TypeEnum::TObj { fields, .. } = &*self.unifier.get_ty(ty) {
             // just a fast path
             match (fields.get(&attr), ctx == &ExprContext::Store) {
-                (Some((ty, true)), _) => Ok(*ty),
-                (Some((ty, false)), false) => Ok(*ty),
+                (Some((ty, true)), _) | (Some((ty, false)), false) => Ok(*ty),
                 (Some((_, false)), true) => {
-                    report_error(&format!("Field `{}` is immutable", attr), value.location)
+                    report_error(&format!("Field `{attr}` is immutable"), value.location)
                 }
                 (None, _) => {
                     let t = self.unifier.stringify(ty);
-                    report_error(&format!("`{}::{}` field/method does not exist", t, attr), value.location)
+                    report_error(&format!("`{t}::{attr}` field/method does not exist"), value.location)
                 },
             }
         } else {
diff --git a/nac3core/src/typecheck/typedef/mod.rs b/nac3core/src/typecheck/typedef/mod.rs
index 04d8df54b..1be280a21 100644
--- a/nac3core/src/typecheck/typedef/mod.rs
+++ b/nac3core/src/typecheck/typedef/mod.rs
@@ -97,8 +97,8 @@ impl From<i32> for RecordKey {
 impl Display for RecordKey {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         match self {
-            RecordKey::Str(s) => write!(f, "{}", s),
-            RecordKey::Int(i) => write!(f, "{}", i),
+            RecordKey::Str(s) => write!(f, "{s}"),
+            RecordKey::Int(i) => write!(f, "{i}"),
         }
     }
 }
@@ -111,6 +111,7 @@ pub struct RecordField {
 }
 
 impl RecordField {
+    #[must_use]
     pub fn new(ty: Type, mutable: bool, loc: Option<Location>) -> RecordField {
         RecordField { ty, mutable, loc }
     }
@@ -185,6 +186,7 @@ pub enum TypeEnum {
 }
 
 impl TypeEnum {
+    #[must_use]
     pub fn get_type_name(&self) -> &'static str {
         match self {
             TypeEnum::TRigidVar { .. } => "TRigidVar",
@@ -220,6 +222,7 @@ impl Default for Unifier {
 
 impl Unifier {
     /// Get an empty unifier
+    #[must_use]
     pub fn new() -> Unifier {
         Unifier {
             unification_table: UnificationTable::new(),
@@ -252,6 +255,7 @@ impl Unifier {
         }
     }
 
+    #[must_use]
     pub fn get_shared_unifier(&self) -> SharedUnifier {
         Arc::new(Mutex::new((
             self.unification_table.get_send(),
@@ -261,7 +265,7 @@ impl Unifier {
     }
 
     /// Register a type to the unifier.
-    /// Returns a key in the unification_table.
+    /// Returns a key in the `unification_table`.
     pub fn add_ty(&mut self, a: TypeEnum) -> Type {
         self.unification_table.new_key(Rc::new(a))
     }
@@ -294,6 +298,7 @@ impl Unifier {
         }
     }
 
+    #[must_use]
     pub fn get_call_signature_immutable(&self, id: CallId) -> Option<FunSignature> {
         let fun = self.calls.get(id.0).unwrap().fun.borrow().unwrap();
         if let TypeEnum::TFunc(sign) = &*self.get_ty_immutable(fun) {
@@ -307,11 +312,12 @@ impl Unifier {
         self.unification_table.get_representative(ty)
     }
 
-    /// Get the TypeEnum of a type.
+    /// Get the `TypeEnum` of a type.
     pub fn get_ty(&mut self, a: Type) -> Rc<TypeEnum> {
         self.unification_table.probe_value(a).clone()
     }
 
+    #[must_use]
     pub fn get_ty_immutable(&self, a: Type) -> Rc<TypeEnum> {
         self.unification_table.probe_value_immutable(a).clone()
     }
@@ -435,7 +441,7 @@ impl Unifier {
                             .map(|params| {
                                 self.subst(
                                     ty,
-                                    &zip(keys.iter().cloned(), params.iter().cloned()).collect(),
+                                    &zip(keys.iter().copied(), params.iter().copied()).collect(),
                                 )
                                 .unwrap_or(ty)
                             })
@@ -453,7 +459,7 @@ impl Unifier {
             TRigidVar { .. } | TConstant { .. } => true,
             TVar { .. } => allowed_typevars.iter().any(|b| self.unification_table.unioned(a, *b)),
             TCall { .. } => false,
-            TList { ty } => self.is_concrete(*ty, allowed_typevars),
+            TList { ty } | TVirtual { ty } => self.is_concrete(*ty, allowed_typevars),
             TTuple { ty } => ty.iter().all(|ty| self.is_concrete(*ty, allowed_typevars)),
             TObj { params: vars, .. } => {
                 vars.values().all(|ty| self.is_concrete(*ty, allowed_typevars))
@@ -461,7 +467,6 @@ impl Unifier {
             // functions are instantiated for each call sites, so the function type can contain
             // type variables.
             TFunc { .. } => true,
-            TVirtual { ty } => self.is_concrete(*ty, allowed_typevars),
         }
     }
 
@@ -522,7 +527,7 @@ impl Unifier {
                 TypeError::new(TypeErrorKind::IncorrectArgType { name, expected, got: *t }, *loc)
             })?;
         }
-        for (k, t) in kwargs.iter() {
+        for (k, t) in kwargs {
             if let Some(i) = required.iter().position(|v| v == k) {
                 required.remove(i);
             }
@@ -609,7 +614,7 @@ impl Unifier {
                     }
                     (Some(fields1), Some(fields2)) => {
                         let mut new_fields: Mapping<_, _> = fields2.clone();
-                        for (key, val1) in fields1.iter() {
+                        for (key, val1) in fields1 {
                             if let Some(val2) = fields2.get(key) {
                                 self.unify_impl(val1.ty, val2.ty, false).map_err(|_| {
                                     TypeError::new(
@@ -638,7 +643,7 @@ impl Unifier {
                 };
                 let intersection = self
                     .get_intersection(a, b)
-                    .map_err(|_| TypeError::new(TypeErrorKind::IncompatibleTypes(a, b), None))?
+                    .map_err(|()| TypeError::new(TypeErrorKind::IncompatibleTypes(a, b), None))?
                     .unwrap();
                 let range = if let TVar { range, .. } = &*self.get_ty(intersection) {
                     range.clone()
@@ -677,7 +682,7 @@ impl Unifier {
             }
             (TVar { fields: Some(fields), range, is_const_generic: false, .. }, TTuple { ty }) => {
                 let len = ty.len() as i32;
-                for (k, v) in fields.iter() {
+                for (k, v) in fields {
                     match *k {
                         RecordKey::Int(i) => {
                             if v.mutable {
@@ -706,10 +711,10 @@ impl Unifier {
                 self.set_a_to_b(a, x);
             }
             (TVar { fields: Some(fields), range, is_const_generic: false, .. }, TList { ty }) => {
-                for (k, v) in fields.iter() {
+                for (k, v) in fields {
                     match *k {
                         RecordKey::Int(_) => {
-                            self.unify_impl(v.ty, *ty, false).map_err(|e| e.at(v.loc))?
+                            self.unify_impl(v.ty, *ty, false).map_err(|e| e.at(v.loc))?;
                         }
                         RecordKey::Str(_) => {
                             return Err(TypeError::new(TypeErrorKind::NoSuchField(*k, b), v.loc))
@@ -767,7 +772,7 @@ impl Unifier {
                 self.set_a_to_b(a, b);
             }
             (TVar { fields: Some(map), range, .. }, TObj { fields, .. }) => {
-                for (k, field) in map.iter() {
+                for (k, field) in map {
                     match *k {
                         RecordKey::Str(s) => {
                             let (ty, mutable) = fields.get(&s).copied().ok_or_else(|| {
@@ -799,7 +804,7 @@ impl Unifier {
             (TVar { fields: Some(map), range, .. }, TVirtual { ty }) => {
                 let ty = self.get_ty(*ty);
                 if let TObj { fields, .. } = ty.as_ref() {
-                    for (k, field) in map.iter() {
+                    for (k, field) in map {
                         match *k {
                             RecordKey::Str(s) => {
                                 let (ty, _) = fields.get(&s).copied().ok_or_else(|| {
@@ -866,7 +871,7 @@ impl Unifier {
             (TCall(calls1), TCall(calls2)) => {
                 // we do not unify individual calls, instead we defer until the unification wtih a
                 // function definition.
-                let calls = calls1.iter().chain(calls2.iter()).cloned().collect();
+                let calls = calls1.iter().chain(calls2.iter()).copied().collect();
                 self.set_a_to_b(a, b);
                 self.unification_table.set_value(b, Rc::new(TCall(calls)));
             }
@@ -879,7 +884,7 @@ impl Unifier {
                     .rev()
                     .collect();
                 // we unify every calls to the function signature.
-                for c in calls.iter() {
+                for c in calls {
                     let call = self.calls[c.0].clone();
                     self.unify_call(&call, b, signature, &required)?;
                 }
@@ -912,9 +917,9 @@ impl Unifier {
             _ => {
                 if swapped {
                     return self.incompatible_types(a, b);
-                } else {
-                    self.unify_impl(b, a, true)?;
                 }
+
+                self.unify_impl(b, a, true)?;
             }
         }
         Ok(())
@@ -934,7 +939,7 @@ impl Unifier {
             ty,
             &mut |id| {
                 top_level.as_ref().map_or_else(
-                    || format!("{}", id),
+                    || format!("{id}"),
                     |top_level| {
                         if let TopLevelDef::Class { name, .. } =
                             &*top_level.definitions.read()[id].read()
@@ -946,7 +951,7 @@ impl Unifier {
                     },
                 )
             },
-            &mut |id| format!("typevar{}", id),
+            &mut |id| format!("typevar{id}"),
             notes,
         )
     }
@@ -989,7 +994,7 @@ impl Unifier {
                 if !range.is_empty() && notes.is_some() && !notes.as_ref().unwrap().contains_key(id)
                 {
                     // just in case if there is any cyclic dependency
-                    notes.as_mut().unwrap().insert(*id, "".into());
+                    notes.as_mut().unwrap().insert(*id, String::new());
                     let body = format!(
                         "{} ∈ {{{}}}",
                         n,
@@ -1022,15 +1027,15 @@ impl Unifier {
             }
             TypeEnum::TObj { obj_id, params, .. } => {
                 let name = obj_to_name(obj_id.0);
-                if !params.is_empty() {
+                if params.is_empty() {
+                    name
+                } else {
                     let params = params
                         .iter()
                         .map(|(_, v)| self.internal_stringify(*v, obj_to_name, var_to_name, notes));
                     // sort to preserve order
                     let mut params = params.sorted();
                     format!("{}[{}]", name, params.join(", "))
-                } else {
-                    name
                 }
             }
             TypeEnum::TCall { .. } => "call".to_owned(),
@@ -1056,7 +1061,7 @@ impl Unifier {
                     })
                     .join(", ");
                 let ret = self.internal_stringify(signature.ret, obj_to_name, var_to_name, notes);
-                format!("fn[[{}], {}]", params, ret)
+                format!("fn[[{params}], {ret}]")
             }
         }
     }
@@ -1066,7 +1071,7 @@ impl Unifier {
         let table = &mut self.unification_table;
         let ty_b = table.probe_value(b).clone();
         table.unify(a, b);
-        table.set_value(a, ty_b)
+        table.set_value(a, ty_b);
     }
 
     fn incompatible_types(&mut self, a: Type, b: Type) -> Result<(), TypeError> {
@@ -1079,7 +1084,7 @@ impl Unifier {
     fn instantiate_fun(&mut self, ty: Type, fun: &FunSignature) -> Type {
         let mut instantiated = true;
         let mut vars = Vec::new();
-        for (k, v) in fun.vars.iter() {
+        for (k, v) in &fun.vars {
             if let TypeEnum::TVar { id, name, loc, range, .. } =
                 self.unification_table.probe_value(*v).as_ref()
             {
@@ -1134,7 +1139,7 @@ impl Unifier {
         // should be safe to not implement the substitution for those variants.
         match &*ty {
             TypeEnum::TRigidVar { .. } => None,
-            TypeEnum::TVar { id, .. } => mapping.get(id).cloned(),
+            TypeEnum::TVar { id, .. } => mapping.get(id).copied(),
             TypeEnum::TTuple { ty } => {
                 let mut new_ty = Cow::from(ty);
                 for (i, t) in ty.iter().enumerate() {
@@ -1219,7 +1224,7 @@ impl Unifier {
         K: std::hash::Hash + Eq + Clone,
     {
         let mut map2 = None;
-        for (k, v) in map.iter() {
+        for (k, v) in map {
             if let Some(v1) = self.subst_impl(*v, mapping, cache) {
                 if map2.is_none() {
                     map2 = Some(map.clone());
@@ -1240,7 +1245,7 @@ impl Unifier {
         K: std::hash::Hash + Eq + Clone,
     {
         let mut map2 = None;
-        for (k, (v, mutability)) in map.iter() {
+        for (k, (v, mutability)) in map {
             if let Some(v1) = self.subst_impl(*v, mapping, cache) {
                 if map2.is_none() {
                     map2 = Some(map.clone());
@@ -1296,7 +1301,7 @@ impl Unifier {
                 if range.is_empty() {
                     Ok(Some(a))
                 } else {
-                    for v in range.iter() {
+                    for v in range {
                         let result = self.get_intersection(a, *v);
                         if let Ok(result) = result {
                             return Ok(result.or(Some(a)));
@@ -1338,7 +1343,7 @@ impl Unifier {
         if range.is_empty() {
             return Ok(None);
         }
-        for t in range.iter() {
+        for t in range {
             let result = self.get_intersection(*t, b);
             if let Ok(result) = result {
                 return Ok(result);
diff --git a/nac3standalone/src/main.rs b/nac3standalone/src/main.rs
index 4b69be7b5..c22bd56f9 100644
--- a/nac3standalone/src/main.rs
+++ b/nac3standalone/src/main.rs
@@ -393,7 +393,7 @@ fn main() {
     let threads = (0..threads)
         .map(|i| Box::new(DefaultCodeGenerator::new(format!("module{}", i), 64)))
         .collect();
-    let (registry, handles) = WorkerRegistry::create_workers(threads, top_level, &llvm_options, f);
+    let (registry, handles) = WorkerRegistry::create_workers(threads, top_level, &llvm_options, &f);
     registry.add_task(task);
     registry.wait_tasks_complete(handles);