allow ListObject to have TVar item_type

fix binop +

nac3artiq/src/codegen.rs

@@ -1,10 +1,9 @@
 use nac3core::{
     codegen::{
-        classes::{ListValue, UntypedArrayLikeAccessor},
         expr::gen_call,
         llvm_intrinsics::{call_int_smax, call_stackrestore, call_stacksave},
         model::*,
-        object::{any::AnyObject, ndarray::NDArrayObject, range::RangeObject},
+        object::{any::AnyObject, list::ListObject, ndarray::NDArrayObject, range::RangeObject},
         stmt::{gen_block, gen_for_callback_incrementing, gen_if_callback, gen_with},
         CodeGenContext, CodeGenerator,
     },
@@ -1015,14 +1014,16 @@ fn polymorphic_print<'ctx>(
                 args.extend(&[str_len.into(), str_data.into()]);
             }
 
-            TypeEnum::TObj { obj_id, params, .. } if *obj_id == PrimDef::List.id() => {
-                let elem_ty = *params.iter().next().unwrap().1;
-
+            TypeEnum::TObj { obj_id, .. } if *obj_id == PrimDef::List.id() => {
                 fmt.push('[');
                 flush(ctx, generator, &mut fmt, &mut args);
 
-                let val = ListValue::from_ptr_val(value.into_pointer_value(), llvm_usize, None);
-                let len = val.load_size(ctx, None);
+                let list = AnyObject { ty, value };
+                let list = ListObject::from_object(generator, ctx, list);
+
+                let items = list.instance.get(generator, ctx, |f| f.items);
+
+                let len = list.instance.get(generator, ctx, |f| f.len).value;
                 let last =
                     ctx.builder.build_int_sub(len, llvm_usize.const_int(1, false), "").unwrap();
 
@@ -1033,12 +1034,12 @@ fn polymorphic_print<'ctx>(
                     llvm_usize.const_zero(),
                     (len, false),
                     |generator, ctx, _, i| {
-                        let elem = unsafe { val.data().get_unchecked(ctx, generator, &i, None) };
+                        let item = items.get_index(generator, ctx, i).value;
 
                         polymorphic_print(
                             ctx,
                             generator,
-                            &[(elem_ty, elem.into())],
+                            &[(list.item_type, item.into())],
                             "",
                             None,
                             true,

nac3core/irrt/irrt/ndarray/indexing.hpp

@@ -68,13 +68,9 @@ namespace indexing
 /**
  * @brief Perform ndarray "basic indexing" (https://numpy.org/doc/stable/user/basics.indexing.html#basic-indexing)
  *
- * This is function very similar to performing `dst_ndarray = src_ndarray[indices]` in Python (where the variables
- * can all be found in the parameter of this function).
+ * This function is very similar to performing `dst_ndarray = src_ndarray[indices]` in Python.
  *
- * In other words, this function takes in an ndarray (`src_ndarray`), index it with `indices`, and return the
- * indexed array (by writing the result to `dst_ndarray`).
- *
- * This function also does proper assertions on `indices`.
+ * This function also does proper assertions on `indices` to check for out of bounds access.
  *
  * # Notes on `dst_ndarray`
  * The caller is responsible for allocating space for the resulting ndarray.

nac3core/src/codegen/classes.rs

@@ -1,11 +1,10 @@
 use crate::codegen::{CodeGenContext, CodeGenerator};
-use inkwell::context::Context;
-use inkwell::types::{BasicType, StructType};
-use inkwell::values::{BasicValue, StructValue};
+use inkwell::types::BasicType;
+use inkwell::values::BasicValue;
 use inkwell::{
-    types::{AnyTypeEnum, BasicTypeEnum, IntType, PointerType},
+    types::AnyTypeEnum,
     values::{BasicValueEnum, IntValue, PointerValue},
-    AddressSpace, IntPredicate,
+    IntPredicate,
 };
 
 /// A LLVM type that is used to represent a non-primitive type in NAC3.
@@ -502,374 +501,3 @@ impl<'ctx> ArrayLikeIndexer<'ctx> for ArraySliceValue<'ctx> {
 
 impl<'ctx> UntypedArrayLikeAccessor<'ctx> for ArraySliceValue<'ctx> {}
 impl<'ctx> UntypedArrayLikeMutator<'ctx> for ArraySliceValue<'ctx> {}
-
-/// Proxy type for a `list` type in LLVM.
-#[derive(Debug, PartialEq, Eq, Clone, Copy)]
-pub struct ListType<'ctx> {
-    ty: PointerType<'ctx>,
-    llvm_usize: IntType<'ctx>,
-}
-
-impl<'ctx> ListType<'ctx> {
-    /// Checks whether `llvm_ty` represents a `list` type, returning [Err] if it does not.
-    pub fn is_type(llvm_ty: PointerType<'ctx>, llvm_usize: IntType<'ctx>) -> Result<(), String> {
-        let llvm_list_ty = llvm_ty.get_element_type();
-        let AnyTypeEnum::StructType(llvm_list_ty) = llvm_list_ty else {
-            return Err(format!("Expected struct type for `list` type, got {llvm_list_ty}"));
-        };
-        if llvm_list_ty.count_fields() != 2 {
-            return Err(format!(
-                "Expected 2 fields in `list`, got {}",
-                llvm_list_ty.count_fields()
-            ));
-        }
-
-        let list_size_ty = llvm_list_ty.get_field_type_at_index(0).unwrap();
-        let Ok(_) = PointerType::try_from(list_size_ty) else {
-            return Err(format!("Expected pointer type for `list.0`, got {list_size_ty}"));
-        };
-
-        let list_data_ty = llvm_list_ty.get_field_type_at_index(1).unwrap();
-        let Ok(list_data_ty) = IntType::try_from(list_data_ty) else {
-            return Err(format!("Expected int type for `list.1`, got {list_data_ty}"));
-        };
-        if list_data_ty.get_bit_width() != llvm_usize.get_bit_width() {
-            return Err(format!(
-                "Expected {}-bit int type for `list.1`, got {}-bit int",
-                llvm_usize.get_bit_width(),
-                list_data_ty.get_bit_width()
-            ));
-        }
-
-        Ok(())
-    }
-
-    /// Creates an instance of [`ListType`].
-    #[must_use]
-    pub fn new<G: CodeGenerator + ?Sized>(
-        generator: &G,
-        ctx: &'ctx Context,
-        element_type: BasicTypeEnum<'ctx>,
-    ) -> Self {
-        let llvm_usize = generator.get_size_type(ctx);
-        let llvm_list = ctx
-            .struct_type(
-                &[element_type.ptr_type(AddressSpace::default()).into(), llvm_usize.into()],
-                false,
-            )
-            .ptr_type(AddressSpace::default());
-
-        ListType::from_type(llvm_list, llvm_usize)
-    }
-
-    /// Creates an [`ListType`] from a [`PointerType`].
-    #[must_use]
-    pub fn from_type(ptr_ty: PointerType<'ctx>, llvm_usize: IntType<'ctx>) -> Self {
-        debug_assert!(Self::is_type(ptr_ty, llvm_usize).is_ok());
-
-        ListType { ty: ptr_ty, llvm_usize }
-    }
-
-    /// Returns the type of the `size` field of this `list` type.
-    #[must_use]
-    pub fn size_type(&self) -> IntType<'ctx> {
-        self.as_base_type()
-            .get_element_type()
-            .into_struct_type()
-            .get_field_type_at_index(1)
-            .map(BasicTypeEnum::into_int_type)
-            .unwrap()
-    }
-
-    /// Returns the element type of this `list` type.
-    #[must_use]
-    pub fn element_type(&self) -> AnyTypeEnum<'ctx> {
-        self.as_base_type()
-            .get_element_type()
-            .into_struct_type()
-            .get_field_type_at_index(0)
-            .map(BasicTypeEnum::into_pointer_type)
-            .map(PointerType::get_element_type)
-            .unwrap()
-    }
-}
-
-impl<'ctx> ProxyType<'ctx> for ListType<'ctx> {
-    type Base = PointerType<'ctx>;
-    type Underlying = StructType<'ctx>;
-    type Value = ListValue<'ctx>;
-
-    fn new_value<G: CodeGenerator + ?Sized>(
-        &self,
-        generator: &mut G,
-        ctx: &mut CodeGenContext<'ctx, '_>,
-        name: Option<&'ctx str>,
-    ) -> Self::Value {
-        self.create_value(
-            generator.gen_var_alloc(ctx, self.as_underlying_type().into(), name).unwrap(),
-            name,
-        )
-    }
-
-    fn create_value(
-        &self,
-        value: <Self::Value as ProxyValue<'ctx>>::Base,
-        name: Option<&'ctx str>,
-    ) -> Self::Value {
-        debug_assert_eq!(value.get_type(), self.as_base_type());
-
-        ListValue { value, llvm_usize: self.llvm_usize, name }
-    }
-
-    fn as_base_type(&self) -> Self::Base {
-        self.ty
-    }
-
-    fn as_underlying_type(&self) -> Self::Underlying {
-        self.as_base_type().get_element_type().into_struct_type()
-    }
-}
-
-impl<'ctx> From<ListType<'ctx>> for PointerType<'ctx> {
-    fn from(value: ListType<'ctx>) -> Self {
-        value.as_base_type()
-    }
-}
-
-/// Proxy type for accessing a `list` value in LLVM.
-#[derive(Copy, Clone)]
-pub struct ListValue<'ctx> {
-    value: PointerValue<'ctx>,
-    llvm_usize: IntType<'ctx>,
-    name: Option<&'ctx str>,
-}
-
-impl<'ctx> ListValue<'ctx> {
-    /// Checks whether `value` is an instance of `list`, returning [Err] if `value` is not an
-    /// instance.
-    pub fn is_instance(value: PointerValue<'ctx>, llvm_usize: IntType<'ctx>) -> Result<(), String> {
-        ListType::is_type(value.get_type(), llvm_usize)
-    }
-
-    /// Creates an [`ListValue`] from a [`PointerValue`].
-    #[must_use]
-    pub fn from_ptr_val(
-        ptr: PointerValue<'ctx>,
-        llvm_usize: IntType<'ctx>,
-        name: Option<&'ctx str>,
-    ) -> Self {
-        debug_assert!(Self::is_instance(ptr, llvm_usize).is_ok());
-
-        <Self as ProxyValue<'ctx>>::Type::from_type(ptr.get_type(), llvm_usize)
-            .create_value(ptr, name)
-    }
-
-    /// Returns the double-indirection pointer to the `data` array, as if by calling `getelementptr`
-    /// on the field.
-    fn pptr_to_data(&self, ctx: &CodeGenContext<'ctx, '_>) -> PointerValue<'ctx> {
-        let llvm_i32 = ctx.ctx.i32_type();
-        let var_name = self.name.map(|v| format!("{v}.data.addr")).unwrap_or_default();
-
-        unsafe {
-            ctx.builder
-                .build_in_bounds_gep(
-                    self.as_base_value(),
-                    &[llvm_i32.const_zero(), llvm_i32.const_zero()],
-                    var_name.as_str(),
-                )
-                .unwrap()
-        }
-    }
-
-    /// Returns the pointer to the field storing the size of this `list`.
-    fn ptr_to_size(&self, ctx: &CodeGenContext<'ctx, '_>) -> PointerValue<'ctx> {
-        let llvm_i32 = ctx.ctx.i32_type();
-        let var_name = self.name.map(|v| format!("{v}.size.addr")).unwrap_or_default();
-
-        unsafe {
-            ctx.builder
-                .build_in_bounds_gep(
-                    self.as_base_value(),
-                    &[llvm_i32.const_zero(), llvm_i32.const_int(1, true)],
-                    var_name.as_str(),
-                )
-                .unwrap()
-        }
-    }
-
-    /// Stores the array of data elements `data` into this instance.
-    fn store_data(&self, ctx: &CodeGenContext<'ctx, '_>, data: PointerValue<'ctx>) {
-        ctx.builder.build_store(self.pptr_to_data(ctx), data).unwrap();
-    }
-
-    /// Convenience method for creating a new array storing data elements with the given element
-    /// type `elem_ty` and `size`.
-    ///
-    /// If `size` is [None], the size stored in the field of this instance is used instead.
-    pub fn create_data(
-        &self,
-        ctx: &mut CodeGenContext<'ctx, '_>,
-        elem_ty: BasicTypeEnum<'ctx>,
-        size: Option<IntValue<'ctx>>,
-    ) {
-        let size = size.unwrap_or_else(|| self.load_size(ctx, None));
-
-        let data = ctx
-            .builder
-            .build_select(
-                ctx.builder
-                    .build_int_compare(IntPredicate::NE, size, self.llvm_usize.const_zero(), "")
-                    .unwrap(),
-                ctx.builder.build_array_alloca(elem_ty, size, "").unwrap(),
-                elem_ty.ptr_type(AddressSpace::default()).const_zero(),
-                "",
-            )
-            .map(BasicValueEnum::into_pointer_value)
-            .unwrap();
-        self.store_data(ctx, data);
-    }
-
-    /// Returns the double-indirection pointer to the `data` array, as if by calling `getelementptr`
-    /// on the field.
-    #[must_use]
-    pub fn data(&self) -> ListDataProxy<'ctx, '_> {
-        ListDataProxy(self)
-    }
-
-    /// Stores the `size` of this `list` into this instance.
-    pub fn store_size<G: CodeGenerator + ?Sized>(
-        &self,
-        ctx: &CodeGenContext<'ctx, '_>,
-        generator: &G,
-        size: IntValue<'ctx>,
-    ) {
-        debug_assert_eq!(size.get_type(), generator.get_size_type(ctx.ctx));
-
-        let psize = self.ptr_to_size(ctx);
-        ctx.builder.build_store(psize, size).unwrap();
-    }
-
-    /// Returns the size of this `list` as a value.
-    pub fn load_size(&self, ctx: &CodeGenContext<'ctx, '_>, name: Option<&str>) -> IntValue<'ctx> {
-        let psize = self.ptr_to_size(ctx);
-        let var_name = name
-            .map(ToString::to_string)
-            .or_else(|| self.name.map(|v| format!("{v}.size")))
-            .unwrap_or_default();
-
-        ctx.builder
-            .build_load(psize, var_name.as_str())
-            .map(BasicValueEnum::into_int_value)
-            .unwrap()
-    }
-}
-
-impl<'ctx> ProxyValue<'ctx> for ListValue<'ctx> {
-    type Base = PointerValue<'ctx>;
-    type Underlying = StructValue<'ctx>;
-    type Type = ListType<'ctx>;
-
-    fn get_type(&self) -> Self::Type {
-        ListType::from_type(self.as_base_value().get_type(), self.llvm_usize)
-    }
-
-    fn as_base_value(&self) -> Self::Base {
-        self.value
-    }
-
-    fn as_underlying_value(
-        &self,
-        ctx: &mut CodeGenContext<'ctx, '_>,
-        name: Option<&'ctx str>,
-    ) -> Self::Underlying {
-        ctx.builder
-            .build_load(self.as_base_value(), name.unwrap_or_default())
-            .map(BasicValueEnum::into_struct_value)
-            .unwrap()
-    }
-}
-
-impl<'ctx> From<ListValue<'ctx>> for PointerValue<'ctx> {
-    fn from(value: ListValue<'ctx>) -> Self {
-        value.as_base_value()
-    }
-}
-
-/// Proxy type for accessing the `data` array of an `list` instance in LLVM.
-#[derive(Copy, Clone)]
-pub struct ListDataProxy<'ctx, 'a>(&'a ListValue<'ctx>);
-
-impl<'ctx> ArrayLikeValue<'ctx> for ListDataProxy<'ctx, '_> {
-    fn element_type<G: CodeGenerator + ?Sized>(
-        &self,
-        _: &CodeGenContext<'ctx, '_>,
-        _: &G,
-    ) -> AnyTypeEnum<'ctx> {
-        self.0.value.get_type().get_element_type()
-    }
-
-    fn base_ptr<G: CodeGenerator + ?Sized>(
-        &self,
-        ctx: &CodeGenContext<'ctx, '_>,
-        _: &G,
-    ) -> PointerValue<'ctx> {
-        let var_name = self.0.name.map(|v| format!("{v}.data")).unwrap_or_default();
-
-        ctx.builder
-            .build_load(self.0.pptr_to_data(ctx), var_name.as_str())
-            .map(BasicValueEnum::into_pointer_value)
-            .unwrap()
-    }
-
-    fn size<G: CodeGenerator + ?Sized>(
-        &self,
-        ctx: &CodeGenContext<'ctx, '_>,
-        _: &G,
-    ) -> IntValue<'ctx> {
-        self.0.load_size(ctx, None)
-    }
-}
-
-impl<'ctx> ArrayLikeIndexer<'ctx> for ListDataProxy<'ctx, '_> {
-    unsafe fn ptr_offset_unchecked<G: CodeGenerator + ?Sized>(
-        &self,
-        ctx: &mut CodeGenContext<'ctx, '_>,
-        generator: &mut G,
-        idx: &IntValue<'ctx>,
-        name: Option<&str>,
-    ) -> PointerValue<'ctx> {
-        let var_name = name.map(|v| format!("{v}.addr")).unwrap_or_default();
-
-        unsafe {
-            ctx.builder
-                .build_in_bounds_gep(self.base_ptr(ctx, generator), &[*idx], var_name.as_str())
-                .unwrap()
-        }
-    }
-
-    fn ptr_offset<G: CodeGenerator + ?Sized>(
-        &self,
-        ctx: &mut CodeGenContext<'ctx, '_>,
-        generator: &mut G,
-        idx: &IntValue<'ctx>,
-        name: Option<&str>,
-    ) -> PointerValue<'ctx> {
-        debug_assert_eq!(idx.get_type(), generator.get_size_type(ctx.ctx));
-
-        let size = self.size(ctx, generator);
-        let in_range = ctx.builder.build_int_compare(IntPredicate::ULT, *idx, size, "").unwrap();
-        ctx.make_assert(
-            generator,
-            in_range,
-            "0:IndexError",
-            "list index out of range",
-            [None, None, None],
-            ctx.current_loc,
-        );
-
-        unsafe { self.ptr_offset_unchecked(ctx, generator, idx, name) }
-    }
-}
-
-impl<'ctx> UntypedArrayLikeAccessor<'ctx> for ListDataProxy<'ctx, '_> {}
-impl<'ctx> UntypedArrayLikeMutator<'ctx> for ListDataProxy<'ctx, '_> {}

nac3core/src/codegen/expr.rs

@@ -1,18 +1,17 @@
 use crate::{
     codegen::{
-        classes::{
-            ArrayLikeIndexer, ArrayLikeValue, ListType, ListValue, ProxyType, ProxyValue,
-            UntypedArrayLikeAccessor,
-        },
         concrete_type::{ConcreteFuncArg, ConcreteTypeEnum, ConcreteTypeStore},
         gen_in_range_check, get_llvm_abi_type, get_llvm_type, get_va_count_arg_name,
         irrt::*,
         llvm_intrinsics::{
             call_expect, call_float_floor, call_float_pow, call_float_powi, call_int_smax,
-            call_int_umin, call_memcpy_generic,
+            call_int_umin,
         },
         need_sret,
-        object::ndarray::{NDArrayOut, ScalarOrNDArray},
+        object::{
+            list::List,
+            ndarray::{NDArrayOut, ScalarOrNDArray},
+        },
         stmt::{
             gen_for_callback_incrementing, gen_if_callback, gen_if_else_expr_callback, gen_raise,
             gen_var,
@@ -38,16 +37,17 @@ use inkwell::{
 use itertools::{chain, izip, Either, Itertools};
 use nac3parser::ast::{
     self, Boolop, Cmpop, Comprehension, Constant, Expr, ExprKind, Location, Operator, StrRef,
-    Unaryop,
 };
 use std::cmp::min;
 use std::iter::{repeat, repeat_with};
 use std::{collections::HashMap, convert::TryInto, iter::once, iter::zip};
+use util::gen_for_model;
 
 use super::{
     model::*,
     object::{
         any::AnyObject,
+        list::ListObject,
         ndarray::{indexing::util::gen_ndarray_subscript_ndindices, NDArrayObject},
         range::RangeObject,
     },
@@ -1081,33 +1081,6 @@ pub fn gen_call<'ctx, G: CodeGenerator>(
     Ok(ctx.build_call_or_invoke(fun_val, &param_vals, "call"))
 }
 
-/// Allocates a List structure with the given [type][ty] and [length]. The name of the resulting
-/// LLVM value is `{name}.addr`, or `list.addr` if [name] is not specified.
-///
-/// Setting `ty` to [`None`] implies that the list is empty **and** does not have a known element
-/// type, and will therefore set the `list.data` type as `size_t*`. It is undefined behavior to
-/// generate a sized list with an unknown element type.
-pub fn allocate_list<'ctx, G: CodeGenerator + ?Sized>(
-    generator: &mut G,
-    ctx: &mut CodeGenContext<'ctx, '_>,
-    ty: Option<BasicTypeEnum<'ctx>>,
-    length: IntValue<'ctx>,
-    name: Option<&'ctx str>,
-) -> ListValue<'ctx> {
-    let llvm_usize = generator.get_size_type(ctx.ctx);
-    let llvm_elem_ty = ty.unwrap_or(llvm_usize.into());
-
-    // List structure; type { ty*, size_t }
-    let arr_ty = ListType::new(generator, ctx.ctx, llvm_elem_ty);
-    let list = arr_ty.new_value(generator, ctx, name);
-
-    let length = ctx.builder.build_int_z_extend(length, llvm_usize, "").unwrap();
-    list.store_size(ctx, generator, length);
-    list.create_data(ctx, llvm_elem_ty, None);
-
-    list
-}
-
 /// Generates LLVM IR for a [list comprehension expression][expr].
 pub fn gen_comprehension<'ctx, G: CodeGenerator>(
     generator: &mut G,
@@ -1148,8 +1121,10 @@ pub fn gen_comprehension<'ctx, G: CodeGenerator>(
     let index = generator.gen_var_alloc(ctx, size_t.into(), Some("index.addr"))?;
     ctx.builder.build_store(index, zero_size_t).unwrap();
 
-    let elem_ty = ctx.get_llvm_type(generator, elt.custom.unwrap());
-    let list;
+    let elem_ty = elt.custom.unwrap();
+    let elem_ty_llvm = ctx.get_llvm_type(generator, elem_ty);
+
+    let list: ListObject<'ctx>;
 
     match &*ctx.unifier.get_ty(iter_ty) {
         TypeEnum::TObj { obj_id, .. }
@@ -1184,14 +1159,11 @@ pub fn gen_comprehension<'ctx, G: CodeGenerator>(
                     zero_size_t,
                     "listcomp.alloc_size",
                 )
-                .unwrap();
-            list = allocate_list(
-                generator,
-                ctx,
-                Some(elem_ty),
-                list_alloc_size.into_int_value(),
-                Some("listcomp.addr"),
-            );
+                .unwrap()
+                .into_int_value();
+
+            let list_alloc_size = Int(SizeT).believe_value(list_alloc_size);
+            list = ListObject::alloca(generator, ctx, elem_ty, list_alloc_size);
 
             let i = generator.gen_store_target(ctx, target, Some("i.addr"))?.unwrap();
             ctx.builder
@@ -1230,14 +1202,12 @@ pub fn gen_comprehension<'ctx, G: CodeGenerator>(
         TypeEnum::TObj { obj_id, .. }
             if *obj_id == ctx.primitives.list.obj_id(&ctx.unifier).unwrap() =>
         {
-            let length = ctx
-                .build_gep_and_load(
-                    iter_val.into_pointer_value(),
-                    &[zero_size_t, int32.const_int(1, false)],
-                    Some("length"),
-                )
-                .into_int_value();
-            list = allocate_list(generator, ctx, Some(elem_ty), length, Some("listcomp"));
+            let source_list = AnyObject { ty: iter_ty, value: iter_val };
+            let source_list = ListObject::from_object(generator, ctx, source_list);
+
+            let len = source_list.instance.get(generator, ctx, |f| f.len);
+
+            list = ListObject::alloca(generator, ctx, elem_ty, len);
 
             let counter = generator.gen_var_alloc(ctx, size_t.into(), Some("counter.addr"))?;
             // counter = -1
@@ -1249,7 +1219,8 @@ pub fn gen_comprehension<'ctx, G: CodeGenerator>(
                 ctx.builder.build_load(counter, "i").map(BasicValueEnum::into_int_value).unwrap();
             let tmp = ctx.builder.build_int_add(tmp, size_t.const_int(1, false), "inc").unwrap();
             ctx.builder.build_store(counter, tmp).unwrap();
-            let cmp = ctx.builder.build_int_compare(IntPredicate::SLT, tmp, length, "cmp").unwrap();
+            let cmp =
+                ctx.builder.build_int_compare(IntPredicate::SLT, tmp, len.value, "cmp").unwrap();
             ctx.builder.build_conditional_branch(cmp, body_bb, cont_bb).unwrap();
 
             ctx.builder.position_at_end(body_bb);
@@ -1272,15 +1243,16 @@ pub fn gen_comprehension<'ctx, G: CodeGenerator>(
     }
 
     // Emits the content of `cont_bb`
-    let emit_cont_bb =
-        |ctx: &CodeGenContext<'ctx, '_>, generator: &dyn CodeGenerator, list: ListValue<'ctx>| {
-            ctx.builder.position_at_end(cont_bb);
-            list.store_size(
-                ctx,
-                generator,
-                ctx.builder.build_load(index, "index").map(BasicValueEnum::into_int_value).unwrap(),
-            );
-        };
+    let emit_cont_bb = |ctx: &mut CodeGenContext<'ctx, '_>,
+                        generator: &mut dyn CodeGenerator,
+                        list: ListObject<'ctx>| {
+        ctx.builder.position_at_end(cont_bb);
+
+        let index = ctx.builder.build_load(index, "index").unwrap();
+        let index = Int(SizeT).check_value(generator, ctx.ctx, index).unwrap();
+
+        list.instance.set(ctx, |f| f.len, index);
+    };
 
     for cond in ifs {
         let result = if let Some(v) = generator.gen_expr(ctx, cond)? {
@@ -1306,10 +1278,13 @@ pub fn gen_comprehension<'ctx, G: CodeGenerator>(
         return Ok(None);
     };
     let i = ctx.builder.build_load(index, "i").map(BasicValueEnum::into_int_value).unwrap();
-    let elem_ptr =
-        unsafe { list.data().ptr_offset_unchecked(ctx, generator, &i, Some("elem_ptr")) };
-    let val = elem.to_basic_value_enum(ctx, generator, elt.custom.unwrap())?;
-    ctx.builder.build_store(elem_ptr, val).unwrap();
+
+    let elem_ptr = list.instance.get(generator, ctx, |f| f.items).offset(ctx, i);
+
+    let elem = elem.to_basic_value_enum(ctx, generator, elt.custom.unwrap())?;
+    let elem = Any(elem_ty_llvm).check_value(generator, ctx.ctx, elem).unwrap();
+    elem_ptr.store(ctx, elem);
+
     ctx.builder
         .build_store(
             index,
@@ -1320,7 +1295,7 @@ pub fn gen_comprehension<'ctx, G: CodeGenerator>(
 
     emit_cont_bb(ctx, generator, list);
 
-    Ok(Some(list.as_base_value().into()))
+    Ok(Some(list.instance.value.into()))
 }
 
 /// Generates LLVM IR for a binary operator expression using the [`Type`] and
@@ -1375,167 +1350,87 @@ pub fn gen_binop_expr_with_values<'ctx, G: CodeGenerator>(
                 debug_assert_eq!(ty1.obj_id(&ctx.unifier), Some(PrimDef::List.id()));
                 debug_assert_eq!(ty2.obj_id(&ctx.unifier), Some(PrimDef::List.id()));
 
-                let elem_ty1 =
-                    if let TypeEnum::TObj { params, .. } = &*ctx.unifier.get_ty_immutable(ty1) {
-                        ctx.unifier.get_representative(*params.iter().next().unwrap().1)
-                    } else {
-                        unreachable!()
-                    };
-                let elem_ty2 =
-                    if let TypeEnum::TObj { params, .. } = &*ctx.unifier.get_ty_immutable(ty2) {
-                        ctx.unifier.get_representative(*params.iter().next().unwrap().1)
-                    } else {
-                        unreachable!()
-                    };
-                debug_assert!(ctx.unifier.unioned(elem_ty1, elem_ty2));
+                let lhs = AnyObject { ty: ty1, value: left_val };
+                let lhs = ListObject::from_object(generator, ctx, lhs);
 
-                let llvm_elem_ty = ctx.get_llvm_type(generator, elem_ty1);
-                let sizeof_elem = llvm_elem_ty.size_of().unwrap();
+                let rhs = AnyObject { ty: ty2, value: right_val };
+                let rhs = ListObject::from_object(generator, ctx, rhs);
 
-                let lhs = ListValue::from_ptr_val(left_val.into_pointer_value(), llvm_usize, None);
-                let rhs = ListValue::from_ptr_val(right_val.into_pointer_value(), llvm_usize, None);
+                debug_assert!(ctx.unifier.unioned(lhs.item_type, rhs.item_type));
+                let common_item_type = lhs.item_type;
 
-                let size = ctx
-                    .builder
-                    .build_int_add(lhs.load_size(ctx, None), rhs.load_size(ctx, None), "")
-                    .unwrap();
+                let lhs_len = lhs.instance.get(generator, ctx, |f| f.len);
+                let rhs_len = rhs.instance.get(generator, ctx, |f| f.len);
 
-                let new_list = allocate_list(generator, ctx, Some(llvm_elem_ty), size, None);
+                let concat_len = lhs_len.add(ctx, rhs_len);
+                let concat = ListObject::alloca(generator, ctx, common_item_type, concat_len);
 
-                let lhs_size = ctx
-                    .builder
-                    .build_int_z_extend_or_bit_cast(
-                        lhs.load_size(ctx, None),
-                        sizeof_elem.get_type(),
-                        "",
-                    )
-                    .unwrap();
-                let lhs_len = ctx.builder.build_int_mul(lhs_size, sizeof_elem, "").unwrap();
+                let lhs_items = lhs.instance.get(generator, ctx, |f| f.items);
+                let rhs_items = rhs.instance.get(generator, ctx, |f| f.items);
+                let concat_items = concat.instance.get(generator, ctx, |f| f.items);
 
-                let rhs_size = ctx
-                    .builder
-                    .build_int_z_extend_or_bit_cast(
-                        rhs.load_size(ctx, None),
-                        sizeof_elem.get_type(),
-                        "",
-                    )
-                    .unwrap();
-                let rhs_len = ctx.builder.build_int_mul(rhs_size, sizeof_elem, "").unwrap();
+                // Copy lhs
+                concat_items.copy_from(generator, ctx, lhs_items, lhs_len.value);
 
-                let list_ptr = new_list.data().base_ptr(ctx, generator);
-                call_memcpy_generic(
+                // Copy rhs
+                concat_items.offset(ctx, lhs_len.value).copy_from(
+                    generator,
                     ctx,
-                    list_ptr,
-                    lhs.data().base_ptr(ctx, generator),
-                    lhs_len,
-                    ctx.ctx.bool_type().const_zero(),
+                    rhs_items,
+                    rhs_len.value,
                 );
 
-                let list_ptr = unsafe {
-                    new_list.data().ptr_offset_unchecked(
-                        ctx,
-                        generator,
-                        &lhs.load_size(ctx, None),
-                        None,
-                    )
-                };
-                call_memcpy_generic(
-                    ctx,
-                    list_ptr,
-                    rhs.data().base_ptr(ctx, generator),
-                    rhs_len,
-                    ctx.ctx.bool_type().const_zero(),
-                );
-
-                Ok(Some(new_list.as_base_value().into()))
+                Ok(Some(concat.instance.value.as_basic_value_enum().into()))
             }
 
             Operator::Mult => {
-                let (elem_ty, list_val, int_val) =
-                    if ty1.obj_id(&ctx.unifier).is_some_and(|id| id == PrimDef::List.id()) {
-                        let elem_ty = if let TypeEnum::TObj { params, .. } =
-                            &*ctx.unifier.get_ty_immutable(ty1)
-                        {
-                            *params.iter().next().unwrap().1
-                        } else {
-                            unreachable!()
-                        };
+                let (list, int) = if ty1
+                    .obj_id(&ctx.unifier)
+                    .is_some_and(|id| id == PrimDef::List.id())
+                {
+                    // Handle `[1, 2, 3] * int`
+                    let list = AnyObject { ty: ty1, value: left_val };
+                    let list = ListObject::from_object(generator, ctx, list);
 
-                        (elem_ty, left_val, right_val)
-                    } else if ty2.obj_id(&ctx.unifier).is_some_and(|id| id == PrimDef::List.id()) {
-                        let elem_ty = if let TypeEnum::TObj { params, .. } =
-                            &*ctx.unifier.get_ty_immutable(ty2)
-                        {
-                            *params.iter().next().unwrap().1
-                        } else {
-                            unreachable!()
-                        };
+                    let int =
+                        Int(SizeT).s_extend_or_bit_cast(generator, ctx, right_val.into_int_value());
+                    (list, int)
+                } else if ty2.obj_id(&ctx.unifier).is_some_and(|id| id == PrimDef::List.id()) {
+                    // Handle `int * [1, 2, 3]`
 
-                        (elem_ty, right_val, left_val)
-                    } else {
-                        unreachable!()
-                    };
-                let list_val =
-                    ListValue::from_ptr_val(list_val.into_pointer_value(), llvm_usize, None);
-                let int_val = ctx
-                    .builder
-                    .build_int_s_extend(int_val.into_int_value(), llvm_usize, "")
-                    .unwrap();
-                // [...] * (i where i < 0) => []
-                let int_val = call_int_smax(ctx, int_val, llvm_usize.const_zero(), None);
+                    let list = AnyObject { ty: ty2, value: right_val };
+                    let list = ListObject::from_object(generator, ctx, list);
 
-                let elem_llvm_ty = ctx.get_llvm_type(generator, elem_ty);
-                let sizeof_elem = elem_llvm_ty.size_of().unwrap();
+                    let int =
+                        Int(SizeT).s_extend_or_bit_cast(generator, ctx, left_val.into_int_value());
+                    (list, int)
+                } else {
+                    unreachable!()
+                };
 
-                let new_list = allocate_list(
-                    generator,
-                    ctx,
-                    Some(elem_llvm_ty),
-                    ctx.builder.build_int_mul(list_val.load_size(ctx, None), int_val, "").unwrap(),
-                    None,
-                );
+                // [...] * (i where i <= 0) => []
+                let int = call_int_smax(ctx, int.value, llvm_usize.const_zero(), None);
+                let int = Int(SizeT).check_value(generator, ctx.ctx, int).unwrap();
 
-                gen_for_callback_incrementing(
-                    generator,
-                    ctx,
-                    None,
-                    llvm_usize.const_zero(),
-                    (int_val, false),
-                    |generator, ctx, _, i| {
-                        let offset = ctx
-                            .builder
-                            .build_int_mul(i, list_val.load_size(ctx, None), "")
-                            .unwrap();
-                        let ptr = unsafe {
-                            new_list.data().ptr_offset_unchecked(ctx, generator, &offset, None)
-                        };
+                let list_items = list.instance.get(generator, ctx, |f| f.items);
+                let list_len = list.instance.get(generator, ctx, |f| f.len);
 
-                        let list_size = ctx
-                            .builder
-                            .build_int_z_extend_or_bit_cast(
-                                list_val.load_size(ctx, None),
-                                sizeof_elem.get_type(),
-                                "",
-                            )
-                            .unwrap();
+                let new_list_len = int.mul(ctx, list_len);
+                let new_list = ListObject::alloca(generator, ctx, list.item_type, new_list_len);
+                let new_list_items = new_list.instance.get(generator, ctx, |f| f.items);
 
-                        let memcpy_sz =
-                            ctx.builder.build_int_mul(list_size, sizeof_elem, "").unwrap();
+                let num_0 = Int(SizeT).const_int(generator, ctx.ctx, 0);
+                let num_1 = Int(SizeT).const_int(generator, ctx.ctx, 1);
+                gen_for_model(generator, ctx, num_0, int, num_1, |generator, ctx, _hooks, i| {
+                    let offset = list_len.mul(ctx, i);
+                    let ptr = new_list_items.offset(ctx, offset.value);
 
-                        call_memcpy_generic(
-                            ctx,
-                            ptr,
-                            list_val.data().base_ptr(ctx, generator),
-                            memcpy_sz,
-                            ctx.ctx.bool_type().const_zero(),
-                        );
+                    ptr.copy_from(generator, ctx, list_items, list_len.value);
+                    Ok(())
+                })
+                .unwrap();
 
-                        Ok(())
-                    },
-                    llvm_usize.const_int(1, false),
-                )?;
-
-                Ok(Some(new_list.as_base_value().into()))
+                Ok(Some(new_list.instance.value.into()))
             }
 
             _ => todo!("Operator not supported"),
@@ -2074,8 +1969,6 @@ pub fn gen_cmpop_expr_with_values<'ctx, G: CodeGenerator>(
                 .iter()
                 .any(|ty| ty.obj_id(&ctx.unifier).is_some_and(|id| id == PrimDef::List.id()))
             {
-                let llvm_usize = generator.get_size_type(ctx.ctx);
-
                 let gen_list_cmpop = |generator: &mut G,
                                       ctx: &mut CodeGenContext<'ctx, '_>|
                  -> Result<IntValue<'ctx>, String> {
@@ -2098,145 +1991,109 @@ pub fn gen_cmpop_expr_with_values<'ctx, G: CodeGenerator>(
                         return Ok(generator.bool_to_i8(ctx, gen_bool_const(ctx, false)));
                     }
 
-                    let left_elem_ty = if let TypeEnum::TObj { params, .. } =
-                        &*ctx.unifier.get_ty_immutable(left_ty)
-                    {
-                        *params.iter().next().unwrap().1
-                    } else {
-                        unreachable!()
-                    };
-                    let right_elem_ty = if let TypeEnum::TObj { params, .. } =
-                        &*ctx.unifier.get_ty_immutable(right_ty)
-                    {
-                        *params.iter().next().unwrap().1
-                    } else {
-                        unreachable!()
-                    };
-
-                    if !ctx.unifier.unioned(left_elem_ty, right_elem_ty) {
-                        return Ok(generator.bool_to_i8(ctx, gen_bool_const(ctx, false)));
-                    }
-
                     if ![Cmpop::Eq, Cmpop::NotEq].contains(op) {
                         todo!("Only __eq__ and __ne__ is implemented for lists")
                     }
 
-                    let left_val =
-                        ListValue::from_ptr_val(lhs.into_pointer_value(), llvm_usize, None);
-                    let right_val =
-                        ListValue::from_ptr_val(rhs.into_pointer_value(), llvm_usize, None);
+                    let lhs = AnyObject { ty: left_ty, value: *lhs };
+                    let lhs = ListObject::from_object(generator, ctx, lhs);
 
-                    Ok(gen_if_else_expr_callback(
+                    let rhs = AnyObject { ty: right_ty, value: *rhs };
+                    let rhs = ListObject::from_object(generator, ctx, rhs);
+
+                    let lhs_len = lhs.instance.get(generator, ctx, |f| f.len);
+                    let rhs_len = rhs.instance.get(generator, ctx, |f| f.len);
+
+                    let result = gen_if_else_expr_callback(
                         generator,
                         ctx,
                         |_, ctx| {
-                            Ok(ctx
-                                .builder
-                                .build_int_compare(
-                                    IntPredicate::EQ,
-                                    left_val.load_size(ctx, None),
-                                    right_val.load_size(ctx, None),
-                                    "",
-                                )
-                                .unwrap())
+                            let same_len = lhs_len.compare(ctx, IntPredicate::EQ, rhs_len);
+                            Ok(same_len.value)
                         },
                         |generator, ctx| {
-                            let acc_addr = generator
-                                .gen_var_alloc(ctx, ctx.ctx.bool_type().into(), None)
-                                .unwrap();
-                            ctx.builder
-                                .build_store(acc_addr, ctx.ctx.bool_type().const_all_ones())
-                                .unwrap();
+                            // The list lengths match. Compare their contents.
+                            let common_len = lhs_len;
 
-                            gen_for_callback_incrementing(
-                                generator,
-                                ctx,
-                                None,
-                                llvm_usize.const_zero(),
-                                (left_val.load_size(ctx, None), false),
-                                |generator, ctx, hooks, i| {
-                                    let left = unsafe {
-                                        left_val.data().get_unchecked(ctx, generator, &i, None)
-                                    };
-                                    let right = unsafe {
-                                        right_val.data().get_unchecked(ctx, generator, &i, None)
-                                    };
+                            let bool_false = Int(Bool).const_false(generator, ctx.ctx);
+                            let bool_true = Int(Bool).const_true(generator, ctx.ctx);
 
-                                    let res = gen_cmpop_expr_with_values(
-                                        generator,
-                                        ctx,
-                                        (Some(left_elem_ty), left),
-                                        &[Cmpop::Eq],
-                                        &[(Some(right_elem_ty), right)],
-                                    )?
+                            let list_equal = Int(Bool).alloca(generator, ctx);
+                            list_equal.store(ctx, bool_true);
+
+                            let lhs_items = lhs.instance.get(generator, ctx, |f| f.items);
+                            let rhs_items = rhs.instance.get(generator, ctx, |f| f.items);
+
+                            let num_0 = Int(SizeT).const_int(generator, ctx.ctx, 0);
+                            let num_1 = Int(SizeT).const_int(generator, ctx.ctx, 1);
+                            gen_for_model(generator, ctx, num_0, common_len, num_1, |generator, ctx, hooks, i| {
+                                let lhs_item = lhs_items.get_index(generator, ctx, i.value);
+                                let rhs_item = rhs_items.get_index(generator, ctx, i.value);
+
+                                let equal = gen_cmpop_expr_with_values(
+                                    generator,
+                                    ctx,
+                                    (Some(lhs.item_type), lhs_item.value),
+                                    &[Cmpop::Eq],
+                                    &[(Some(rhs.item_type), rhs_item.value)],
+                                )?
                                     .unwrap()
                                     .to_basic_value_enum(ctx, generator, ctx.primitives.bool)
                                     .unwrap()
                                     .into_int_value();
 
-                                    gen_if_callback(
-                                        generator,
-                                        ctx,
-                                        |_, ctx| {
-                                            Ok(ctx
-                                                .builder
-                                                .build_int_compare(
-                                                    IntPredicate::EQ,
-                                                    res,
-                                                    res.get_type().const_zero(),
-                                                    "",
-                                                )
-                                                .unwrap())
-                                        },
-                                        |_, ctx| {
-                                            ctx.builder
-                                                .build_store(
-                                                    acc_addr,
-                                                    ctx.ctx.bool_type().const_zero(),
-                                                )
-                                                .unwrap();
-                                            ctx.builder
-                                                .build_unconditional_branch(hooks.exit_bb)
-                                                .unwrap();
-
-                                            Ok(())
-                                        },
-                                        |_, _| Ok(()),
+                                // equal is an i8, convert it into a i1 with this.
+                                let equal = ctx
+                                    .builder
+                                    .build_int_compare(
+                                        IntPredicate::NE,
+                                        equal,
+                                        equal.get_type().const_zero(),
+                                        "",
                                     )
                                     .unwrap();
 
-                                    Ok(())
-                                },
-                                llvm_usize.const_int(1, false),
-                            )?;
-
-                            let acc = ctx
-                                .builder
-                                .build_load(acc_addr, "")
-                                .map(BasicValueEnum::into_int_value)
-                                .unwrap();
-                            let acc = if *op == Cmpop::NotEq {
-                                gen_unaryop_expr_with_values(
+                                // if (!equal) { break; }
+                                gen_if_callback(
                                     generator,
                                     ctx,
-                                    Unaryop::Not,
-                                    (&Some(ctx.primitives.bool), acc.into()),
-                                )?
-                                .unwrap()
-                                .to_basic_value_enum(ctx, generator, ctx.primitives.bool)?
-                                .into_int_value()
-                            } else {
-                                acc
+                                    |_generator, _ctx| {
+                                        Ok(equal) },
+                                    |_generator, _ctx| {
+                                        // Items match. Do nothing
+                                        Ok(())
+                                    },
+                                    |_generator, ctx| {
+                                        // Items don't match.
+                                        list_equal.store(ctx, bool_false);
+                                        ctx.builder.build_unconditional_branch(hooks.exit_bb).unwrap();
+                                        Ok(())
+                                    },
+                                )?;
+
+                                Ok(())
+                            })?;
+
+                            let bool_result = match op {
+                                Cmpop::Eq => {
+                                    list_equal.load(generator, ctx)
+                                },
+                                Cmpop::NotEq => {
+                                    list_equal.load(generator, ctx).not(ctx)
+                                },
+                                _ => unreachable!()
                             };
 
-                            Ok(Some(generator.bool_to_i8(ctx, acc)))
+                            Ok(Some(generator.bool_to_i8(ctx, bool_result.value)))
                         },
                         |generator, ctx| {
+                            // The list lengths don't match, return false / true.
                             Ok(Some(generator.bool_to_i8(ctx, gen_bool_const(ctx, false))))
                         },
-                    )?
-                    .map(BasicValueEnum::into_int_value)
-                    .unwrap())
+                    )?.unwrap();
+
+                    let result = result.into_int_value();
+                    Ok(result)
                 };
 
                 gen_list_cmpop(generator, ctx)?
@@ -2436,7 +2293,6 @@ pub fn gen_expr<'ctx, G: CodeGenerator>(
 ) -> Result<Option<ValueEnum<'ctx>>, String> {
     ctx.current_loc = expr.location;
     let int32 = ctx.ctx.i32_type();
-    let usize = generator.get_size_type(ctx.ctx);
     let zero = int32.const_int(0, false);
 
     let loc = ctx.debug_info.0.create_debug_location(
@@ -2520,8 +2376,8 @@ pub fn gen_expr<'ctx, G: CodeGenerator>(
                 return Ok(None);
             }
 
-            let ty = if elements.is_empty() {
-                let ty = if let TypeEnum::TObj { obj_id, params, .. } =
+            let item_ty = if elements.is_empty() {
+                let item_type = if let TypeEnum::TObj { obj_id, params, .. } =
                     &*ctx.unifier.get_ty(expr.custom.unwrap())
                 {
                     assert_eq!(*obj_id, PrimDef::List.id());
@@ -2531,27 +2387,37 @@ pub fn gen_expr<'ctx, G: CodeGenerator>(
                     unreachable!()
                 };
 
-                if let TypeEnum::TVar { .. } = &*ctx.unifier.get_ty_immutable(ty) {
+                if let TypeEnum::TVar { .. } = &*ctx.unifier.get_ty_immutable(item_type) {
+                    // `item_type` is not resolved.
+                    // This could happen when the user wrote a `[]` and the typechecker has no hints about `item_type`.
                     None
                 } else {
-                    Some(ctx.get_llvm_type(generator, ty))
+                    Some(ctx.get_llvm_type(generator, item_type))
                 }
             } else {
                 Some(elements[0].get_type())
             };
-            let length = generator.get_size_type(ctx.ctx).const_int(elements.len() as u64, false);
-            let arr_str_ptr = allocate_list(generator, ctx, ty, length, Some("list"));
-            let arr_ptr = arr_str_ptr.data();
-            for (i, v) in elements.iter().enumerate() {
-                let elem_ptr = arr_ptr.ptr_offset(
-                    ctx,
-                    generator,
-                    &usize.const_int(i as u64, false),
-                    Some("elem_ptr"),
-                );
-                ctx.builder.build_store(elem_ptr, *v).unwrap();
+
+            let list_len = Int(SizeT).const_int(generator, ctx.ctx, elements.len() as u64);
+            let list_item_ty = Any(item_ty.unwrap_or_else(|| {
+                // The list is an empty list with an unresolved item_type.
+
+                // TODO: LLVM 14 requires all pointer types to have a type.
+                // We will use `size_t` as a placeholder for now.
+                generator.get_size_type(ctx.ctx).as_basic_type_enum()
+            }));
+
+            // Allocate list_items and load in the items
+            let list_items = list_item_ty.array_alloca(generator, ctx, list_len.value);
+            for (i, item) in elements.iter().enumerate() {
+                let item = list_item_ty.believe_value(*item);
+                list_items.set_index_const(ctx, i as u64, item);
             }
-            arr_str_ptr.as_base_value().into()
+
+            let list = Struct(List { item: list_item_ty }).alloca(generator, ctx);
+            list.set(ctx, |f| f.items, list_items);
+            list.set(ctx, |f| f.len, list_len);
+            list.value.as_basic_value_enum().into()
         }
         ExprKind::Tuple { elts, .. } => {
             let elements_val = elts
@@ -2957,18 +2823,20 @@ pub fn gen_expr<'ctx, G: CodeGenerator>(
         }
         ExprKind::Subscript { value, slice, .. } => {
             match &*ctx.unifier.get_ty(value.custom.unwrap()) {
-                TypeEnum::TObj { obj_id, params, .. } if *obj_id == PrimDef::List.id() => {
-                    let ty = params.iter().next().unwrap().1;
-
+                TypeEnum::TObj { obj_id, .. } if *obj_id == PrimDef::List.id() => {
                     let v = if let Some(v) = generator.gen_expr(ctx, value)? {
                         v.to_basic_value_enum(ctx, generator, value.custom.unwrap())?
-                            .into_pointer_value()
                     } else {
                         return Ok(None);
                     };
-                    let v = ListValue::from_ptr_val(v, usize, Some("arr"));
-                    let ty = ctx.get_llvm_type(generator, *ty);
+
+                    let list = AnyObject { ty: value.custom.unwrap(), value: v };
+                    let list = ListObject::from_object(generator, ctx, list);
+
+                    let list_len = list.instance.get(generator, ctx, |f| f.len);
+
                     if let ExprKind::Slice { lower, upper, step } = &slice.node {
+                        // Handle `my_list[lower:upper:step]`
                         let one = int32.const_int(1, false);
                         let Some((start, end, step)) = handle_slice_indices(
                             lower,
@@ -2976,7 +2844,7 @@ pub fn gen_expr<'ctx, G: CodeGenerator>(
                             step,
                             ctx,
                             generator,
-                            v.load_size(ctx, None),
+                            list_len.value,
                         )?
                         else {
                             return Ok(None);
@@ -2998,37 +2866,37 @@ pub fn gen_expr<'ctx, G: CodeGenerator>(
                                 .unwrap(),
                             step,
                         );
-                        let res_array_ret =
-                            allocate_list(generator, ctx, Some(ty), length, Some("ret"));
-                        let Some(res_ind) = handle_slice_indices(
-                            &None,
-                            &None,
-                            &None,
-                            ctx,
-                            generator,
-                            res_array_ret.load_size(ctx, None),
-                        )?
+
+                        let sublist_length =
+                            Int(SizeT).s_extend_or_bit_cast(generator, ctx, length);
+                        let sublist =
+                            ListObject::alloca(generator, ctx, list.item_type, sublist_length);
+                        let Some(res_ind) =
+                            handle_slice_indices(&None, &None, &None, ctx, generator, length)?
                         else {
                             return Ok(None);
                         };
+
+                        let list_item_type_llvm = ctx.get_llvm_type(generator, list.item_type);
                         list_slice_assignment(
                             generator,
                             ctx,
-                            ty,
-                            res_array_ret,
+                            list_item_type_llvm,
+                            sublist.instance,
                             res_ind,
-                            v,
+                            list.instance,
                             (start, end, step),
                         );
-                        res_array_ret.as_base_value().into()
+                        sublist.instance.value.as_basic_value_enum().into()
                     } else {
-                        let len = v.load_size(ctx, Some("len"));
+                        // Handle `my_list[i]`
                         let raw_index = if let Some(v) = generator.gen_expr(ctx, slice)? {
                             v.to_basic_value_enum(ctx, generator, slice.custom.unwrap())?
                                 .into_int_value()
                         } else {
                             return Ok(None);
                         };
+
                         let raw_index = ctx
                             .builder
                             .build_int_s_extend(raw_index, generator.get_size_type(ctx.ctx), "sext")
@@ -3043,8 +2911,10 @@ pub fn gen_expr<'ctx, G: CodeGenerator>(
                                 "is_neg",
                             )
                             .unwrap();
-                        let adjusted =
-                            ctx.builder.build_int_add(raw_index, len, "adjusted").unwrap();
+                        let adjusted = ctx
+                            .builder
+                            .build_int_add(raw_index, list_len.value, "adjusted")
+                            .unwrap();
                         let index = ctx
                             .builder
                             .build_select(is_negative, adjusted, raw_index, "index")
@@ -3054,17 +2924,20 @@ pub fn gen_expr<'ctx, G: CodeGenerator>(
                         // bigger than the length (for unsigned cmp)
                         let bound_check = ctx
                             .builder
-                            .build_int_compare(IntPredicate::ULT, index, len, "inbound")
+                            .build_int_compare(IntPredicate::ULT, index, list_len.value, "inbound")
                             .unwrap();
                         ctx.make_assert(
                             generator,
                             bound_check,
                             "0:IndexError",
                             "index {0} out of bounds 0:{1}",
-                            [Some(raw_index), Some(len), None],
+                            [Some(raw_index), Some(list_len.value), None],
                             expr.location,
                         );
-                        v.data().get(ctx, generator, &index, None).into()
+
+                        let list_items = list.instance.get(generator, ctx, |f| f.items);
+                        let item = list_items.get_index(generator, ctx, index);
+                        item.value.into()
                     }
                 }
                 TypeEnum::TObj { obj_id, .. } if *obj_id == PrimDef::NDArray.id() => {

nac3core/src/codegen/irrt/mod.rs

@@ -1,7 +1,6 @@
 use crate::{symbol_resolver::SymbolResolver, typecheck::typedef::Type};
 
 use super::{
-    classes::{ArrayLikeValue, ListValue},
     model::*,
     object::{
         list::List,
@@ -327,12 +326,11 @@ pub fn list_slice_assignment<'ctx, G: CodeGenerator + ?Sized>(
     generator: &mut G,
     ctx: &mut CodeGenContext<'ctx, '_>,
     ty: BasicTypeEnum<'ctx>,
-    dest_arr: ListValue<'ctx>,
+    dest_arr: Instance<'ctx, Ptr<Struct<List<Any<'ctx>>>>>,
     dest_idx: (IntValue<'ctx>, IntValue<'ctx>, IntValue<'ctx>),
-    src_arr: ListValue<'ctx>,
+    src_arr: Instance<'ctx, Ptr<Struct<List<Any<'ctx>>>>>,
     src_idx: (IntValue<'ctx>, IntValue<'ctx>, IntValue<'ctx>),
 ) {
-    let size_ty = generator.get_size_type(ctx.ctx);
     let int8_ptr = ctx.ctx.i8_type().ptr_type(AddressSpace::default());
     let int32 = ctx.ctx.i32_type();
     let (fun_symbol, elem_ptr_type) = ("__nac3_list_slice_assign_var_size", int8_ptr);
@@ -358,16 +356,14 @@ pub fn list_slice_assignment<'ctx, G: CodeGenerator + ?Sized>(
 
     let zero = int32.const_zero();
     let one = int32.const_int(1, false);
-    let dest_arr_ptr = dest_arr.data().base_ptr(ctx, generator);
+
     let dest_arr_ptr =
-        ctx.builder.build_pointer_cast(dest_arr_ptr, elem_ptr_type, "dest_arr_ptr_cast").unwrap();
-    let dest_len = dest_arr.load_size(ctx, Some("dest.len"));
-    let dest_len = ctx.builder.build_int_truncate_or_bit_cast(dest_len, int32, "srclen32").unwrap();
-    let src_arr_ptr = src_arr.data().base_ptr(ctx, generator);
+        dest_arr.get(generator, ctx, |f| f.items).pointer_cast(generator, ctx, Int(Byte)).value;
     let src_arr_ptr =
-        ctx.builder.build_pointer_cast(src_arr_ptr, elem_ptr_type, "src_arr_ptr_cast").unwrap();
-    let src_len = src_arr.load_size(ctx, Some("src.len"));
-    let src_len = ctx.builder.build_int_truncate_or_bit_cast(src_len, int32, "srclen32").unwrap();
+        src_arr.get(generator, ctx, |f| f.items).pointer_cast(generator, ctx, Int(Byte)).value;
+
+    let dest_len = dest_arr.get(generator, ctx, |f| f.len).truncate(generator, ctx, Int32).value;
+    let src_len = src_arr.get(generator, ctx, |f| f.len).truncate(generator, ctx, Int32).value;
 
     // index in bound and positive should be done
     // assert if dest.step == 1 then len(src) <= len(dest) else len(src) == len(dest), and
@@ -463,8 +459,10 @@ pub fn list_slice_assignment<'ctx, G: CodeGenerator + ?Sized>(
     let cont_bb = ctx.ctx.append_basic_block(current, "cont");
     ctx.builder.build_conditional_branch(need_update, update_bb, cont_bb).unwrap();
     ctx.builder.position_at_end(update_bb);
-    let new_len = ctx.builder.build_int_z_extend_or_bit_cast(new_len, size_ty, "new_len").unwrap();
-    dest_arr.store_size(ctx, generator, new_len);
+
+    let new_len = Int(SizeT).z_extend_or_bit_cast(generator, ctx, new_len);
+    dest_arr.set(ctx, |f| f.len, new_len);
+
     ctx.builder.build_unconditional_branch(cont_bb).unwrap();
     ctx.builder.position_at_end(cont_bb);
 }

nac3core/src/codegen/mod.rs

@@ -1,5 +1,4 @@
 use crate::{
-    codegen::classes::{ListType, ProxyType},
     symbol_resolver::{StaticValue, SymbolResolver},
     toplevel::{helper::PrimDef, TopLevelContext, TopLevelDef},
     typecheck::{
@@ -26,7 +25,7 @@ use inkwell::{
 use itertools::Itertools;
 use model::*;
 use nac3parser::ast::{Location, Stmt, StrRef};
-use object::{ndarray::NDArray, range::Range};
+use object::{list::List, ndarray::NDArray, range::Range};
 use parking_lot::{Condvar, Mutex};
 use std::collections::{HashMap, HashSet};
 use std::sync::{
@@ -488,8 +487,8 @@ fn get_llvm_type<'ctx, G: CodeGenerator + ?Sized>(
                                 type_cache,
                                 *params.iter().next().unwrap().1,
                             );
-
-                            ListType::new(generator, ctx, element_type).as_base_type().into()
+                            let item = Any(element_type);
+                            Ptr(Struct(List { item })).get_type(generator, ctx).as_basic_type_enum()
                         }
 
                         TObj { obj_id, .. } if *obj_id == PrimDef::NDArray.id() => {

nac3core/src/codegen/model/int.rs

@@ -340,4 +340,10 @@ impl<'ctx, N: IntKind<'ctx>> Instance<'ctx, Int<N>> {
         let value = ctx.builder.build_int_compare(op, self.value, other.value, "").unwrap();
         Int(Bool).believe_value(value)
     }
+
+    #[must_use]
+    pub fn not(&self, ctx: &CodeGenContext<'ctx, '_>) -> Self {
+        let value = ctx.builder.build_not(self.value, "").unwrap();
+        self.model.believe_value(value)
+    }
 }

nac3core/src/codegen/model/ptr.rs

@@ -175,8 +175,16 @@ impl<'ctx, Item: Model<'ctx>> Instance<'ctx, Ptr<Item>> {
         source: Self,
         num_items: IntValue<'ctx>,
     ) {
+        let llvm_usize = generator.get_size_type(ctx.ctx);
+
+        // Force extend `num_items` and `itemsize` so their types would match.
         let itemsize = self.model.sizeof(generator, ctx.ctx);
-        let totalsize = ctx.builder.build_int_mul(itemsize, num_items, "totalsize").unwrap(); // TODO: Int types may not match.
+        let itemsize =
+            ctx.builder.build_int_z_extend_or_bit_cast(itemsize, llvm_usize, "").unwrap();
+        let num_items =
+            ctx.builder.build_int_z_extend_or_bit_cast(num_items, llvm_usize, "").unwrap();
+
+        let totalsize = ctx.builder.build_int_mul(itemsize, num_items, "totalsize").unwrap();
 
         let is_volatile = ctx.ctx.bool_type().const_zero(); // is_volatile = false
         call_memcpy_generic(ctx, self.value, source.value, totalsize, is_volatile);

nac3core/src/codegen/object/list.rs

@@ -1,3 +1,5 @@
+use inkwell::types::BasicType;
+
 use crate::{
     codegen::{model::*, CodeGenContext, CodeGenerator},
     typecheck::typedef::{iter_type_vars, Type, TypeEnum},
@@ -25,7 +27,7 @@ impl<'ctx, Item: Model<'ctx>> StructKind<'ctx> for List<Item> {
 
     fn traverse_fields<F: FieldTraversal<'ctx>>(&self, traversal: &mut F) -> Self::Fields<F> {
         Self::Fields {
-            items: traversal.add("data", Ptr(self.item)),
+            items: traversal.add("items", Ptr(self.item)),
             len: traversal.add_auto("len"),
         }
     }
@@ -34,7 +36,8 @@ impl<'ctx, Item: Model<'ctx>> StructKind<'ctx> for List<Item> {
 /// A NAC3 Python List object.
 #[derive(Debug, Clone, Copy)]
 pub struct ListObject<'ctx> {
-    /// Typechecker type of the list items
+    /// Typechecker type of the list items. Could be [`TypeEnum::TVar`] if unresolved (like
+    /// in the case of empty lists and the typechecker does not have enough hints).
     pub item_type: Type,
     pub instance: Instance<'ctx, Ptr<Struct<List<Any<'ctx>>>>>,
 }
@@ -63,7 +66,15 @@ impl<'ctx> ListObject<'ctx> {
             }
         };
 
-        let plist = Ptr(Struct(List { item: Any(ctx.get_llvm_type(generator, item_type)) }));
+        // If `item_type` is unresolved, the list's ptr will default to `size_t*`
+        // as a placeholder because there are no opaque pointers in LLVM 14.
+        let item_type_llvm = if let TypeEnum::TVar { .. } = &*ctx.unifier.get_ty(item_type) {
+            generator.get_size_type(ctx.ctx).as_basic_type_enum()
+        } else {
+            ctx.get_llvm_type(generator, item_type)
+        };
+
+        let plist = Ptr(Struct(List { item: Any(item_type_llvm) }));
 
         // Create object
         let value = plist.check_value(generator, ctx.ctx, object.value).unwrap();
@@ -91,7 +102,7 @@ impl<'ctx> ListObject<'ctx> {
     /// Get the value of this [`ListObject`] as a list with opaque items.
     ///
     /// This function allocates on the stack to create the list, but the
-    /// reference to the `items` are preserved.
+    /// reference to the `items` is preserved.
     pub fn get_opaque_list_ptr<G: CodeGenerator + ?Sized>(
         &self,
         generator: &mut G,
@@ -109,4 +120,31 @@ impl<'ctx> ListObject<'ctx> {
 
         opaque_list
     }
+
+    /// Allocate a list on the stack given its `item_type` and `len`.
+    ///
+    /// The returned list's content will be:
+    /// - `items`: allocated with an array of length `len` with uninitialized values.
+    /// - `len`: set to `len`.
+    pub fn alloca<G: CodeGenerator + ?Sized>(
+        generator: &mut G,
+        ctx: &mut CodeGenContext<'ctx, '_>,
+        item_type: Type,
+        len: Instance<'ctx, Int<SizeT>>,
+    ) -> Self {
+        // If `item_type` is unresolved, the list's ptr will default to `size_t*`
+        // as a placeholder because there are no opaque pointers in LLVM 14.
+        let item_type_llvm = if let TypeEnum::TVar { .. } = &*ctx.unifier.get_ty(item_type) {
+            generator.get_size_type(ctx.ctx).as_basic_type_enum()
+        } else {
+            ctx.get_llvm_type(generator, item_type)
+        };
+        let items = Any(item_type_llvm).array_alloca(generator, ctx, len.value);
+
+        let instance = Struct(List { item: Any(item_type_llvm) }).alloca(generator, ctx);
+        instance.set(ctx, |f| f.items, items);
+        instance.set(ctx, |f| f.len, len);
+
+        ListObject { item_type, instance }
+    }
 }

nac3core/src/codegen/stmt.rs

@@ -3,6 +3,7 @@ use super::{
     irrt::{handle_slice_indices, list_slice_assignment},
     object::{
         any::AnyObject,
+        list::ListObject,
         ndarray::{
             indexing::util::gen_ndarray_subscript_ndindices, NDArrayObject, ScalarOrNDArray,
         },
@@ -11,11 +12,7 @@ use super::{
     CodeGenContext, CodeGenerator,
 };
 use crate::{
-    codegen::{
-        classes::{ArrayLikeIndexer, ArraySliceValue, ListValue},
-        expr::gen_binop_expr,
-        gen_in_range_check,
-    },
+    codegen::{classes::ArraySliceValue, expr::gen_binop_expr, gen_in_range_check, model::*},
     toplevel::{DefinitionId, TopLevelDef},
     typecheck::{
         magic_methods::Binop,
@@ -296,63 +293,56 @@ pub fn gen_setitem<'ctx, G: CodeGenerator>(
     let key_ty = key.custom.unwrap();
 
     match &*ctx.unifier.get_ty(target_ty) {
-        TypeEnum::TObj { obj_id, params: list_params, .. }
+        TypeEnum::TObj { obj_id, .. }
             if *obj_id == ctx.primitives.list.obj_id(&ctx.unifier).unwrap() =>
         {
             // Handle list item assignment
-            let llvm_usize = generator.get_size_type(ctx.ctx);
-            let target_item_ty = iter_type_vars(list_params).next().unwrap().ty;
-
             let target = generator
                 .gen_expr(ctx, target)?
                 .unwrap()
-                .to_basic_value_enum(ctx, generator, target_ty)?
-                .into_pointer_value();
-            let target = ListValue::from_ptr_val(target, llvm_usize, None);
+                .to_basic_value_enum(ctx, generator, target_ty)?;
+
+            let target = AnyObject { ty: target_ty, value: target };
+            let target = ListObject::from_object(generator, ctx, target);
+
+            let target_len = target.instance.get(generator, ctx, |f| f.len);
+            let target_item_type_llvm = ctx.get_llvm_type(generator, target.item_type);
 
             if let ExprKind::Slice { .. } = &key.node {
                 // Handle assigning to a slice
                 let ExprKind::Slice { lower, upper, step } = &key.node else { unreachable!() };
-                let Some((start, end, step)) = handle_slice_indices(
-                    lower,
-                    upper,
-                    step,
-                    ctx,
-                    generator,
-                    target.load_size(ctx, None),
-                )?
+                let Some((start, end, step)) =
+                    handle_slice_indices(lower, upper, step, ctx, generator, target_len.value)?
                 else {
                     return Ok(());
                 };
 
-                let value =
-                    value.to_basic_value_enum(ctx, generator, value_ty)?.into_pointer_value();
-                let value = ListValue::from_ptr_val(value, llvm_usize, None);
+                let value = value.to_basic_value_enum(ctx, generator, value_ty)?;
 
-                let target_item_ty = ctx.get_llvm_type(generator, target_item_ty);
-                let Some(src_ind) = handle_slice_indices(
-                    &None,
-                    &None,
-                    &None,
-                    ctx,
-                    generator,
-                    value.load_size(ctx, None),
-                )?
+                let value = AnyObject { ty: value_ty, value };
+                let value = ListObject::from_object(generator, ctx, value);
+
+                let value_len = value.instance.get(generator, ctx, |f| f.len);
+
+                let Some(src_ind) =
+                    handle_slice_indices(&None, &None, &None, ctx, generator, value_len.value)?
                 else {
                     return Ok(());
                 };
                 list_slice_assignment(
                     generator,
                     ctx,
-                    target_item_ty,
-                    target,
+                    target_item_type_llvm,
+                    target.instance,
                     (start, end, step),
-                    value,
+                    value.instance,
                     src_ind,
                 );
             } else {
                 // Handle assigning to an index
-                let len = target.load_size(ctx, Some("len"));
+                let value = value.to_basic_value_enum(ctx, generator, value_ty)?;
+                let value =
+                    Any(target_item_type_llvm).check_value(generator, ctx.ctx, value).unwrap();
 
                 let index = generator
                     .gen_expr(ctx, key)?
@@ -374,7 +364,8 @@ pub fn gen_setitem<'ctx, G: CodeGenerator>(
                         "is_neg",
                     )
                     .unwrap();
-                let adjusted = ctx.builder.build_int_add(index, len, "adjusted").unwrap();
+                let adjusted =
+                    ctx.builder.build_int_add(index, target_len.value, "adjusted").unwrap();
                 let index = ctx
                     .builder
                     .build_select(is_negative, adjusted, index, "index")
@@ -385,22 +376,23 @@ pub fn gen_setitem<'ctx, G: CodeGenerator>(
                 // bigger than the length (for unsigned cmp)
                 let bound_check = ctx
                     .builder
-                    .build_int_compare(IntPredicate::ULT, index, len, "inbound")
+                    .build_int_compare(IntPredicate::ULT, index, target_len.value, "inbound")
                     .unwrap();
                 ctx.make_assert(
                     generator,
                     bound_check,
                     "0:IndexError",
                     "index {0} out of bounds 0:{1}",
-                    [Some(index), Some(len), None],
+                    [Some(index), Some(target_len.value), None],
                     key.location,
                 );
 
                 // Write value to index on list
-                let item_ptr =
-                    target.data().ptr_offset(ctx, generator, &index, Some("list_item_ptr"));
-                let value = value.to_basic_value_enum(ctx, generator, value_ty)?;
-                ctx.builder.build_store(item_ptr, value).unwrap();
+                target
+                    .instance
+                    .get(generator, ctx, |f| f.items)
+                    .offset(ctx, index)
+                    .store(ctx, value);
             }
         }
         TypeEnum::TObj { obj_id, .. }

nac3core/src/codegen/test.rs

@@ -1,9 +1,7 @@
 use crate::{
     codegen::{
-        classes::{ListType, ProxyType},
-        concrete_type::ConcreteTypeStore,
-        CodeGenContext, CodeGenLLVMOptions, CodeGenTargetMachineOptions, CodeGenTask,
-        CodeGenerator, DefaultCodeGenerator, WithCall, WorkerRegistry,
+        concrete_type::ConcreteTypeStore, CodeGenContext, CodeGenLLVMOptions,
+        CodeGenTargetMachineOptions, CodeGenTask, DefaultCodeGenerator, WithCall, WorkerRegistry,
     },
     symbol_resolver::{SymbolResolver, ValueEnum},
     toplevel::{
@@ -436,15 +434,3 @@ fn test_simple_call() {
     registry.add_task(task);
     registry.wait_tasks_complete(handles);
 }
-
-#[test]
-fn test_classes_list_type_new() {
-    let ctx = inkwell::context::Context::create();
-    let generator = DefaultCodeGenerator::new(String::new(), 64);
-
-    let llvm_i32 = ctx.i32_type();
-    let llvm_usize = generator.get_size_type(&ctx);
-
-    let llvm_list = ListType::new(&generator, &ctx, llvm_i32.into());
-    assert!(ListType::is_type(llvm_list.as_base_type(), llvm_usize).is_ok());
-}