[core] introduce models

nac3core/src/codegen/expr.rs

@@ -2886,31 +2886,7 @@ pub fn gen_expr<'ctx, G: CodeGenerator>(
             Some((_, Some(static_value), _)) => ValueEnum::Static(static_value.clone()),
             None => {
                 let resolver = ctx.resolver.clone();
-                let value = resolver.get_symbol_value(*id, ctx, generator).unwrap();
-
-                let globals = ctx
-                    .top_level
-                    .definitions
-                    .read()
-                    .iter()
-                    .filter_map(|def| {
-                        if let TopLevelDef::Variable { simple_name, ty, .. } = &*def.read() {
-                            Some((*simple_name, *ty))
-                        } else {
-                            None
-                        }
-                    })
-                    .collect_vec();
-
-                if let Some((_, ty)) = globals.iter().find(|(name, _)| name == id) {
-                    let ptr = value
-                        .to_basic_value_enum(ctx, generator, *ty)
-                        .map(BasicValueEnum::into_pointer_value)?;
-
-                    ctx.builder.build_load(ptr, id.to_string().as_str()).map(Into::into).unwrap()
-                } else {
-                    value
-                }
+                resolver.get_symbol_value(*id, ctx, generator).unwrap()
             }
         },
         ExprKind::List { elts, .. } => {

nac3core/src/codegen/mod.rs

@@ -46,6 +46,7 @@ pub mod extern_fns;
 mod generator;
 pub mod irrt;
 pub mod llvm_intrinsics;
+pub mod model;
 pub mod numpy;
 pub mod stmt;
 

nac3core/src/codegen/model/any.rs

@@ -0,0 +1,41 @@
+use inkwell::{
+    context::Context,
+    types::{BasicType, BasicTypeEnum},
+    values::BasicValueEnum,
+};
+
+use super::*;
+use crate::codegen::CodeGenerator;
+
+/// A [`Model`] of any [`BasicTypeEnum`].
+///
+/// Use this when it is infeasible to use model abstractions.
+#[derive(Debug, Clone, Copy)]
+pub struct Any<'ctx>(pub BasicTypeEnum<'ctx>);
+
+impl<'ctx> Model<'ctx> for Any<'ctx> {
+    type Value = BasicValueEnum<'ctx>;
+    type Type = BasicTypeEnum<'ctx>;
+
+    fn llvm_type<G: CodeGenerator + ?Sized>(
+        &self,
+        _generator: &G,
+        _ctx: &'ctx Context,
+    ) -> Self::Type {
+        self.0
+    }
+
+    fn check_type<T: BasicType<'ctx>, G: CodeGenerator + ?Sized>(
+        &self,
+        _generator: &mut G,
+        _ctx: &'ctx Context,
+        ty: T,
+    ) -> Result<(), ModelError> {
+        let ty = ty.as_basic_type_enum();
+        if ty == self.0 {
+            Ok(())
+        } else {
+            Err(ModelError(format!("Expecting {}, but got {}", self.0, ty)))
+        }
+    }
+}

nac3core/src/codegen/model/array.rs

@@ -0,0 +1,146 @@
+use std::fmt;
+
+use inkwell::{
+    context::Context,
+    types::{ArrayType, BasicType, BasicTypeEnum},
+    values::{ArrayValue, IntValue},
+};
+
+use super::*;
+use crate::codegen::{CodeGenContext, CodeGenerator};
+
+/// Trait for Rust structs identifying length values for [`Array`].
+pub trait ArrayLen: fmt::Debug + Clone + Copy {
+    fn length(&self) -> u32;
+}
+
+/// A statically known length.
+#[derive(Debug, Clone, Copy, Default)]
+pub struct Len<const N: u32>;
+
+/// A dynamically known length.
+#[derive(Debug, Clone, Copy)]
+pub struct AnyLen(pub u32);
+
+impl<const N: u32> ArrayLen for Len<N> {
+    fn length(&self) -> u32 {
+        N
+    }
+}
+
+impl ArrayLen for AnyLen {
+    fn length(&self) -> u32 {
+        self.0
+    }
+}
+
+/// A Model for an [`ArrayType`].
+///
+/// `Len` should be of a [`LenKind`] and `Item` should be a of [`Model`].
+#[derive(Debug, Clone, Copy, Default)]
+pub struct Array<Len, Item> {
+    /// Length of this array.
+    pub len: Len,
+    /// [`Model`] of the array items.
+    pub item: Item,
+}
+
+impl<'ctx, Len: ArrayLen, Item: Model<'ctx>> Model<'ctx> for Array<Len, Item> {
+    type Value = ArrayValue<'ctx>;
+    type Type = ArrayType<'ctx>;
+
+    fn llvm_type<G: CodeGenerator + ?Sized>(
+        &self,
+        generator: &G,
+        ctx: &'ctx Context,
+    ) -> Self::Type {
+        self.item.llvm_type(generator, ctx).array_type(self.len.length())
+    }
+
+    fn check_type<T: BasicType<'ctx>, G: CodeGenerator + ?Sized>(
+        &self,
+        generator: &mut G,
+        ctx: &'ctx Context,
+        ty: T,
+    ) -> Result<(), ModelError> {
+        let ty = ty.as_basic_type_enum();
+        let BasicTypeEnum::ArrayType(ty) = ty else {
+            return Err(ModelError(format!("Expecting ArrayType, but got {ty:?}")));
+        };
+
+        if ty.len() != self.len.length() {
+            return Err(ModelError(format!(
+                "Expecting ArrayType with size {}, but got an ArrayType with size {}",
+                ty.len(),
+                self.len.length()
+            )));
+        }
+
+        self.item
+            .check_type(generator, ctx, ty.get_element_type())
+            .map_err(|err| err.under_context("an ArrayType"))?;
+
+        Ok(())
+    }
+}
+
+impl<'ctx, Len: ArrayLen, Item: Model<'ctx>> Instance<'ctx, Ptr<Array<Len, Item>>> {
+    /// Get the pointer to the `i`-th (0-based) array element.
+    pub fn gep(
+        &self,
+        ctx: &CodeGenContext<'ctx, '_>,
+        i: IntValue<'ctx>,
+    ) -> Instance<'ctx, Ptr<Item>> {
+        let zero = ctx.ctx.i32_type().const_zero();
+        let ptr = unsafe { ctx.builder.build_in_bounds_gep(self.value, &[zero, i], "").unwrap() };
+
+        unsafe { Ptr(self.model.0.item).believe_value(ptr) }
+    }
+
+    /// Like `gep` but `i` is a constant.
+    pub fn gep_const(&self, ctx: &CodeGenContext<'ctx, '_>, i: u64) -> Instance<'ctx, Ptr<Item>> {
+        assert!(
+            i < u64::from(self.model.0.len.length()),
+            "Index {i} is out of bounds. Array length = {}",
+            self.model.0.len.length()
+        );
+
+        let i = ctx.ctx.i32_type().const_int(i, false);
+        self.gep(ctx, i)
+    }
+
+    /// Convenience function equivalent to `.gep(...).load(...)`.
+    pub fn get<G: CodeGenerator + ?Sized>(
+        &self,
+        generator: &mut G,
+        ctx: &CodeGenContext<'ctx, '_>,
+        i: IntValue<'ctx>,
+    ) -> Instance<'ctx, Item> {
+        self.gep(ctx, i).load(generator, ctx)
+    }
+
+    /// Like `get` but `i` is a constant.
+    pub fn get_const<G: CodeGenerator + ?Sized>(
+        &self,
+        generator: &mut G,
+        ctx: &CodeGenContext<'ctx, '_>,
+        i: u64,
+    ) -> Instance<'ctx, Item> {
+        self.gep_const(ctx, i).load(generator, ctx)
+    }
+
+    /// Convenience function equivalent to `.gep(...).store(...)`.
+    pub fn set(
+        &self,
+        ctx: &CodeGenContext<'ctx, '_>,
+        i: IntValue<'ctx>,
+        value: Instance<'ctx, Item>,
+    ) {
+        self.gep(ctx, i).store(ctx, value);
+    }
+
+    /// Like `set` but `i` is a constant.
+    pub fn set_const(&self, ctx: &CodeGenContext<'ctx, '_>, i: u64, value: Instance<'ctx, Item>) {
+        self.gep_const(ctx, i).store(ctx, value);
+    }
+}

nac3core/src/codegen/model/core.rs

@@ -0,0 +1,207 @@
+use std::fmt;
+
+use inkwell::{context::Context, types::*, values::*};
+use itertools::Itertools;
+
+use super::*;
+use crate::codegen::{CodeGenContext, CodeGenerator};
+
+/// A error type for reporting any [`Model`]-related error (e.g., a [`BasicType`] mismatch).
+#[derive(Debug, Clone)]
+pub struct ModelError(pub String);
+
+impl ModelError {
+    /// Append a context message to the error.
+    pub(super) fn under_context(mut self, context: &str) -> Self {
+        self.0.push_str(" ... in ");
+        self.0.push_str(context);
+        self
+    }
+}
+
+/// Trait for Rust structs identifying [`BasicType`]s in the context of a known [`CodeGenerator`] and [`CodeGenContext`].
+///
+/// For instance,
+/// - [`Int<Int32>`] identifies an [`IntType`] with 32-bits.
+/// - [`Int<SizeT>`] identifies an [`IntType`] with bit-width [`CodeGenerator::get_size_type`].
+/// - [`Ptr<Int<SizeT>>`] identifies a [`PointerType`] that points to an [`IntType`] with bit-width [`CodeGenerator::get_size_type`].
+/// - [`Int<AnyInt>`] identifies an [`IntType`] with bit-width of whatever is set in the [`AnyInt`] object.
+/// - [`Any`] identifies a [`BasicType`] set in the [`Any`] object itself.
+///
+/// You can get the [`BasicType`] out of a model with [`Model::get_type`].
+///
+/// Furthermore, [`Instance<'ctx, M>`] is a simple structure that carries a [`BasicValue`] with [`BasicType`] identified by model `M`.
+///
+/// The main purpose of this abstraction is to have a more Rust type-safe way to use Inkwell and give type-hints for programmers.
+///
+/// ### Notes on `Default` trait
+///
+/// For some models like [`Int<Int32>`] or [`Int<SizeT>`], they have a [`Default`] trait since just by looking at their types, it is possible
+/// to tell the [`BasicType`]s they are identifying.
+///
+/// This can be used to create strongly-typed interfaces accepting only values of a specific [`BasicType`] without having to worry about
+/// writing debug assertions to check, for example, if the programmer has passed in an [`IntValue`] with the wrong bit-width.
+/// ```ignore
+/// fn give_me_i32_and_get_a_size_t_back<'ctx>(i32: Instance<'ctx, Int<Int32>>) -> Instance<'ctx, Int<SizeT>> {
+///     // code...
+/// }
+/// ```
+///
+/// ### Notes on converting between Inkwell and model/ge.
+///
+/// Suppose you have an [`IntValue`], and you want to pass it into a function that takes a [`Instance<'ctx, Int<Int32>>`]. You can do use
+/// [`Model::check_value`] or [`Model::believe_value`].
+/// ```ignore
+/// let my_value: IntValue<'ctx>;
+///
+/// let my_value = Int(Int32).check_value(my_value).unwrap(); // Panics if `my_value` is not 32-bit with a descriptive error message.
+///
+/// // or, if you are absolutely certain that `my_value` is 32-bit and doing extra checks is a waste of time:
+/// let my_value = Int(Int32).believe_value(my_value);
+/// ```
+pub trait Model<'ctx>: fmt::Debug + Clone + Copy {
+    /// The [`BasicType`] *variant* this model is identifying.
+    type Type: BasicType<'ctx>;
+
+    /// The [`BasicValue`] type of the [`BasicType`] of this model.
+    type Value: BasicValue<'ctx> + TryFrom<BasicValueEnum<'ctx>>;
+
+    /// Return the [`BasicType`] of this model.
+    #[must_use]
+    fn llvm_type<G: CodeGenerator + ?Sized>(&self, generator: &G, ctx: &'ctx Context)
+        -> Self::Type;
+
+    /// Get the number of bytes of the [`BasicType`] of this model.
+    fn size_of<G: CodeGenerator + ?Sized>(
+        &self,
+        generator: &mut G,
+        ctx: &'ctx Context,
+    ) -> IntValue<'ctx> {
+        self.llvm_type(generator, ctx).size_of().unwrap()
+    }
+
+    /// Check if a [`BasicType`] matches the [`BasicType`] of this model.
+    fn check_type<T: BasicType<'ctx>, G: CodeGenerator + ?Sized>(
+        &self,
+        generator: &mut G,
+        ctx: &'ctx Context,
+        ty: T,
+    ) -> Result<(), ModelError>;
+
+    /// Create an instance from a value.
+    ///
+    /// # Safety
+    ///
+    /// Caller must make sure the type of `value` and the type of this `model` are equivalent.
+    #[must_use]
+    unsafe fn believe_value(&self, value: Self::Value) -> Instance<'ctx, Self> {
+        Instance { model: *self, value }
+    }
+
+    /// Check if a [`BasicValue`]'s type is equivalent to the type of this model.
+    /// Wrap the [`BasicValue`] into an [`Instance`] if it is.
+    fn check_value<V: BasicValue<'ctx>, G: CodeGenerator + ?Sized>(
+        &self,
+        generator: &mut G,
+        ctx: &'ctx Context,
+        value: V,
+    ) -> Result<Instance<'ctx, Self>, ModelError> {
+        let value = value.as_basic_value_enum();
+        self.check_type(generator, ctx, value.get_type())
+            .map_err(|err| err.under_context(format!("the value {value:?}").as_str()))?;
+
+        let Ok(value) = Self::Value::try_from(value) else {
+            unreachable!("check_type() has bad implementation")
+        };
+        unsafe { Ok(self.believe_value(value)) }
+    }
+
+    // Allocate a value on the stack and return its pointer.
+    fn alloca<G: CodeGenerator + ?Sized>(
+        &self,
+        generator: &mut G,
+        ctx: &CodeGenContext<'ctx, '_>,
+    ) -> Instance<'ctx, Ptr<Self>> {
+        let p = ctx.builder.build_alloca(self.llvm_type(generator, ctx.ctx), "").unwrap();
+        unsafe { Ptr(*self).believe_value(p) }
+    }
+
+    // Allocate an array on the stack and return its pointer.
+    fn array_alloca<G: CodeGenerator + ?Sized>(
+        &self,
+        generator: &mut G,
+        ctx: &CodeGenContext<'ctx, '_>,
+        len: IntValue<'ctx>,
+    ) -> Instance<'ctx, Ptr<Self>> {
+        let p =
+            ctx.builder.build_array_alloca(self.llvm_type(generator, ctx.ctx), len, "").unwrap();
+        unsafe { Ptr(*self).believe_value(p) }
+    }
+
+    fn var_alloca<G: CodeGenerator + ?Sized>(
+        &self,
+        generator: &mut G,
+        ctx: &mut CodeGenContext<'ctx, '_>,
+        name: Option<&str>,
+    ) -> Result<Instance<'ctx, Ptr<Self>>, String> {
+        let ty = self.llvm_type(generator, ctx.ctx).as_basic_type_enum();
+        let p = generator.gen_var_alloc(ctx, ty, name)?;
+        unsafe { Ok(Ptr(*self).believe_value(p)) }
+    }
+
+    fn array_var_alloca<G: CodeGenerator + ?Sized>(
+        &self,
+        generator: &mut G,
+        ctx: &mut CodeGenContext<'ctx, '_>,
+        len: IntValue<'ctx>,
+        name: Option<&'ctx str>,
+    ) -> Result<Instance<'ctx, Ptr<Self>>, String> {
+        // TODO: Remove ArraySliceValue
+        let ty = self.llvm_type(generator, ctx.ctx).as_basic_type_enum();
+        let p = generator.gen_array_var_alloc(ctx, ty, len, name)?;
+        unsafe { Ok(Ptr(*self).believe_value(PointerValue::from(p))) }
+    }
+
+    /// Allocate a constant array.
+    fn const_array<G: CodeGenerator + ?Sized>(
+        &self,
+        generator: &mut G,
+        ctx: &'ctx Context,
+        values: &[Instance<'ctx, Self>],
+    ) -> Instance<'ctx, Array<AnyLen, Self>> {
+        macro_rules! make {
+            ($t:expr, $into_value:expr) => {
+                $t.const_array(
+                    &values
+                        .iter()
+                        .map(|x| $into_value(x.value.as_basic_value_enum()))
+                        .collect_vec(),
+                )
+            };
+        }
+
+        let value = match self.llvm_type(generator, ctx).as_basic_type_enum() {
+            BasicTypeEnum::ArrayType(t) => make!(t, BasicValueEnum::into_array_value),
+            BasicTypeEnum::IntType(t) => make!(t, BasicValueEnum::into_int_value),
+            BasicTypeEnum::FloatType(t) => make!(t, BasicValueEnum::into_float_value),
+            BasicTypeEnum::PointerType(t) => make!(t, BasicValueEnum::into_pointer_value),
+            BasicTypeEnum::StructType(t) => make!(t, BasicValueEnum::into_struct_value),
+            BasicTypeEnum::VectorType(t) => make!(t, BasicValueEnum::into_vector_value),
+        };
+
+        Array { len: AnyLen(values.len() as u32), item: *self }
+            .check_value(generator, ctx, value)
+            .unwrap()
+    }
+}
+
+#[derive(Debug, Clone, Copy)]
+pub struct Instance<'ctx, M: Model<'ctx>> {
+    /// The model of this instance.
+    pub model: M,
+
+    /// The value of this instance.
+    ///
+    /// It is guaranteed the [`BasicType`] of `value` is consistent with that of `model`.
+    pub value: M::Value,
+}

nac3core/src/codegen/model/float.rs

@@ -0,0 +1,93 @@
+use std::fmt;
+
+use inkwell::{
+    context::Context,
+    types::{BasicType, FloatType},
+    values::FloatValue,
+};
+
+use super::*;
+use crate::codegen::CodeGenerator;
+
+pub trait FloatKind<'ctx>: fmt::Debug + Clone + Copy {
+    fn get_float_type<G: CodeGenerator + ?Sized>(
+        &self,
+        generator: &G,
+        ctx: &'ctx Context,
+    ) -> FloatType<'ctx>;
+}
+
+#[derive(Debug, Clone, Copy, Default)]
+pub struct Float32;
+#[derive(Debug, Clone, Copy, Default)]
+pub struct Float64;
+
+impl<'ctx> FloatKind<'ctx> for Float32 {
+    fn get_float_type<G: CodeGenerator + ?Sized>(
+        &self,
+        _generator: &G,
+        ctx: &'ctx Context,
+    ) -> FloatType<'ctx> {
+        ctx.f32_type()
+    }
+}
+
+impl<'ctx> FloatKind<'ctx> for Float64 {
+    fn get_float_type<G: CodeGenerator + ?Sized>(
+        &self,
+        _generator: &G,
+        ctx: &'ctx Context,
+    ) -> FloatType<'ctx> {
+        ctx.f64_type()
+    }
+}
+
+#[derive(Debug, Clone, Copy)]
+pub struct AnyFloat<'ctx>(FloatType<'ctx>);
+
+impl<'ctx> FloatKind<'ctx> for AnyFloat<'ctx> {
+    fn get_float_type<G: CodeGenerator + ?Sized>(
+        &self,
+        _generator: &G,
+        _ctx: &'ctx Context,
+    ) -> FloatType<'ctx> {
+        self.0
+    }
+}
+
+#[derive(Debug, Clone, Copy, Default)]
+pub struct Float<N>(pub N);
+
+impl<'ctx, N: FloatKind<'ctx>> Model<'ctx> for Float<N> {
+    type Value = FloatValue<'ctx>;
+    type Type = FloatType<'ctx>;
+
+    fn llvm_type<G: CodeGenerator + ?Sized>(
+        &self,
+        generator: &G,
+        ctx: &'ctx Context,
+    ) -> Self::Type {
+        self.0.get_float_type(generator, ctx)
+    }
+
+    fn check_type<T: BasicType<'ctx>, G: CodeGenerator + ?Sized>(
+        &self,
+        generator: &mut G,
+        ctx: &'ctx Context,
+        ty: T,
+    ) -> Result<(), ModelError> {
+        let ty = ty.as_basic_type_enum();
+        let Ok(ty) = FloatType::try_from(ty) else {
+            return Err(ModelError(format!("Expecting FloatType, but got {ty:?}")));
+        };
+
+        let exp_ty = self.0.get_float_type(generator, ctx);
+
+        // TODO: Inkwell does not have get_bit_width for FloatType?
+        if ty != exp_ty {
+            return Err(ModelError(format!("Expecting {exp_ty:?}, but got {ty:?}")));
+        }
+
+        Ok(())
+    }
+}

nac3core/src/codegen/model/function.rs

@@ -0,0 +1,121 @@
+use inkwell::{
+    attributes::{Attribute, AttributeLoc},
+    types::{BasicMetadataTypeEnum, BasicType, FunctionType},
+    values::{AnyValue, BasicMetadataValueEnum, BasicValue, BasicValueEnum, CallSiteValue},
+};
+use itertools::Itertools;
+
+use super::*;
+use crate::codegen::{CodeGenContext, CodeGenerator};
+
+#[derive(Debug, Clone, Copy)]
+struct Arg<'ctx> {
+    ty: BasicMetadataTypeEnum<'ctx>,
+    val: BasicMetadataValueEnum<'ctx>,
+}
+
+/// A convenience structure to construct & call an LLVM function.
+///
+/// ### Usage
+///
+/// The syntax is like this:
+/// ```ignore
+/// let result = CallFunction::begin("my_function_name")
+///   .attrs(...)
+///   .arg(arg1)
+///   .arg(arg2)
+///   .arg(arg3)
+///   .returning("my_function_result", Int32);
+/// ```
+///
+/// The function `my_function_name` is called when `.returning()` (or its variants) is called, returning
+/// the result as an `Instance<'ctx, Int<Int32>>`.
+///
+/// If `my_function_name` has not been declared in `ctx.module`, once `.returning()` is called, a function
+/// declaration of `my_function_name` is added to `ctx.module`, where the [`FunctionType`] is deduced from
+/// the argument types and returning type.
+pub struct FnCall<'ctx, 'a, 'b, 'c, 'd, G: CodeGenerator + ?Sized> {
+    generator: &'d mut G,
+    ctx: &'b CodeGenContext<'ctx, 'a>,
+    /// Function name
+    name: &'c str,
+    /// Call arguments
+    args: Vec<Arg<'ctx>>,
+    /// LLVM function Attributes
+    attrs: Vec<&'static str>,
+}
+
+impl<'ctx, 'a, 'b, 'c, 'd, G: CodeGenerator + ?Sized> FnCall<'ctx, 'a, 'b, 'c, 'd, G> {
+    pub fn builder(generator: &'d mut G, ctx: &'b CodeGenContext<'ctx, 'a>, name: &'c str) -> Self {
+        FnCall { generator, ctx, name, args: Vec::new(), attrs: Vec::new() }
+    }
+
+    /// Push a list of LLVM function attributes to the function declaration.
+    #[must_use]
+    pub fn attrs(mut self, attrs: Vec<&'static str>) -> Self {
+        self.attrs = attrs;
+        self
+    }
+
+    /// Push a call argument to the function call.
+    #[allow(clippy::needless_pass_by_value)]
+    #[must_use]
+    pub fn arg<M: Model<'ctx>>(mut self, arg: Instance<'ctx, M>) -> Self {
+        let arg = Arg {
+            ty: arg.model.llvm_type(self.generator, self.ctx.ctx).as_basic_type_enum().into(),
+            val: arg.value.as_basic_value_enum().into(),
+        };
+        self.args.push(arg);
+        self
+    }
+
+    /// Call the function and expect the function to return a value of type of `return_model`.
+    #[must_use]
+    pub fn returning<M: Model<'ctx>>(self, name: &str, return_model: M) -> Instance<'ctx, M> {
+        let ret_ty = return_model.llvm_type(self.generator, self.ctx.ctx);
+
+        let ret = self.call(|tys| ret_ty.fn_type(tys, false), name);
+        let ret = BasicValueEnum::try_from(ret.as_any_value_enum()).unwrap(); // Must work
+        let ret = return_model.check_value(self.generator, self.ctx.ctx, ret).unwrap(); // Must work
+        ret
+    }
+
+    /// Like [`CallFunction::returning_`] but `return_model` is automatically inferred.
+    #[must_use]
+    pub fn returning_auto<M: Model<'ctx> + Default>(self, name: &str) -> Instance<'ctx, M> {
+        self.returning(name, M::default())
+    }
+
+    /// Call the function and expect the function to return a void-type.
+    pub fn returning_void(self) {
+        let ret_ty = self.ctx.ctx.void_type();
+
+        let _ = self.call(|tys| ret_ty.fn_type(tys, false), "");
+    }
+
+    fn call<F>(&self, make_fn_type: F, return_value_name: &str) -> CallSiteValue<'ctx>
+    where
+        F: FnOnce(&[BasicMetadataTypeEnum<'ctx>]) -> FunctionType<'ctx>,
+    {
+        // Get the LLVM function.
+        let func = self.ctx.module.get_function(self.name).unwrap_or_else(|| {
+            // Declare the function if it doesn't exist.
+            let tys = self.args.iter().map(|arg| arg.ty).collect_vec();
+
+            let func_type = make_fn_type(&tys);
+            let func = self.ctx.module.add_function(self.name, func_type, None);
+
+            for attr in &self.attrs {
+                func.add_attribute(
+                    AttributeLoc::Function,
+                    self.ctx.ctx.create_enum_attribute(Attribute::get_named_enum_kind_id(attr), 0),
+                );
+            }
+
+            func
+        });
+
+        let vals = self.args.iter().map(|arg| arg.val).collect_vec();
+        self.ctx.builder.build_call(func, &vals, return_value_name).unwrap()
+    }
+}

nac3core/src/codegen/model/int.rs

@@ -0,0 +1,421 @@
+use std::{cmp::Ordering, fmt};
+
+use inkwell::{
+    context::Context,
+    types::{BasicType, IntType},
+    values::IntValue,
+    IntPredicate,
+};
+
+use super::*;
+use crate::codegen::{CodeGenContext, CodeGenerator};
+
+pub trait IntKind<'ctx>: fmt::Debug + Clone + Copy {
+    fn get_int_type<G: CodeGenerator + ?Sized>(
+        &self,
+        generator: &G,
+        ctx: &'ctx Context,
+    ) -> IntType<'ctx>;
+}
+
+#[derive(Debug, Clone, Copy, Default)]
+pub struct Bool;
+#[derive(Debug, Clone, Copy, Default)]
+pub struct Byte;
+#[derive(Debug, Clone, Copy, Default)]
+pub struct Int32;
+#[derive(Debug, Clone, Copy, Default)]
+pub struct Int64;
+#[derive(Debug, Clone, Copy, Default)]
+pub struct SizeT;
+
+impl<'ctx> IntKind<'ctx> for Bool {
+    fn get_int_type<G: CodeGenerator + ?Sized>(
+        &self,
+        _generator: &G,
+        ctx: &'ctx Context,
+    ) -> IntType<'ctx> {
+        ctx.bool_type()
+    }
+}
+
+impl<'ctx> IntKind<'ctx> for Byte {
+    fn get_int_type<G: CodeGenerator + ?Sized>(
+        &self,
+        _generator: &G,
+        ctx: &'ctx Context,
+    ) -> IntType<'ctx> {
+        ctx.i8_type()
+    }
+}
+
+impl<'ctx> IntKind<'ctx> for Int32 {
+    fn get_int_type<G: CodeGenerator + ?Sized>(
+        &self,
+        _generator: &G,
+        ctx: &'ctx Context,
+    ) -> IntType<'ctx> {
+        ctx.i32_type()
+    }
+}
+
+impl<'ctx> IntKind<'ctx> for Int64 {
+    fn get_int_type<G: CodeGenerator + ?Sized>(
+        &self,
+        _generator: &G,
+        ctx: &'ctx Context,
+    ) -> IntType<'ctx> {
+        ctx.i64_type()
+    }
+}
+
+impl<'ctx> IntKind<'ctx> for SizeT {
+    fn get_int_type<G: CodeGenerator + ?Sized>(
+        &self,
+        generator: &G,
+        ctx: &'ctx Context,
+    ) -> IntType<'ctx> {
+        generator.get_size_type(ctx)
+    }
+}
+
+#[derive(Debug, Clone, Copy)]
+pub struct AnyInt<'ctx>(pub IntType<'ctx>);
+
+impl<'ctx> IntKind<'ctx> for AnyInt<'ctx> {
+    fn get_int_type<G: CodeGenerator + ?Sized>(
+        &self,
+        _generator: &G,
+        _ctx: &'ctx Context,
+    ) -> IntType<'ctx> {
+        self.0
+    }
+}
+
+#[derive(Debug, Clone, Copy, Default)]
+pub struct Int<N>(pub N);
+
+impl<'ctx, N: IntKind<'ctx>> Model<'ctx> for Int<N> {
+    type Value = IntValue<'ctx>;
+    type Type = IntType<'ctx>;
+
+    fn llvm_type<G: CodeGenerator + ?Sized>(
+        &self,
+        generator: &G,
+        ctx: &'ctx Context,
+    ) -> Self::Type {
+        self.0.get_int_type(generator, ctx)
+    }
+
+    fn check_type<T: BasicType<'ctx>, G: CodeGenerator + ?Sized>(
+        &self,
+        generator: &mut G,
+        ctx: &'ctx Context,
+        ty: T,
+    ) -> Result<(), ModelError> {
+        let ty = ty.as_basic_type_enum();
+        let Ok(ty) = IntType::try_from(ty) else {
+            return Err(ModelError(format!("Expecting IntType, but got {ty:?}")));
+        };
+
+        let exp_ty = self.0.get_int_type(generator, ctx);
+        if ty.get_bit_width() != exp_ty.get_bit_width() {
+            return Err(ModelError(format!(
+                "Expecting IntType to have {} bit(s), but got {} bit(s)",
+                exp_ty.get_bit_width(),
+                ty.get_bit_width()
+            )));
+        }
+
+        Ok(())
+    }
+}
+
+impl<'ctx, N: IntKind<'ctx>> Int<N> {
+    pub fn const_int<G: CodeGenerator + ?Sized>(
+        &self,
+        generator: &mut G,
+        ctx: &'ctx Context,
+        value: u64,
+        sign_extend: bool,
+    ) -> Instance<'ctx, Self> {
+        let value = self.llvm_type(generator, ctx).const_int(value, sign_extend);
+        unsafe { self.believe_value(value) }
+    }
+
+    pub fn const_0<G: CodeGenerator + ?Sized>(
+        &self,
+        generator: &mut G,
+        ctx: &'ctx Context,
+    ) -> Instance<'ctx, Self> {
+        let value = self.llvm_type(generator, ctx).const_zero();
+        unsafe { self.believe_value(value) }
+    }
+
+    pub fn const_1<G: CodeGenerator + ?Sized>(
+        &self,
+        generator: &mut G,
+        ctx: &'ctx Context,
+    ) -> Instance<'ctx, Self> {
+        self.const_int(generator, ctx, 1, false)
+    }
+
+    pub fn const_all_ones<G: CodeGenerator + ?Sized>(
+        &self,
+        generator: &mut G,
+        ctx: &'ctx Context,
+    ) -> Instance<'ctx, Self> {
+        let value = self.llvm_type(generator, ctx).const_all_ones();
+        unsafe { self.believe_value(value) }
+    }
+
+    pub fn s_extend_or_bit_cast<G: CodeGenerator + ?Sized>(
+        &self,
+        generator: &mut G,
+        ctx: &CodeGenContext<'ctx, '_>,
+        value: IntValue<'ctx>,
+    ) -> Instance<'ctx, Self> {
+        assert!(
+            value.get_type().get_bit_width()
+                <= self.0.get_int_type(generator, ctx.ctx).get_bit_width()
+        );
+        let value = ctx
+            .builder
+            .build_int_s_extend_or_bit_cast(value, self.llvm_type(generator, ctx.ctx), "")
+            .unwrap();
+        unsafe { self.believe_value(value) }
+    }
+
+    pub fn s_extend<G: CodeGenerator + ?Sized>(
+        &self,
+        generator: &mut G,
+        ctx: &CodeGenContext<'ctx, '_>,
+        value: IntValue<'ctx>,
+    ) -> Instance<'ctx, Self> {
+        assert!(
+            value.get_type().get_bit_width()
+                < self.0.get_int_type(generator, ctx.ctx).get_bit_width()
+        );
+        let value =
+            ctx.builder.build_int_s_extend(value, self.llvm_type(generator, ctx.ctx), "").unwrap();
+        unsafe { self.believe_value(value) }
+    }
+
+    pub fn z_extend_or_bit_cast<G: CodeGenerator + ?Sized>(
+        &self,
+        generator: &mut G,
+        ctx: &CodeGenContext<'ctx, '_>,
+        value: IntValue<'ctx>,
+    ) -> Instance<'ctx, Self> {
+        assert!(
+            value.get_type().get_bit_width()
+                <= self.0.get_int_type(generator, ctx.ctx).get_bit_width()
+        );
+        let value = ctx
+            .builder
+            .build_int_z_extend_or_bit_cast(value, self.llvm_type(generator, ctx.ctx), "")
+            .unwrap();
+        unsafe { self.believe_value(value) }
+    }
+
+    pub fn z_extend<G: CodeGenerator + ?Sized>(
+        &self,
+        generator: &mut G,
+        ctx: &CodeGenContext<'ctx, '_>,
+        value: IntValue<'ctx>,
+    ) -> Instance<'ctx, Self> {
+        assert!(
+            value.get_type().get_bit_width()
+                < self.0.get_int_type(generator, ctx.ctx).get_bit_width()
+        );
+        let value =
+            ctx.builder.build_int_z_extend(value, self.llvm_type(generator, ctx.ctx), "").unwrap();
+        unsafe { self.believe_value(value) }
+    }
+
+    pub fn truncate_or_bit_cast<G: CodeGenerator + ?Sized>(
+        &self,
+        generator: &mut G,
+        ctx: &CodeGenContext<'ctx, '_>,
+        value: IntValue<'ctx>,
+    ) -> Instance<'ctx, Self> {
+        assert!(
+            value.get_type().get_bit_width()
+                >= self.0.get_int_type(generator, ctx.ctx).get_bit_width()
+        );
+        let value = ctx
+            .builder
+            .build_int_truncate_or_bit_cast(value, self.llvm_type(generator, ctx.ctx), "")
+            .unwrap();
+        unsafe { self.believe_value(value) }
+    }
+
+    pub fn truncate<G: CodeGenerator + ?Sized>(
+        &self,
+        generator: &mut G,
+        ctx: &CodeGenContext<'ctx, '_>,
+        value: IntValue<'ctx>,
+    ) -> Instance<'ctx, Self> {
+        assert!(
+            value.get_type().get_bit_width()
+                > self.0.get_int_type(generator, ctx.ctx).get_bit_width()
+        );
+        let value =
+            ctx.builder.build_int_truncate(value, self.llvm_type(generator, ctx.ctx), "").unwrap();
+        unsafe { self.believe_value(value) }
+    }
+
+    /// `sext` or `trunc` an int to this model's int type. Does nothing if equal bit-widths.
+    pub fn s_extend_or_truncate<G: CodeGenerator + ?Sized>(
+        &self,
+        generator: &mut G,
+        ctx: &CodeGenContext<'ctx, '_>,
+        value: IntValue<'ctx>,
+    ) -> Instance<'ctx, Self> {
+        let their_width = value.get_type().get_bit_width();
+        let our_width = self.0.get_int_type(generator, ctx.ctx).get_bit_width();
+        match their_width.cmp(&our_width) {
+            Ordering::Less => self.s_extend(generator, ctx, value),
+            Ordering::Equal => unsafe { self.believe_value(value) },
+            Ordering::Greater => self.truncate(generator, ctx, value),
+        }
+    }
+
+    /// `zext` or `trunc` an int to this model's int type. Does nothing if equal bit-widths.
+    pub fn z_extend_or_truncate<G: CodeGenerator + ?Sized>(
+        &self,
+        generator: &mut G,
+        ctx: &CodeGenContext<'ctx, '_>,
+        value: IntValue<'ctx>,
+    ) -> Instance<'ctx, Self> {
+        let their_width = value.get_type().get_bit_width();
+        let our_width = self.0.get_int_type(generator, ctx.ctx).get_bit_width();
+        match their_width.cmp(&our_width) {
+            Ordering::Less => self.z_extend(generator, ctx, value),
+            Ordering::Equal => unsafe { self.believe_value(value) },
+            Ordering::Greater => self.truncate(generator, ctx, value),
+        }
+    }
+}
+
+impl Int<Bool> {
+    #[must_use]
+    pub fn const_false<'ctx, G: CodeGenerator + ?Sized>(
+        &self,
+        generator: &mut G,
+        ctx: &'ctx Context,
+    ) -> Instance<'ctx, Self> {
+        self.const_int(generator, ctx, 0, false)
+    }
+
+    #[must_use]
+    pub fn const_true<'ctx, G: CodeGenerator + ?Sized>(
+        &self,
+        generator: &mut G,
+        ctx: &'ctx Context,
+    ) -> Instance<'ctx, Self> {
+        self.const_int(generator, ctx, 1, false)
+    }
+}
+
+impl<'ctx, N: IntKind<'ctx>> Instance<'ctx, Int<N>> {
+    pub fn s_extend_or_bit_cast<NewN: IntKind<'ctx>, G: CodeGenerator + ?Sized>(
+        &self,
+        generator: &mut G,
+        ctx: &CodeGenContext<'ctx, '_>,
+        to_int_kind: NewN,
+    ) -> Instance<'ctx, Int<NewN>> {
+        Int(to_int_kind).s_extend_or_bit_cast(generator, ctx, self.value)
+    }
+
+    pub fn s_extend<NewN: IntKind<'ctx>, G: CodeGenerator + ?Sized>(
+        &self,
+        generator: &mut G,
+        ctx: &CodeGenContext<'ctx, '_>,
+        to_int_kind: NewN,
+    ) -> Instance<'ctx, Int<NewN>> {
+        Int(to_int_kind).s_extend(generator, ctx, self.value)
+    }
+
+    pub fn z_extend_or_bit_cast<NewN: IntKind<'ctx>, G: CodeGenerator + ?Sized>(
+        &self,
+        generator: &mut G,
+        ctx: &CodeGenContext<'ctx, '_>,
+        to_int_kind: NewN,
+    ) -> Instance<'ctx, Int<NewN>> {
+        Int(to_int_kind).z_extend_or_bit_cast(generator, ctx, self.value)
+    }
+
+    pub fn z_extend<NewN: IntKind<'ctx>, G: CodeGenerator + ?Sized>(
+        &self,
+        generator: &mut G,
+        ctx: &CodeGenContext<'ctx, '_>,
+        to_int_kind: NewN,
+    ) -> Instance<'ctx, Int<NewN>> {
+        Int(to_int_kind).z_extend(generator, ctx, self.value)
+    }
+
+    pub fn truncate_or_bit_cast<NewN: IntKind<'ctx>, G: CodeGenerator + ?Sized>(
+        &self,
+        generator: &mut G,
+        ctx: &CodeGenContext<'ctx, '_>,
+        to_int_kind: NewN,
+    ) -> Instance<'ctx, Int<NewN>> {
+        Int(to_int_kind).truncate_or_bit_cast(generator, ctx, self.value)
+    }
+
+    pub fn truncate<NewN: IntKind<'ctx>, G: CodeGenerator + ?Sized>(
+        &self,
+        generator: &mut G,
+        ctx: &CodeGenContext<'ctx, '_>,
+        to_int_kind: NewN,
+    ) -> Instance<'ctx, Int<NewN>> {
+        Int(to_int_kind).truncate(generator, ctx, self.value)
+    }
+
+    pub fn s_extend_or_truncate<NewN: IntKind<'ctx>, G: CodeGenerator + ?Sized>(
+        &self,
+        generator: &mut G,
+        ctx: &CodeGenContext<'ctx, '_>,
+        to_int_kind: NewN,
+    ) -> Instance<'ctx, Int<NewN>> {
+        Int(to_int_kind).s_extend_or_truncate(generator, ctx, self.value)
+    }
+
+    pub fn z_extend_or_truncate<NewN: IntKind<'ctx>, G: CodeGenerator + ?Sized>(
+        &self,
+        generator: &mut G,
+        ctx: &CodeGenContext<'ctx, '_>,
+        to_int_kind: NewN,
+    ) -> Instance<'ctx, Int<NewN>> {
+        Int(to_int_kind).z_extend_or_truncate(generator, ctx, self.value)
+    }
+
+    #[must_use]
+    pub fn add(&self, ctx: &CodeGenContext<'ctx, '_>, other: Self) -> Self {
+        let value = ctx.builder.build_int_add(self.value, other.value, "").unwrap();
+        unsafe { self.model.believe_value(value) }
+    }
+
+    #[must_use]
+    pub fn sub(&self, ctx: &CodeGenContext<'ctx, '_>, other: Self) -> Self {
+        let value = ctx.builder.build_int_sub(self.value, other.value, "").unwrap();
+        unsafe { self.model.believe_value(value) }
+    }
+
+    #[must_use]
+    pub fn mul(&self, ctx: &CodeGenContext<'ctx, '_>, other: Self) -> Self {
+        let value = ctx.builder.build_int_mul(self.value, other.value, "").unwrap();
+        unsafe { self.model.believe_value(value) }
+    }
+
+    pub fn compare(
+        &self,
+        ctx: &CodeGenContext<'ctx, '_>,
+        op: IntPredicate,
+        other: Self,
+    ) -> Instance<'ctx, Int<Bool>> {
+        let value = ctx.builder.build_int_compare(op, self.value, other.value, "").unwrap();
+        unsafe { Int(Bool).believe_value(value) }
+    }
+}

nac3core/src/codegen/model/mod.rs

@@ -0,0 +1,16 @@
+mod any;
+mod array;
+mod core;
+mod float;
+pub mod function;
+mod int;
+mod ptr;
+mod structure;
+
+pub use any::*;
+pub use array::*;
+pub use core::*;
+pub use float::*;
+pub use int::*;
+pub use ptr::*;
+pub use structure::*;

nac3core/src/codegen/model/ptr.rs

@@ -0,0 +1,213 @@
+use inkwell::{
+    context::Context,
+    types::{BasicType, BasicTypeEnum, PointerType},
+    values::{IntValue, PointerValue},
+    AddressSpace,
+};
+
+use super::*;
+use crate::codegen::{llvm_intrinsics::call_memcpy_generic, CodeGenContext, CodeGenerator};
+
+/// A model for [`PointerType`].
+///
+/// `Item` is the element type this pointer is pointing to, and should be of a [`Model`].
+///
+// TODO: LLVM 15: `Item` is a Rust type-hint for the LLVM type of value the `.store()/.load()` family
+// of functions return. If a truly opaque pointer is needed, tell the programmer to use `OpaquePtr`.
+#[derive(Debug, Clone, Copy, Default)]
+pub struct Ptr<Item>(pub Item);
+
+/// An opaque pointer. Like [`Ptr`] but without any Rust type-hints about its element type.
+///
+/// `.load()/.store()` is not available for [`Instance`]s of opaque pointers.
+pub type OpaquePtr = Ptr<()>;
+
+// TODO: LLVM 15: `Item: Model<'ctx>` don't even need to be a model anymore. It will only be
+// a type-hint for the `.load()/.store()` functions for the `pointee_ty`.
+//
+// See https://thedan64.github.io/inkwell/inkwell/builder/struct.Builder.html#method.build_load.
+impl<'ctx, Item: Model<'ctx>> Model<'ctx> for Ptr<Item> {
+    type Value = PointerValue<'ctx>;
+    type Type = PointerType<'ctx>;
+
+    fn llvm_type<G: CodeGenerator + ?Sized>(
+        &self,
+        generator: &G,
+        ctx: &'ctx Context,
+    ) -> Self::Type {
+        // TODO: LLVM 15: ctx.ptr_type(AddressSpace::default())
+        self.0.llvm_type(generator, ctx).ptr_type(AddressSpace::default())
+    }
+
+    fn check_type<T: BasicType<'ctx>, G: CodeGenerator + ?Sized>(
+        &self,
+        generator: &mut G,
+        ctx: &'ctx Context,
+        ty: T,
+    ) -> Result<(), ModelError> {
+        let ty = ty.as_basic_type_enum();
+        let Ok(ty) = PointerType::try_from(ty) else {
+            return Err(ModelError(format!("Expecting PointerType, but got {ty:?}")));
+        };
+
+        let elem_ty = ty.get_element_type();
+        let Ok(elem_ty) = BasicTypeEnum::try_from(elem_ty) else {
+            return Err(ModelError(format!(
+                "Expecting pointer element type to be a BasicTypeEnum, but got {elem_ty:?}"
+            )));
+        };
+
+        // TODO: inkwell `get_element_type()` will be deprecated.
+        // Remove the check for `get_element_type()` when the time comes.
+        self.0
+            .check_type(generator, ctx, elem_ty)
+            .map_err(|err| err.under_context("a PointerType"))?;
+
+        Ok(())
+    }
+}
+
+impl<'ctx, Item: Model<'ctx>> Ptr<Item> {
+    /// Return a ***constant*** nullptr.
+    pub fn nullptr<G: CodeGenerator + ?Sized>(
+        &self,
+        generator: &mut G,
+        ctx: &'ctx Context,
+    ) -> Instance<'ctx, Ptr<Item>> {
+        let ptr = self.llvm_type(generator, ctx).const_null();
+        unsafe { self.believe_value(ptr) }
+    }
+
+    /// Cast a pointer into this model with [`inkwell::builder::Builder::build_pointer_cast`]
+    pub fn pointer_cast<G: CodeGenerator + ?Sized>(
+        &self,
+        generator: &mut G,
+        ctx: &CodeGenContext<'ctx, '_>,
+        ptr: PointerValue<'ctx>,
+    ) -> Instance<'ctx, Ptr<Item>> {
+        // TODO: LLVM 15: Write in an impl where `Item` does not have to be `Model<'ctx>`.
+        // TODO: LLVM 15: This function will only have to be:
+        // ```
+        // return self.believe_value(ptr);
+        // ```
+        let t = self.llvm_type(generator, ctx.ctx);
+        let ptr = ctx.builder.build_pointer_cast(ptr, t, "").unwrap();
+        unsafe { self.believe_value(ptr) }
+    }
+}
+
+impl<'ctx, Item: Model<'ctx>> Instance<'ctx, Ptr<Item>> {
+    /// Offset the pointer by [`inkwell::builder::Builder::build_in_bounds_gep`].
+    #[must_use]
+    pub fn offset(
+        &self,
+        ctx: &CodeGenContext<'ctx, '_>,
+        offset: IntValue<'ctx>,
+    ) -> Instance<'ctx, Ptr<Item>> {
+        let p = unsafe { ctx.builder.build_in_bounds_gep(self.value, &[offset], "").unwrap() };
+        unsafe { self.model.believe_value(p) }
+    }
+
+    /// Offset the pointer by [`inkwell::builder::Builder::build_in_bounds_gep`] by a constant offset.
+    #[must_use]
+    pub fn offset_const(
+        &self,
+        ctx: &CodeGenContext<'ctx, '_>,
+        offset: i64,
+    ) -> Instance<'ctx, Ptr<Item>> {
+        let offset = ctx.ctx.i32_type().const_int(offset as u64, true);
+        self.offset(ctx, offset)
+    }
+
+    pub fn set_index(
+        &self,
+        ctx: &CodeGenContext<'ctx, '_>,
+        index: IntValue<'ctx>,
+        value: Instance<'ctx, Item>,
+    ) {
+        self.offset(ctx, index).store(ctx, value);
+    }
+
+    pub fn set_index_const(
+        &self,
+        ctx: &CodeGenContext<'ctx, '_>,
+        index: i64,
+        value: Instance<'ctx, Item>,
+    ) {
+        self.offset_const(ctx, index).store(ctx, value);
+    }
+
+    pub fn get_index<G: CodeGenerator + ?Sized>(
+        &self,
+        generator: &mut G,
+        ctx: &CodeGenContext<'ctx, '_>,
+        index: IntValue<'ctx>,
+    ) -> Instance<'ctx, Item> {
+        self.offset(ctx, index).load(generator, ctx)
+    }
+
+    pub fn get_index_const<G: CodeGenerator + ?Sized>(
+        &self,
+        generator: &mut G,
+        ctx: &CodeGenContext<'ctx, '_>,
+        index: i64,
+    ) -> Instance<'ctx, Item> {
+        self.offset_const(ctx, index).load(generator, ctx)
+    }
+
+    /// Load the value with [`inkwell::builder::Builder::build_load`].
+    pub fn load<G: CodeGenerator + ?Sized>(
+        &self,
+        generator: &mut G,
+        ctx: &CodeGenContext<'ctx, '_>,
+    ) -> Instance<'ctx, Item> {
+        let value = ctx.builder.build_load(self.value, "").unwrap();
+        self.model.0.check_value(generator, ctx.ctx, value).unwrap() // If unwrap() panics, there is a logic error.
+    }
+
+    /// Store a value with [`inkwell::builder::Builder::build_store`].
+    pub fn store(&self, ctx: &CodeGenContext<'ctx, '_>, value: Instance<'ctx, Item>) {
+        ctx.builder.build_store(self.value, value.value).unwrap();
+    }
+
+    /// Return a casted pointer of element type `NewElement` with [`inkwell::builder::Builder::build_pointer_cast`].
+    pub fn pointer_cast<NewItem: Model<'ctx>, G: CodeGenerator + ?Sized>(
+        &self,
+        generator: &mut G,
+        ctx: &CodeGenContext<'ctx, '_>,
+        new_item: NewItem,
+    ) -> Instance<'ctx, Ptr<NewItem>> {
+        // TODO: LLVM 15: Write in an impl where `Item` does not have to be `Model<'ctx>`.
+        Ptr(new_item).pointer_cast(generator, ctx, self.value)
+    }
+
+    /// Check if the pointer is null with [`inkwell::builder::Builder::build_is_null`].
+    pub fn is_null(&self, ctx: &CodeGenContext<'ctx, '_>) -> Instance<'ctx, Int<Bool>> {
+        let value = ctx.builder.build_is_null(self.value, "").unwrap();
+        unsafe { Int(Bool).believe_value(value) }
+    }
+
+    /// Check if the pointer is not null with [`inkwell::builder::Builder::build_is_not_null`].
+    pub fn is_not_null(&self, ctx: &CodeGenContext<'ctx, '_>) -> Instance<'ctx, Int<Bool>> {
+        let value = ctx.builder.build_is_not_null(self.value, "").unwrap();
+        unsafe { Int(Bool).believe_value(value) }
+    }
+
+    /// `memcpy` from another pointer.
+    pub fn copy_from<G: CodeGenerator + ?Sized>(
+        &self,
+        generator: &mut G,
+        ctx: &CodeGenContext<'ctx, '_>,
+        source: Self,
+        num_items: IntValue<'ctx>,
+    ) {
+        // Force extend `num_items` and `itemsize` to `i64` so their types would match.
+        let itemsize = self.model.size_of(generator, ctx.ctx);
+        let itemsize = Int(SizeT).z_extend_or_truncate(generator, ctx, itemsize);
+        let num_items = Int(SizeT).z_extend_or_truncate(generator, ctx, num_items);
+        let totalsize = itemsize.mul(ctx, num_items);
+
+        let is_volatile = ctx.ctx.bool_type().const_zero(); // is_volatile = false
+        call_memcpy_generic(ctx, self.value, source.value, totalsize.value, is_volatile);
+    }
+}

nac3core/src/codegen/model/structure.rs

@@ -0,0 +1,363 @@
+use std::fmt;
+
+use inkwell::{
+    context::Context,
+    types::{BasicType, BasicTypeEnum, StructType},
+    values::{BasicValueEnum, StructValue},
+};
+
+use super::*;
+use crate::codegen::{CodeGenContext, CodeGenerator};
+
+/// A traveral that traverses a Rust `struct` that is used to declare an LLVM's struct's field types.
+pub trait FieldTraversal<'ctx> {
+    /// Output type of [`FieldTraversal::add`].
+    type Output<M>;
+
+    /// Traverse through the type of a declared field and do something with it.
+    ///
+    /// * `name` - The cosmetic name of the LLVM field. Used for debugging.
+    /// * `model` - The [`Model`] representing the LLVM type of this field.
+    fn add<M: Model<'ctx>>(&mut self, name: &'static str, model: M) -> Self::Output<M>;
+
+    /// Like [`FieldTraversal::add`] but [`Model`] is automatically inferred from its [`Default`] trait.
+    fn add_auto<M: Model<'ctx> + Default>(&mut self, name: &'static str) -> Self::Output<M> {
+        self.add(name, M::default())
+    }
+}
+
+/// Descriptor of an LLVM struct field.
+#[derive(Debug, Clone, Copy)]
+pub struct GepField<M> {
+    /// The GEP index of this field. This is the index to use with `build_gep`.
+    pub gep_index: u32,
+    /// The cosmetic name of this field.
+    pub name: &'static str,
+    /// The [`Model`] of this field's type.
+    pub model: M,
+}
+
+/// A traversal to calculate the GEP index of fields.
+pub struct GepFieldTraversal {
+    /// The current GEP index.
+    gep_index_counter: u32,
+}
+
+impl<'ctx> FieldTraversal<'ctx> for GepFieldTraversal {
+    type Output<M> = GepField<M>;
+
+    fn add<M: Model<'ctx>>(&mut self, name: &'static str, model: M) -> Self::Output<M> {
+        let gep_index = self.gep_index_counter;
+        self.gep_index_counter += 1;
+        Self::Output { gep_index, name, model }
+    }
+}
+
+/// A traversal to collect the field types of a struct.
+///
+/// This is used to collect field types and construct the LLVM struct type with [`Context::struct_type`].
+struct TypeFieldTraversal<'ctx, 'a, G: CodeGenerator + ?Sized> {
+    generator: &'a G,
+    ctx: &'ctx Context,
+    /// The collected field types so far in exact order.
+    field_types: Vec<BasicTypeEnum<'ctx>>,
+}
+
+impl<'ctx, 'a, G: CodeGenerator + ?Sized> FieldTraversal<'ctx> for TypeFieldTraversal<'ctx, 'a, G> {
+    type Output<M> = (); // Checking types return nothing.
+
+    fn add<M: Model<'ctx>>(&mut self, _name: &'static str, model: M) -> Self::Output<M> {
+        let t = model.llvm_type(self.generator, self.ctx).as_basic_type_enum();
+        self.field_types.push(t);
+    }
+}
+
+/// A traversal to check the types of fields.
+struct CheckTypeFieldTraversal<'ctx, 'a, G: CodeGenerator + ?Sized> {
+    generator: &'a mut G,
+    ctx: &'ctx Context,
+    /// The current GEP index, so we can tell the index of the field we are checking
+    /// and report the GEP index.
+    gep_index_counter: u32,
+    /// The [`StructType`] to check.
+    scrutinee: StructType<'ctx>,
+    /// The list of collected errors so far.
+    errors: Vec<ModelError>,
+}
+
+impl<'ctx, 'a, G: CodeGenerator + ?Sized> FieldTraversal<'ctx>
+    for CheckTypeFieldTraversal<'ctx, 'a, G>
+{
+    type Output<M> = (); // Checking types return nothing.
+
+    fn add<M: Model<'ctx>>(&mut self, name: &'static str, model: M) -> Self::Output<M> {
+        let gep_index = self.gep_index_counter;
+        self.gep_index_counter += 1;
+
+        if let Some(t) = self.scrutinee.get_field_type_at_index(gep_index) {
+            if let Err(err) = model.check_type(self.generator, self.ctx, t) {
+                self.errors
+                    .push(err.under_context(format!("field #{gep_index} '{name}'").as_str()));
+            }
+        }
+        // Otherwise, it will be caught by Struct's `check_type`.
+    }
+}
+
+/// A trait for Rust structs identifying LLVM structures.
+///
+/// ### Example
+///
+/// Suppose you want to define this structure:
+/// ```c
+/// template <typename T>
+/// struct ContiguousNDArray {
+///     size_t ndims;
+///     size_t* shape;
+///     T* data;
+/// }
+/// ```
+///
+/// This is how it should be done:
+/// ```ignore
+/// pub struct ContiguousNDArrayFields<'ctx, F: FieldTraversal<'ctx>, Item: Model<'ctx>> {
+///     pub ndims: F::Out<Int<SizeT>>,
+///     pub shape: F::Out<Ptr<Int<SizeT>>>,
+///     pub data: F::Out<Ptr<Item>>,
+/// }
+///
+/// /// An ndarray without strides and non-opaque `data` field in NAC3.
+/// #[derive(Debug, Clone, Copy)]
+/// pub struct ContiguousNDArray<M> {
+///     /// [`Model`] of the items.
+///     pub item: M,
+/// }
+///
+/// impl<'ctx, Item: Model<'ctx>> StructKind<'ctx> for ContiguousNDArray<Item> {
+///     type Fields<F: FieldTraversal<'ctx>> = ContiguousNDArrayFields<'ctx, F, Item>;
+///
+///     fn traverse_fields<F: FieldTraversal<'ctx>>(&self, traversal: &mut F) -> Self::Fields<F> {
+///         // The order of `traversal.add*` is important
+///         Self::Fields {
+///             ndims: traversal.add_auto("ndims"),
+///             shape: traversal.add_auto("shape"),
+///             data: traversal.add("data", Ptr(self.item)),
+///         }
+///     }
+/// }
+/// ```
+///
+/// The [`FieldTraversal`] here is a mechanism to allow the fields of `ContiguousNDArrayFields` to be
+/// traversed to do useful work such as:
+///
+/// - To create the [`StructType`] of `ContiguousNDArray` by collecting [`BasicType`]s of the fields.
+/// - To enable the `.gep(ctx, |f| f.ndims).store(ctx, ...)` syntax.
+///
+/// Suppose now that you have defined `ContiguousNDArray` and you want to allocate a `ContiguousNDArray`
+/// with dtype `float64` in LLVM, this is how you do it:
+/// ```ignore
+/// type F64NDArray = Struct<ContiguousNDArray<Float<Float64>>>; // Type alias for leaner documentation
+/// let model: F64NDArray = Struct(ContigousNDArray { item: Float(Float64) });
+/// let ndarray: Instance<'ctx, Ptr<F64NDArray>> = model.alloca(generator, ctx);
+/// ```
+///
+/// ...and here is how you may manipulate/access `ndarray`:
+///
+/// (NOTE: some arguments have been omitted)
+///
+/// ```ignore
+/// // Get `&ndarray->data`
+/// ndarray.gep(|f| f.data); // type: Instance<'ctx, Ptr<Float<Float64>>>
+///
+/// // Get `ndarray->ndims`
+/// ndarray.get(|f| f.ndims); // type: Instance<'ctx, Int<SizeT>>
+///
+/// // Get `&ndarray->ndims`
+/// ndarray.gep(|f| f.ndims); // type: Instance<'ctx, Ptr<Int<SizeT>>>
+///
+/// // Get `ndarray->shape[0]`
+/// ndarray.get(|f| f.shape).get_index_const(0); // Instance<'ctx, Int<SizeT>>
+///
+/// // Get `&ndarray->shape[2]`
+/// ndarray.get(|f| f.shape).offset_const(2); // Instance<'ctx, Ptr<Int<SizeT>>>
+///
+/// // Do `ndarray->ndims = 3;`
+/// let num_3 = Int(SizeT).const_int(3);
+/// ndarray.set(|f| f.ndims, num_3);
+/// ```
+pub trait StructKind<'ctx>: fmt::Debug + Clone + Copy {
+    /// The associated fields of this struct.
+    type Fields<F: FieldTraversal<'ctx>>;
+
+    /// Traverse through all fields of this [`StructKind`].
+    ///
+    /// Only used internally in this module for implementing other components.
+    fn iter_fields<F: FieldTraversal<'ctx>>(&self, traversal: &mut F) -> Self::Fields<F>;
+
+    /// Get a convenience structure to get a struct field's GEP index through its corresponding Rust field.
+    ///
+    /// Only used internally in this module for implementing other components.
+    fn fields(&self) -> Self::Fields<GepFieldTraversal> {
+        self.iter_fields(&mut GepFieldTraversal { gep_index_counter: 0 })
+    }
+
+    /// Get the LLVM [`StructType`] of this [`StructKind`].
+    fn get_struct_type<G: CodeGenerator + ?Sized>(
+        &self,
+        generator: &G,
+        ctx: &'ctx Context,
+    ) -> StructType<'ctx> {
+        let mut traversal = TypeFieldTraversal { generator, ctx, field_types: Vec::new() };
+        self.iter_fields(&mut traversal);
+
+        ctx.struct_type(&traversal.field_types, false)
+    }
+}
+
+/// A model for LLVM struct.
+///
+/// `S` should be of a [`StructKind`].
+#[derive(Debug, Clone, Copy, Default)]
+pub struct Struct<S>(pub S);
+
+impl<'ctx, S: StructKind<'ctx>> Struct<S> {
+    /// Create a constant struct value from its fields.
+    ///
+    /// This function also validates `fields` and panic when there is something wrong.
+    pub fn const_struct<G: CodeGenerator + ?Sized>(
+        &self,
+        generator: &mut G,
+        ctx: &'ctx Context,
+        fields: &[BasicValueEnum<'ctx>],
+    ) -> Instance<'ctx, Self> {
+        // NOTE: There *could* have been a functor `F<M> = Instance<'ctx, M>` for `S::Fields<F>`
+        // to create a more user-friendly interface, but Rust's type system is not sophisticated enough
+        // and if you try doing that Rust would force you put lifetimes everywhere.
+        let val = ctx.const_struct(fields, false);
+        self.check_value(generator, ctx, val).unwrap()
+    }
+}
+
+impl<'ctx, S: StructKind<'ctx>> Model<'ctx> for Struct<S> {
+    type Value = StructValue<'ctx>;
+    type Type = StructType<'ctx>;
+
+    fn llvm_type<G: CodeGenerator + ?Sized>(
+        &self,
+        generator: &G,
+        ctx: &'ctx Context,
+    ) -> Self::Type {
+        self.0.get_struct_type(generator, ctx)
+    }
+
+    fn check_type<T: BasicType<'ctx>, G: CodeGenerator + ?Sized>(
+        &self,
+        generator: &mut G,
+        ctx: &'ctx Context,
+        ty: T,
+    ) -> Result<(), ModelError> {
+        let ty = ty.as_basic_type_enum();
+        let Ok(ty) = StructType::try_from(ty) else {
+            return Err(ModelError(format!("Expecting StructType, but got {ty:?}")));
+        };
+
+        // Check each field individually.
+        let mut traversal = CheckTypeFieldTraversal {
+            generator,
+            ctx,
+            gep_index_counter: 0,
+            errors: Vec::new(),
+            scrutinee: ty,
+        };
+        self.0.iter_fields(&mut traversal);
+
+        // Check the number of fields.
+        let exp_num_fields = traversal.gep_index_counter;
+        let got_num_fields = u32::try_from(ty.get_field_types().len()).unwrap();
+        if exp_num_fields != got_num_fields {
+            return Err(ModelError(format!(
+                "Expecting StructType with {exp_num_fields} field(s), but got {got_num_fields}"
+            )));
+        }
+
+        if !traversal.errors.is_empty() {
+            // Currently, only the first error is reported.
+            return Err(traversal.errors[0].clone());
+        }
+
+        Ok(())
+    }
+}
+
+impl<'ctx, S: StructKind<'ctx>> Instance<'ctx, Struct<S>> {
+    /// Get a field with [`StructValue::get_field_at_index`].
+    pub fn get_field<G: CodeGenerator + ?Sized, M, GetField>(
+        &self,
+        generator: &mut G,
+        ctx: &'ctx Context,
+        get_field: GetField,
+    ) -> Instance<'ctx, M>
+    where
+        M: Model<'ctx>,
+        GetField: FnOnce(S::Fields<GepFieldTraversal>) -> GepField<M>,
+    {
+        let field = get_field(self.model.0.fields());
+        let val = self.value.get_field_at_index(field.gep_index).unwrap();
+        field.model.check_value(generator, ctx, val).unwrap()
+    }
+}
+
+impl<'ctx, S: StructKind<'ctx>> Instance<'ctx, Ptr<Struct<S>>> {
+    /// Get a pointer to a field with [`Builder::build_in_bounds_gep`].
+    pub fn gep<M, GetField>(
+        &self,
+        ctx: &CodeGenContext<'ctx, '_>,
+        get_field: GetField,
+    ) -> Instance<'ctx, Ptr<M>>
+    where
+        M: Model<'ctx>,
+        GetField: FnOnce(S::Fields<GepFieldTraversal>) -> GepField<M>,
+    {
+        let field = get_field(self.model.0 .0.fields());
+        let llvm_i32 = ctx.ctx.i32_type();
+
+        let ptr = unsafe {
+            ctx.builder
+                .build_in_bounds_gep(
+                    self.value,
+                    &[llvm_i32.const_zero(), llvm_i32.const_int(u64::from(field.gep_index), false)],
+                    field.name,
+                )
+                .unwrap()
+        };
+
+        unsafe { Ptr(field.model).believe_value(ptr) }
+    }
+
+    /// Convenience function equivalent to `.gep(...).load(...)`.
+    pub fn get<M, GetField, G: CodeGenerator + ?Sized>(
+        &self,
+        generator: &mut G,
+        ctx: &CodeGenContext<'ctx, '_>,
+        get_field: GetField,
+    ) -> Instance<'ctx, M>
+    where
+        M: Model<'ctx>,
+        GetField: FnOnce(S::Fields<GepFieldTraversal>) -> GepField<M>,
+    {
+        self.gep(ctx, get_field).load(generator, ctx)
+    }
+
+    /// Convenience function equivalent to `.gep(...).store(...)`.
+    pub fn set<M, GetField>(
+        &self,
+        ctx: &CodeGenContext<'ctx, '_>,
+        get_field: GetField,
+        value: Instance<'ctx, M>,
+    ) where
+        M: Model<'ctx>,
+        GetField: FnOnce(S::Fields<GepFieldTraversal>) -> GepField<M>,
+    {
+        self.gep(ctx, get_field).store(ctx, value);
+    }
+}

nac3core/src/toplevel/composer.rs

@@ -1,6 +1,6 @@
 use std::rc::Rc;
 
-use nac3parser::ast::{fold::Fold, ExprKind, Ident};
+use nac3parser::ast::{fold::Fold, ExprKind};
 
 use super::*;
 use crate::{
@@ -382,34 +382,54 @@ impl TopLevelComposer {
                 ))
             }
 
-            ast::StmtKind::Assign { .. } => {
-                // Assignment statements can assign to (and therefore create) more than one 
-                // variable, but this function only allows returning one set of symbol information.
-                // We want to avoid changing this to return a `Vec` of symbol info, as this would 
-                // require `iter().next().unwrap()` on every variable created from a non-Assign 
-                // statement.
-                //
-                // Make callers use `register_top_level_var` instead, as it provides more
-                // fine-grained control over which symbols to register, while also simplifying the
-                // usage of this function.
-                panic!("Registration of top-level Assign statements must use TopLevelComposer::register_top_level_var (at {})", ast.location);
-            }
-
             ast::StmtKind::AnnAssign { target, annotation, .. } => {
                 let ExprKind::Name { id: name, .. } = target.node else {
                     return Err(format!(
                         "global variable declaration must be an identifier (at {})",
-                        target.location
+                        ast.location
                     ));
                 };
 
-                self.register_top_level_var(
+                if self.keyword_list.contains(&name) {
+                    return Err(format!(
+                        "cannot use keyword `{}` as a class name (at {})",
+                        name,
+                        ast.location
+                    ));
+                }
+
+                let global_var_name = if mod_path.is_empty() {
+                    name.to_string()
+                } else {
+                    format!("{mod_path}.{name}")
+                };
+                if !defined_names.insert(global_var_name.clone()) {
+                    return Err(format!(
+                        "global variable `{}` defined twice (at {})",
+                        global_var_name,
+                        ast.location
+                    ));
+                }
+
+                let ty_to_be_unified = self.unifier.get_dummy_var().ty;
+                self.definition_ast_list.push((
+                    RwLock::new(Self::make_top_level_variable_def(
+                        global_var_name,
+                        name,
+                        // dummy here, unify with correct type later,
+                        ty_to_be_unified,
+                        *(annotation.clone()),
+                        resolver,
+                        Some(ast.location),
+                    )).into(),
+                    None,
+                ));
+
+                Ok((
                     name,
-                    Some(annotation.as_ref().clone()),
-                    resolver,
-                    mod_path,
-                    target.location,
-                )
+                    DefinitionId(self.definition_ast_list.len() - 1),
+                    Some(ty_to_be_unified),
+                ))
             }
 
             _ => Err(format!(
@@ -419,50 +439,6 @@ impl TopLevelComposer {
         }
     }
 
-    /// Registers a top-level variable with the given `name` into the composer.
-    ///
-    /// `annotation` - The type annotation of the top-level variable, or [`None`] if no type
-    /// annotation is provided.
-    /// `location` - The location of the top-level variable.
-    pub fn register_top_level_var(
-        &mut self,
-        name: Ident,
-        annotation: Option<Expr>,
-        resolver: Option<Arc<dyn SymbolResolver + Send + Sync>>,
-        mod_path: &str,
-        location: Location,
-    ) -> Result<(StrRef, DefinitionId, Option<Type>), String> {
-        if self.keyword_list.contains(&name) {
-            return Err(format!("cannot use keyword `{name}` as a class name (at {location})"));
-        }
-
-        let global_var_name =
-            if mod_path.is_empty() { name.to_string() } else { format!("{mod_path}.{name}") };
-
-        if !self.defined_names.insert(global_var_name.clone()) {
-            return Err(format!(
-                "global variable `{global_var_name}` defined twice (at {location})"
-            ));
-        }
-
-        let ty_to_be_unified = self.unifier.get_dummy_var().ty;
-        self.definition_ast_list.push((
-            RwLock::new(Self::make_top_level_variable_def(
-                global_var_name,
-                name,
-                // dummy here, unify with correct type later,
-                ty_to_be_unified,
-                annotation,
-                resolver,
-                Some(location),
-            ))
-            .into(),
-            None,
-        ));
-
-        Ok((name, DefinitionId(self.definition_ast_list.len() - 1), Some(ty_to_be_unified)))
-    }
-
     pub fn start_analysis(&mut self, inference: bool) -> Result<(), HashSet<String>> {
         self.analyze_top_level_class_type_var()?;
         self.analyze_top_level_class_bases()?;
@@ -509,7 +485,7 @@ impl TopLevelComposer {
                     // things like `class A(Generic[T, V, ImportedModule.T])` is not supported
                     // i.e. only simple names are allowed in the subscript
                     // should update the TopLevelDef::Class.typevars and the TypeEnum::TObj.params
-                    ExprKind::Subscript { value, slice, .. }
+                    ast::ExprKind::Subscript { value, slice, .. }
                         if {
                             matches!(
                                 &value.node,
@@ -525,9 +501,9 @@ impl TopLevelComposer {
                         }
                         is_generic = true;
 
-                        let type_var_list: Vec<&Expr<()>>;
+                        let type_var_list: Vec<&ast::Expr<()>>;
                         // if `class A(Generic[T, V, G])`
-                        if let ExprKind::Tuple { elts, .. } = &slice.node {
+                        if let ast::ExprKind::Tuple { elts, .. } = &slice.node {
                             type_var_list = elts.iter().collect_vec();
                         // `class A(Generic[T])`
                         } else {
@@ -1038,18 +1014,18 @@ impl TopLevelComposer {
                     }
                 }
 
-                let arg_with_default: Vec<(&ast::Located<ast::ArgData<()>>, Option<&Expr>)> = args
-                    .args
-                    .iter()
-                    .rev()
-                    .zip(
-                        args.defaults
-                            .iter()
-                            .rev()
-                            .map(|x| -> Option<&Expr> { Some(x) })
-                            .chain(std::iter::repeat(None)),
-                    )
-                    .collect_vec();
+                let arg_with_default: Vec<(&ast::Located<ast::ArgData<()>>, Option<&ast::Expr>)> =
+                    args.args
+                        .iter()
+                        .rev()
+                        .zip(
+                            args.defaults
+                                .iter()
+                                .rev()
+                                .map(|x| -> Option<&ast::Expr> { Some(x) })
+                                .chain(std::iter::repeat(None)),
+                        )
+                        .collect_vec();
 
                 arg_with_default
                     .iter()
@@ -1307,7 +1283,7 @@ impl TopLevelComposer {
 
                         let arg_with_default: Vec<(
                             &ast::Located<ast::ArgData<()>>,
-                            Option<&Expr>,
+                            Option<&ast::Expr>,
                         )> = args
                             .args
                             .iter()
@@ -1316,7 +1292,7 @@ impl TopLevelComposer {
                                 args.defaults
                                     .iter()
                                     .rev()
-                                    .map(|x| -> Option<&Expr> { Some(x) })
+                                    .map(|x| -> Option<&ast::Expr> { Some(x) })
                                     .chain(std::iter::repeat(None)),
                             )
                             .collect_vec();
@@ -1473,7 +1449,7 @@ impl TopLevelComposer {
                         .map_err(|e| HashSet::from([e.to_display(unifier).to_string()]))?;
                 }
                 ast::StmtKind::AnnAssign { target, annotation, value, .. } => {
-                    if let ExprKind::Name { id: attr, .. } = &target.node {
+                    if let ast::ExprKind::Name { id: attr, .. } = &target.node {
                         if defined_fields.insert(attr.to_string()) {
                             let dummy_field_type = unifier.get_dummy_var().ty;
 
@@ -1481,7 +1457,7 @@ impl TopLevelComposer {
                                 None => {
                                     // handle Kernel[T], KernelInvariant[T]
                                     let (annotation, mutable) = match &annotation.node {
-                                        ExprKind::Subscript { value, slice, .. }
+                                        ast::ExprKind::Subscript { value, slice, .. }
                                             if matches!(
                                                 &value.node,
                                                 ast::ExprKind::Name { id, .. } if id == &core_config.kernel_invariant_ann.into()
@@ -1489,7 +1465,7 @@ impl TopLevelComposer {
                                         {
                                             (slice, false)
                                         }
-                                        ExprKind::Subscript { value, slice, .. }
+                                        ast::ExprKind::Subscript { value, slice, .. }
                                             if matches!(
                                                 &value.node,
                                                 ast::ExprKind::Name { id, .. } if core_config.kernel_ann.map_or(false, |c| id == &c.into())
@@ -1507,13 +1483,13 @@ impl TopLevelComposer {
                                 Some(boxed_expr) => {
                                     // Class attributes are set as immutable regardless
                                     let (annotation, _) = match &annotation.node {
-                                        ExprKind::Subscript { slice, .. } => (slice, false),
+                                        ast::ExprKind::Subscript { slice, .. } => (slice, false),
                                         _ if core_config.kernel_ann.is_none() => (annotation, false),
                                         _ => continue,
                                     };
 
                                     match &**boxed_expr {
-                                        ast::Located {location: _, custom: (), node: ExprKind::Constant { value: v, kind: _ }} => {
+                                        ast::Located {location: _, custom: (), node: ast::ExprKind::Constant { value: v, kind: _ }} => {
                                             // Restricting the types allowed to be defined as class attributes
                                             match v {
                                                 ast::Constant::Bool(_) | ast::Constant::Str(_) | ast::Constant::Int(_) | ast::Constant::Float(_) => {}
@@ -1961,296 +1937,284 @@ impl TopLevelComposer {
             if ast.is_none() {
                 return Ok(());
             }
-
-            let (name, simple_name, signature, resolver) = {
-                let function_def = def.read();
-                let TopLevelDef::Function { name, simple_name, signature, resolver, .. } =
-                    &*function_def
+            let mut function_def = def.write();
+            if let TopLevelDef::Function {
+                instance_to_stmt,
+                instance_to_symbol,
+                name,
+                simple_name,
+                signature,
+                resolver,
+                ..
+            } = &mut *function_def
+            {
+                let signature_ty_enum = unifier.get_ty(*signature);
+                let TypeEnum::TFunc(FunSignature { args, ret, vars, .. }) =
+                    signature_ty_enum.as_ref()
                 else {
-                    return Ok(());
+                    unreachable!("must be typeenum::tfunc")
                 };
 
-                (name.clone(), *simple_name, *signature, resolver.clone())
-            };
+                let mut vars = vars.clone();
+                // None if is not class method
+                let uninst_self_type = {
+                    if let Some(class_id) = method_class.get(&DefinitionId(id)) {
+                        let class_def = definition_ast_list.get(class_id.0).unwrap();
+                        let class_def = class_def.0.read();
+                        let TopLevelDef::Class { type_vars, .. } = &*class_def else {
+                            unreachable!("must be class def")
+                        };
 
-            let signature_ty_enum = unifier.get_ty(signature);
-            let TypeEnum::TFunc(FunSignature { args, ret, vars, .. }) = signature_ty_enum.as_ref()
-            else {
-                unreachable!("must be typeenum::tfunc")
-            };
+                        let ty_ann = make_self_type_annotation(type_vars, *class_id);
+                        let self_ty = get_type_from_type_annotation_kinds(
+                            &def_list,
+                            unifier,
+                            primitives_ty,
+                            &ty_ann,
+                            &mut None,
+                        )?;
+                        vars.extend(type_vars.iter().map(|ty| {
+                            let TypeEnum::TVar { id, .. } = &*unifier.get_ty(*ty) else {
+                                unreachable!()
+                            };
 
-            let mut vars = vars.clone();
-            // None if is not class method
-            let uninst_self_type = {
-                if let Some(class_id) = method_class.get(&DefinitionId(id)) {
-                    let class_def = definition_ast_list.get(class_id.0).unwrap();
-                    let class_def = class_def.0.read();
-                    let TopLevelDef::Class { type_vars, .. } = &*class_def else {
-                        unreachable!("must be class def")
+                            (*id, *ty)
+                        }));
+                        Some((self_ty, type_vars.clone()))
+                    } else {
+                        None
+                    }
+                };
+                // carefully handle those with bounds, without bounds and no typevars
+                // if class methods, `vars` also contains all class typevars here
+                let (type_var_subst_comb, no_range_vars) = {
+                    let mut no_ranges: Vec<Type> = Vec::new();
+                    let var_combs = vars
+                        .values()
+                        .map(|ty| {
+                            unifier.get_instantiations(*ty).unwrap_or_else(|| {
+                                let TypeEnum::TVar { name, loc, is_const_generic: false, .. } =
+                                    &*unifier.get_ty(*ty)
+                                else {
+                                    unreachable!()
+                                };
+
+                                let rigid = unifier.get_fresh_rigid_var(*name, *loc).ty;
+                                no_ranges.push(rigid);
+                                vec![rigid]
+                            })
+                        })
+                        .multi_cartesian_product()
+                        .collect_vec();
+                    let mut result: Vec<VarMap> = Vec::default();
+                    for comb in var_combs {
+                        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(VarMap::new());
+                    }
+                    (result, no_ranges)
+                };
+
+                for subst in type_var_subst_comb {
+                    // for each instance
+                    let inst_ret = unifier.subst(*ret, &subst).unwrap_or(*ret);
+                    let inst_args = {
+                        args.iter()
+                            .map(|a| FuncArg {
+                                name: a.name,
+                                ty: unifier.subst(a.ty, &subst).unwrap_or(a.ty),
+                                default_value: a.default_value.clone(),
+                                is_vararg: false,
+                            })
+                            .collect_vec()
+                    };
+                    let self_type = {
+                        uninst_self_type.clone().map(|(self_type, type_vars)| {
+                            let subst_for_self = {
+                                let class_ty_var_ids = type_vars
+                                    .iter()
+                                    .map(|x| {
+                                        if let TypeEnum::TVar { id, .. } = &*unifier.get_ty(*x) {
+                                            *id
+                                        } else {
+                                            unreachable!("must be type var here");
+                                        }
+                                    })
+                                    .collect::<HashSet<_>>();
+                                subst
+                                    .iter()
+                                    .filter_map(|(ty_var_id, ty_var_target)| {
+                                        if class_ty_var_ids.contains(ty_var_id) {
+                                            Some((*ty_var_id, *ty_var_target))
+                                        } else {
+                                            None
+                                        }
+                                    })
+                                    .collect::<VarMap>()
+                            };
+                            unifier.subst(self_type, &subst_for_self).unwrap_or(self_type)
+                        })
+                    };
+                    let mut identifiers = {
+                        let mut result = HashMap::new();
+                        if self_type.is_some() {
+                            result.insert("self".into(), IdentifierInfo::default());
+                        }
+                        result
+                            .extend(inst_args.iter().map(|x| (x.name, IdentifierInfo::default())));
+                        result
+                    };
+                    let mut calls: HashMap<CodeLocation, CallId> = HashMap::new();
+                    let mut inferencer = Inferencer {
+                        top_level: ctx.as_ref(),
+                        defined_identifiers: identifiers.clone(),
+                        function_data: &mut FunctionData {
+                            resolver: resolver.as_ref().unwrap().clone(),
+                            return_type: if unifier.unioned(inst_ret, primitives_ty.none) {
+                                None
+                            } else {
+                                Some(inst_ret)
+                            },
+                            // NOTE: allowed type vars
+                            bound_variables: no_range_vars.clone(),
+                        },
+                        unifier,
+                        variable_mapping: {
+                            let mut result: HashMap<StrRef, Type> = HashMap::new();
+                            if let Some(self_ty) = self_type {
+                                result.insert("self".into(), self_ty);
+                            }
+                            result.extend(inst_args.iter().map(|x| (x.name, x.ty)));
+                            result
+                        },
+                        primitives: primitives_ty,
+                        virtual_checks: &mut Vec::new(),
+                        calls: &mut calls,
+                        in_handler: false,
                     };
 
-                    let ty_ann = make_self_type_annotation(type_vars, *class_id);
-                    let self_ty = get_type_from_type_annotation_kinds(
-                        &def_list,
-                        unifier,
-                        primitives_ty,
-                        &ty_ann,
-                        &mut None,
-                    )?;
-                    vars.extend(type_vars.iter().map(|ty| {
-                        let TypeEnum::TVar { id, .. } = &*unifier.get_ty(*ty) else {
-                            unreachable!()
-                        };
-
-                        (*id, *ty)
-                    }));
-                    Some((self_ty, type_vars.clone()))
-                } else {
-                    None
-                }
-            };
-            // carefully handle those with bounds, without bounds and no typevars
-            // if class methods, `vars` also contains all class typevars here
-            let (type_var_subst_comb, no_range_vars) = {
-                let mut no_ranges: Vec<Type> = Vec::new();
-                let var_combs = vars
-                    .values()
-                    .map(|ty| {
-                        unifier.get_instantiations(*ty).unwrap_or_else(|| {
-                            let TypeEnum::TVar { name, loc, is_const_generic: false, .. } =
-                                &*unifier.get_ty(*ty)
-                            else {
-                                unreachable!()
-                            };
-
-                            let rigid = unifier.get_fresh_rigid_var(*name, *loc).ty;
-                            no_ranges.push(rigid);
-                            vec![rigid]
-                        })
-                    })
-                    .multi_cartesian_product()
-                    .collect_vec();
-                let mut result: Vec<VarMap> = Vec::default();
-                for comb in var_combs {
-                    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(VarMap::new());
-                }
-                (result, no_ranges)
-            };
-
-            for subst in type_var_subst_comb {
-                // for each instance
-                let inst_ret = unifier.subst(*ret, &subst).unwrap_or(*ret);
-                let inst_args = {
-                    args.iter()
-                        .map(|a| FuncArg {
-                            name: a.name,
-                            ty: unifier.subst(a.ty, &subst).unwrap_or(a.ty),
-                            default_value: a.default_value.clone(),
-                            is_vararg: false,
-                        })
-                        .collect_vec()
-                };
-                let self_type = {
-                    uninst_self_type.clone().map(|(self_type, type_vars)| {
-                        let subst_for_self = {
-                            let class_ty_var_ids = type_vars
-                                .iter()
-                                .map(|x| {
-                                    if let TypeEnum::TVar { id, .. } = &*unifier.get_ty(*x) {
-                                        *id
-                                    } else {
-                                        unreachable!("must be type var here");
-                                    }
-                                })
-                                .collect::<HashSet<_>>();
-                            subst
-                                .iter()
-                                .filter_map(|(ty_var_id, ty_var_target)| {
-                                    if class_ty_var_ids.contains(ty_var_id) {
-                                        Some((*ty_var_id, *ty_var_target))
-                                    } else {
-                                        None
-                                    }
-                                })
-                                .collect::<VarMap>()
-                        };
-                        unifier.subst(self_type, &subst_for_self).unwrap_or(self_type)
-                    })
-                };
-                let mut identifiers = {
-                    let mut result = HashMap::new();
-                    if self_type.is_some() {
-                        result.insert("self".into(), IdentifierInfo::default());
-                    }
-                    result.extend(inst_args.iter().map(|x| (x.name, IdentifierInfo::default())));
-                    result
-                };
-                let mut calls: HashMap<CodeLocation, CallId> = HashMap::new();
-                let mut inferencer = Inferencer {
-                    top_level: ctx.as_ref(),
-                    defined_identifiers: identifiers.clone(),
-                    function_data: &mut FunctionData {
-                        resolver: resolver.as_ref().unwrap().clone(),
-                        return_type: if unifier.unioned(inst_ret, primitives_ty.none) {
-                            None
-                        } else {
-                            Some(inst_ret)
-                        },
-                        // NOTE: allowed type vars
-                        bound_variables: no_range_vars.clone(),
-                    },
-                    unifier,
-                    variable_mapping: {
-                        let mut result: HashMap<StrRef, Type> = HashMap::new();
-                        if let Some(self_ty) = self_type {
-                            result.insert("self".into(), self_ty);
-                        }
-                        result.extend(inst_args.iter().map(|x| (x.name, x.ty)));
-                        result
-                    },
-                    primitives: primitives_ty,
-                    virtual_checks: &mut Vec::new(),
-                    calls: &mut calls,
-                    in_handler: false,
-                };
-
-                let ast::StmtKind::FunctionDef { body, decorator_list, .. } =
-                    ast.clone().unwrap().node
-                else {
-                    unreachable!("must be function def ast")
-                };
-
-                if !decorator_list.is_empty() {
-                    if matches!(&decorator_list[0].node, ExprKind::Name { id, .. } if id == &"extern".into())
+                    let ast::StmtKind::FunctionDef { body, decorator_list, .. } =
+                        ast.clone().unwrap().node
+                    else {
+                        unreachable!("must be function def ast")
+                    };
+                    if !decorator_list.is_empty()
+                        && matches!(&decorator_list[0].node,
+                            ast::ExprKind::Name{ id, .. } if id == &"extern".into())
                     {
-                        let TopLevelDef::Function { instance_to_symbol, .. } = &mut *def.write()
-                        else {
-                            unreachable!()
-                        };
                         instance_to_symbol.insert(String::new(), simple_name.to_string());
                         continue;
                     }
-
-                    if matches!(&decorator_list[0].node, ExprKind::Name { id, .. } if id == &"rpc".into())
+                    if !decorator_list.is_empty()
+                        && matches!(&decorator_list[0].node,
+                            ast::ExprKind::Name{ id, .. } if id == &"rpc".into())
                     {
-                        let TopLevelDef::Function { instance_to_symbol, .. } = &mut *def.write()
-                        else {
-                            unreachable!()
-                        };
                         instance_to_symbol.insert(String::new(), simple_name.to_string());
                         continue;
                     }
-
-                    if let ExprKind::Call { func, .. } = &decorator_list[0].node {
-                        if matches!(&func.node, ExprKind::Name { id, .. } if id == &"rpc".into()) {
-                            let TopLevelDef::Function { instance_to_symbol, .. } =
-                                &mut *def.write()
-                            else {
-                                unreachable!()
-                            };
-                            instance_to_symbol.insert(String::new(), simple_name.to_string());
-                            continue;
+                    if !decorator_list.is_empty() {
+                        if let ast::ExprKind::Call { func, .. } = &decorator_list[0].node {
+                            if matches!(&func.node,
+                                ast::ExprKind::Name{ id, .. } if id == &"rpc".into())
+                            {
+                                instance_to_symbol.insert(String::new(), simple_name.to_string());
+                                continue;
+                            }
                         }
                     }
-                }
 
-                let fun_body =
-                    body.into_iter()
+                    let fun_body = body
+                        .into_iter()
                         .map(|b| inferencer.fold_stmt(b))
                         .collect::<Result<Vec<_>, _>>()?;
 
-                let returned = inferencer.check_block(fun_body.as_slice(), &mut identifiers)?;
-                {
-                    // check virtuals
-                    let defs = ctx.definitions.read();
-                    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(HashSet::from([format!(
-                                    "Base type should be a class (at {loc})"
-                                )]));
-                            }
-                        };
-                        let subtype_id = {
-                            let ty = inferencer.unifier.get_ty(*subtype);
-                            if let TypeEnum::TObj { obj_id, .. } = &*ty {
-                                *obj_id
-                            } else {
+                    let returned = inferencer.check_block(fun_body.as_slice(), &mut identifiers)?;
+                    {
+                        // check virtuals
+                        let defs = ctx.definitions.read();
+                        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(HashSet::from([format!(
+                                        "Base type should be a class (at {loc})"
+                                    )]));
+                                }
+                            };
+                            let subtype_id = {
+                                let ty = inferencer.unifier.get_ty(*subtype);
+                                if let TypeEnum::TObj { obj_id, .. } = &*ty {
+                                    *obj_id
+                                } else {
+                                    let base_repr = inferencer.unifier.stringify(*base);
+                                    let subtype_repr = inferencer.unifier.stringify(*subtype);
+                                    return Err(HashSet::from([format!(
+                                        "Expected a subtype of {base_repr}, but got {subtype_repr} (at {loc})"),
+                                    ]));
+                                }
+                            };
+                            let subtype_entry = defs[subtype_id.0].read();
+                            let TopLevelDef::Class { ancestors, .. } = &*subtype_entry else {
+                                unreachable!()
+                            };
+
+                            let m = ancestors.iter()
+                                .find(|kind| matches!(kind, TypeAnnotation::CustomClass { id, .. } if *id == base_id));
+                            if m.is_none() {
                                 let base_repr = inferencer.unifier.stringify(*base);
                                 let subtype_repr = inferencer.unifier.stringify(*subtype);
                                 return Err(HashSet::from([format!(
                                     "Expected a subtype of {base_repr}, but got {subtype_repr} (at {loc})"),
                                 ]));
                             }
-                        };
-                        let subtype_entry = defs[subtype_id.0].read();
-                        let TopLevelDef::Class { ancestors, .. } = &*subtype_entry else {
-                            unreachable!()
-                        };
-
-                        let m = ancestors.iter()
-                            .find(|kind| matches!(kind, TypeAnnotation::CustomClass { id, .. } if *id == base_id));
-                        if m.is_none() {
-                            let base_repr = inferencer.unifier.stringify(*base);
-                            let subtype_repr = inferencer.unifier.stringify(*subtype);
-                            return Err(HashSet::from([format!(
-                                "Expected a subtype of {base_repr}, but got {subtype_repr} (at {loc})"),
-                            ]));
                         }
                     }
-                }
-                if !unifier.unioned(inst_ret, primitives_ty.none) && !returned {
-                    let def_ast_list = &definition_ast_list;
-                    let ret_str = unifier.internal_stringify(
-                        inst_ret,
-                        &mut |id| {
-                            let TopLevelDef::Class { name, .. } = &*def_ast_list[id].0.read()
-                            else {
-                                unreachable!("must be class id here")
-                            };
+                    if !unifier.unioned(inst_ret, primitives_ty.none) && !returned {
+                        let def_ast_list = &definition_ast_list;
+                        let ret_str = unifier.internal_stringify(
+                            inst_ret,
+                            &mut |id| {
+                                let TopLevelDef::Class { name, .. } = &*def_ast_list[id].0.read()
+                                else {
+                                    unreachable!("must be class id here")
+                                };
 
-                            name.to_string()
+                                name.to_string()
+                            },
+                            &mut |id| format!("typevar{id}"),
+                            &mut None,
+                        );
+                        return Err(HashSet::from([format!(
+                            "expected return type of `{}` in function `{}` (at {})",
+                            ret_str,
+                            name,
+                            ast.as_ref().unwrap().location
+                        )]));
+                    }
+
+                    instance_to_stmt.insert(
+                        get_subst_key(
+                            unifier,
+                            self_type,
+                            &subst,
+                            Some(&vars.keys().copied().collect()),
+                        ),
+                        FunInstance {
+                            body: Arc::new(fun_body),
+                            unifier_id: 0,
+                            calls: Arc::new(calls),
+                            subst,
                         },
-                        &mut |id| format!("typevar{id}"),
-                        &mut None,
                     );
-                    return Err(HashSet::from([format!(
-                        "expected return type of `{}` in function `{}` (at {})",
-                        ret_str,
-                        name,
-                        ast.as_ref().unwrap().location
-                    )]));
                 }
-
-                let TopLevelDef::Function { instance_to_stmt, .. } = &mut *def.write() else {
-                    unreachable!()
-                };
-                instance_to_stmt.insert(
-                    get_subst_key(
-                        unifier,
-                        self_type,
-                        &subst,
-                        Some(&vars.keys().copied().collect()),
-                    ),
-                    FunInstance {
-                        body: Arc::new(fun_body),
-                        unifier_id: 0,
-                        calls: Arc::new(calls),
-                        subst,
-                    },
-                );
             }
 
             Ok(())
         };
-
         for (id, (def, ast)) in self.definition_ast_list.iter().enumerate().skip(self.builtin_num) {
             if ast.is_none() {
                 continue;
@@ -2273,8 +2237,9 @@ impl TopLevelComposer {
         let primitives_store = &self.primitives_ty;
 
         let mut analyze = |variable_def: &Arc<RwLock<TopLevelDef>>| -> Result<_, HashSet<String>> {
-            let TopLevelDef::Variable { ty: dummy_ty, ty_decl, resolver, loc, .. } =
-                &*variable_def.read()
+            let variable_def = &mut *variable_def.write();
+
+            let TopLevelDef::Variable { ty: dummy_ty, ty_decl, resolver, loc, .. } = variable_def
             else {
                 // not top level variable def, skip
                 return Ok(());
@@ -2282,28 +2247,25 @@ impl TopLevelComposer {
 
             let resolver = &**resolver.as_ref().unwrap();
 
-            if let Some(ty_decl) = ty_decl {
-                let ty_annotation = parse_ast_to_type_annotation_kinds(
-                    resolver,
-                    &temp_def_list,
-                    unifier,
-                    primitives_store,
-                    ty_decl,
-                    HashMap::new(),
-                )?;
-                let ty_from_ty_annotation = get_type_from_type_annotation_kinds(
-                    &temp_def_list,
-                    unifier,
-                    primitives_store,
-                    &ty_annotation,
-                    &mut None,
-                )?;
-
-                unifier.unify(*dummy_ty, ty_from_ty_annotation).map_err(|e| {
-                    HashSet::from([e.at(Some(loc.unwrap())).to_display(unifier).to_string()])
-                })?;
-            }
+            let ty_annotation = parse_ast_to_type_annotation_kinds(
+                resolver,
+                &temp_def_list,
+                unifier,
+                primitives_store,
+                ty_decl,
+                HashMap::new(),
+            )?;
+            let ty_from_ty_annotation = get_type_from_type_annotation_kinds(
+                &temp_def_list,
+                unifier,
+                primitives_store,
+                &ty_annotation,
+                &mut None,
+            )?;
 
+            unifier.unify(*dummy_ty, ty_from_ty_annotation).map_err(|e| {
+                HashSet::from([e.at(Some(loc.unwrap())).to_display(unifier).to_string()])
+            })?;
             Ok(())
         };
 

nac3core/src/toplevel/helper.rs

@@ -600,7 +600,7 @@ impl TopLevelComposer {
         name: String,
         simple_name: StrRef,
         ty: Type,
-        ty_decl: Option<Expr>,
+        ty_decl: Expr,
         resolver: Option<Arc<dyn SymbolResolver + Send + Sync>>,
         loc: Option<Location>,
     ) -> TopLevelDef {

nac3core/src/toplevel/mod.rs

@@ -158,8 +158,8 @@ pub enum TopLevelDef {
         /// Type of the global variable.
         ty: Type,
 
-        /// The declared type of the global variable, or [`None`] if no type annotation is provided.
-        ty_decl: Option<Expr>,
+        /// The declared type of the global variable.
+        ty_decl: Expr,
 
         /// Symbol resolver of the module defined the class.
         resolver: Option<Arc<dyn SymbolResolver + Send + Sync>>,

nac3core/src/typecheck/function_check.rs

@@ -10,7 +10,7 @@ use nac3parser::ast::{
 };
 
 use super::{
-    type_inferencer::{DeclarationSource, IdentifierInfo, Inferencer},
+    type_inferencer::{IdentifierInfo, Inferencer},
     typedef::{Type, TypeEnum},
 };
 use crate::toplevel::helper::PrimDef;
@@ -34,20 +34,6 @@ impl<'a> Inferencer<'a> {
                 Err(HashSet::from([format!("cannot assign to a `none` (at {})", pattern.location)]))
             }
             ExprKind::Name { id, .. } => {
-                // If `id` refers to a declared symbol, reject this assignment if it is used in the
-                // context of an (implicit) global variable
-                if let Some(id_info) = defined_identifiers.get(id) {
-                    if matches!(
-                        id_info.source,
-                        DeclarationSource::Global { is_explicit: Some(false) }
-                    ) {
-                        return Err(HashSet::from([format!(
-                            "cannot access local variable '{id}' before it is declared (at {})",
-                            pattern.location
-                        )]));
-                    }
-                }
-
                 if !defined_identifiers.contains_key(id) {
                     defined_identifiers.insert(*id, IdentifierInfo::default());
                 }
@@ -118,22 +104,7 @@ impl<'a> Inferencer<'a> {
                         *id,
                     ) {
                         Ok(_) => {
-                            let is_global = self.is_id_global(*id);
-
-                            defined_identifiers.insert(
-                                *id,
-                                IdentifierInfo {
-                                    source: match is_global {
-                                        Some(true) => {
-                                            DeclarationSource::Global { is_explicit: Some(false) }
-                                        }
-                                        Some(false) => {
-                                            DeclarationSource::Global { is_explicit: None }
-                                        }
-                                        None => DeclarationSource::Local,
-                                    },
-                                },
-                            );
+                            self.defined_identifiers.insert(*id, IdentifierInfo::default());
                         }
                         Err(e) => {
                             return Err(HashSet::from([format!(
@@ -397,9 +368,9 @@ impl<'a> Inferencer<'a> {
             StmtKind::Global { names, .. } => {
                 for id in names {
                     if let Some(id_info) = defined_identifiers.get(id) {
-                        if id_info.source == DeclarationSource::Local {
+                        if !id_info.is_global {
                             return Err(HashSet::from([format!(
-                                "name '{id}' is referenced prior to global declaration at {}",
+                                "name '{id}' is assigned to before global declaration at {}",
                                 stmt.location,
                             )]));
                         }
@@ -414,12 +385,8 @@ impl<'a> Inferencer<'a> {
                         *id,
                     ) {
                         Ok(_) => {
-                            defined_identifiers.insert(
-                                *id,
-                                IdentifierInfo {
-                                    source: DeclarationSource::Global { is_explicit: Some(true) },
-                                },
-                            );
+                            self.defined_identifiers
+                                .insert(*id, IdentifierInfo { is_global: true });
                         }
                         Err(e) => {
                             return Err(HashSet::from([format!(

nac3core/src/typecheck/type_inferencer/mod.rs

@@ -12,7 +12,7 @@ use itertools::{izip, Itertools};
 use nac3parser::ast::{
     self,
     fold::{self, Fold},
-    Arguments, Comprehension, ExprContext, ExprKind, Ident, Located, Location, StrRef,
+    Arguments, Comprehension, ExprContext, ExprKind, Located, Location, StrRef,
 };
 
 use super::{
@@ -88,31 +88,11 @@ impl PrimitiveStore {
     }
 }
 
-/// The location where an identifier declaration refers to.
-#[derive(Clone, Copy, Debug, Eq, PartialEq)]
-pub enum DeclarationSource {
-    /// Local scope.
-    Local,
-
-    /// Global scope.
-    Global {
-        /// Whether the identifier is declared by the use of `global` statement. This field is
-        /// [`None`] if the identifier does not refer to a variable.
-        is_explicit: Option<bool>,
-    },
-}
-
 /// Information regarding a defined identifier.
-#[derive(Clone, Copy, Debug)]
+#[derive(Clone, Copy, Debug, Default)]
 pub struct IdentifierInfo {
     /// Whether this identifier refers to a global variable.
-    pub source: DeclarationSource,
-}
-
-impl Default for IdentifierInfo {
-    fn default() -> Self {
-        IdentifierInfo { source: DeclarationSource::Local }
-    }
+    pub is_global: bool,
 }
 
 impl IdentifierInfo {
@@ -594,22 +574,7 @@ impl<'a> Fold<()> for Inferencer<'a> {
                             *id,
                         ) {
                             Ok(_) => {
-                                let is_global = self.is_id_global(*id);
-
-                                self.defined_identifiers.insert(
-                                    *id,
-                                    IdentifierInfo {
-                                        source: match is_global {
-                                            Some(true) => DeclarationSource::Global {
-                                                is_explicit: Some(false),
-                                            },
-                                            Some(false) => {
-                                                DeclarationSource::Global { is_explicit: None }
-                                            }
-                                            None => DeclarationSource::Local,
-                                        },
-                                    },
-                                );
+                                self.defined_identifiers.insert(*id, IdentifierInfo::default());
                             }
                             Err(e) => {
                                 return report_error(
@@ -2685,22 +2650,4 @@ impl<'a> Inferencer<'a> {
         self.constrain(body.custom.unwrap(), orelse.custom.unwrap(), &body.location)?;
         Ok(body.custom.unwrap())
     }
-
-    /// Determines whether the given `id` refers to a global symbol.
-    ///
-    /// Returns `Some(true)` if `id` refers to a global variable, `Some(false)` if `id` refers to a
-    /// class/function, and `None` if `id` refers to a local symbol.
-    pub(super) fn is_id_global(&self, id: Ident) -> Option<bool> {
-        self.top_level
-            .definitions
-            .read()
-            .iter()
-            .map(|def| match *def.read() {
-                TopLevelDef::Class { name, .. } => (name, false),
-                TopLevelDef::Function { simple_name, .. } => (simple_name, false),
-                TopLevelDef::Variable { simple_name, .. } => (simple_name, true),
-            })
-            .find(|(global, _)| global == &id)
-            .map(|(_, has_explicit_prop)| has_explicit_prop)
-    }
 }

nac3standalone/demo/src/globals.py

@@ -7,7 +7,7 @@ def output_int64(x: int64):
     ...
 
 X: int32 = 0
-Y = int64(1)
+Y: int64 = int64(1)
 
 def f():
     global X, Y

nac3standalone/src/main.rs

@@ -174,49 +174,46 @@ fn handle_typevar_definition(
 fn handle_assignment_pattern(
     targets: &[Expr],
     value: &Expr,
-    resolver: Arc<dyn SymbolResolver + Send + Sync>,
+    resolver: &(dyn SymbolResolver + Send + Sync),
     internal_resolver: &ResolverInternal,
-    composer: &mut TopLevelComposer,
+    def_list: &[Arc<RwLock<TopLevelDef>>],
+    unifier: &mut Unifier,
+    primitives: &PrimitiveStore,
 ) -> Result<(), String> {
     if targets.len() == 1 {
-        let target = &targets[0];
-
-        match &target.node {
+        match &targets[0].node {
             ExprKind::Name { id, .. } => {
-                let def_list = composer.extract_def_list();
-                let unifier = &mut composer.unifier;
-                let primitives = &composer.primitives_ty;
-
                 if let Ok(var) =
-                    handle_typevar_definition(value, &*resolver, &def_list, unifier, primitives)
+                    handle_typevar_definition(value, resolver, def_list, unifier, primitives)
                 {
                     internal_resolver.add_id_type(*id, var);
                     Ok(())
-                } else if let Ok(val) = parse_parameter_default_value(value, &*resolver) {
+                } else if let Ok(val) = parse_parameter_default_value(value, resolver) {
                     internal_resolver.add_module_global(*id, val);
-                    let (name, def_id, _) = composer
-                        .register_top_level_var(
-                            *id,
-                            None,
-                            Some(resolver.clone()),
-                            "__main__",
-                            target.location,
-                        )
-                        .unwrap();
-                    internal_resolver.add_id_def(name, def_id);
                     Ok(())
                 } else {
                     Err(format!("fails to evaluate this expression `{:?}` as a constant or generic parameter at {}",
-                        target.node,
-                        target.location,
+                        targets[0].node,
+                        targets[0].location,
                     ))
                 }
             }
             ExprKind::List { elts, .. } | ExprKind::Tuple { elts, .. } => {
-                handle_assignment_pattern(elts, value, resolver, internal_resolver, composer)?;
+                handle_assignment_pattern(
+                    elts,
+                    value,
+                    resolver,
+                    internal_resolver,
+                    def_list,
+                    unifier,
+                    primitives,
+                )?;
                 Ok(())
             }
-            _ => Err(format!("assignment to {target:?} is not supported at {}", target.location)),
+            _ => Err(format!(
+                "assignment to {:?} is not supported at {}",
+                targets[0], targets[0].location
+            )),
         }
     } else {
         match &value.node {
@@ -226,9 +223,11 @@ fn handle_assignment_pattern(
                         handle_assignment_pattern(
                             std::slice::from_ref(tar),
                             val,
-                            resolver.clone(),
+                            resolver,
                             internal_resolver,
-                            composer,
+                            def_list,
+                            unifier,
+                            primitives,
                         )?;
                     }
                     Ok(())
@@ -249,9 +248,8 @@ fn handle_assignment_pattern(
 fn handle_global_var(
     target: &Expr,
     value: Option<&Expr>,
-    resolver: &Arc<dyn SymbolResolver + Send + Sync>,
+    resolver: &(dyn SymbolResolver + Send + Sync),
     internal_resolver: &ResolverInternal,
-    composer: &mut TopLevelComposer,
 ) -> Result<(), String> {
     let ExprKind::Name { id, .. } = target.node else {
         return Err(format!(
@@ -264,12 +262,8 @@ fn handle_global_var(
         return Err(format!("global variable `{id}` must be initialized in its definition"));
     };
 
-    if let Ok(val) = parse_parameter_default_value(value, &**resolver) {
+    if let Ok(val) = parse_parameter_default_value(value, resolver) {
         internal_resolver.add_module_global(id, val);
-        let (name, def_id, _) = composer
-            .register_top_level_var(id, None, Some(resolver.clone()), "__main__", target.location)
-            .unwrap();
-        internal_resolver.add_id_def(name, def_id);
         Ok(())
     } else {
         Err(format!(
@@ -361,12 +355,17 @@ fn main() {
     for stmt in parser_result {
         match &stmt.node {
             StmtKind::Assign { targets, value, .. } => {
+                let def_list = composer.extract_def_list();
+                let unifier = &mut composer.unifier;
+                let primitives = &composer.primitives_ty;
                 if let Err(err) = handle_assignment_pattern(
                     targets,
                     value,
-                    resolver.clone(),
+                    resolver.as_ref(),
                     internal_resolver.as_ref(),
-                    &mut composer,
+                    &def_list,
+                    unifier,
+                    primitives,
                 ) {
                     panic!("{err}");
                 }
@@ -376,12 +375,16 @@ fn main() {
                 if let Err(err) = handle_global_var(
                     target,
                     value.as_ref().map(Box::as_ref),
-                    &resolver,
+                    resolver.as_ref(),
                     internal_resolver.as_ref(),
-                    &mut composer,
                 ) {
                     panic!("{err}");
                 }
+
+                let (name, def_id, _) = composer
+                    .register_top_level(stmt, Some(resolver.clone()), "__main__", true)
+                    .unwrap();
+                internal_resolver.add_id_def(name, def_id);
             }
 
             // allow (and ignore) "from __future__ import annotations"