diff --git a/nac3core/src/codegen/generator.rs b/nac3core/src/codegen/generator.rs
index f277ec9a..be007c2a 100644
--- a/nac3core/src/codegen/generator.rs
+++ b/nac3core/src/codegen/generator.rs
@@ -17,6 +17,7 @@ pub trait CodeGenerator {
     /// Return the module name for the code generator.
     fn get_name(&self) -> &str;
 
+    /// Return an instance of [`IntType`] corresponding to the type of `size_t` for this instance.
     fn get_size_type<'ctx>(&self, ctx: &'ctx Context) -> IntType<'ctx>;
 
     /// Generate function call and returns the function return value.
diff --git a/nac3core/src/codegen/irrt/list.rs b/nac3core/src/codegen/irrt/list.rs
index a7fec59d..2c57f8e7 100644
--- a/nac3core/src/codegen/irrt/list.rs
+++ b/nac3core/src/codegen/irrt/list.rs
@@ -24,42 +24,52 @@ pub fn list_slice_assignment<'ctx, G: CodeGenerator + ?Sized>(
     src_arr: ListValue<'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);
+    let llvm_usize = generator.get_size_type(ctx.ctx);
+    let llvm_pi8 = ctx.ctx.i8_type().ptr_type(AddressSpace::default());
+    let llvm_i32 = ctx.ctx.i32_type();
+
+    assert_eq!(dest_idx.0.get_type(), llvm_i32);
+    assert_eq!(dest_idx.1.get_type(), llvm_i32);
+    assert_eq!(dest_idx.2.get_type(), llvm_i32);
+    assert_eq!(src_idx.0.get_type(), llvm_i32);
+    assert_eq!(src_idx.1.get_type(), llvm_i32);
+    assert_eq!(src_idx.2.get_type(), llvm_i32);
+
+    let (fun_symbol, elem_ptr_type) = ("__nac3_list_slice_assign_var_size", llvm_pi8);
     let slice_assign_fun = {
         let ty_vec = vec![
-            int32.into(),         // dest start idx
-            int32.into(),         // dest end idx
-            int32.into(),         // dest step
+            llvm_i32.into(),      // dest start idx
+            llvm_i32.into(),      // dest end idx
+            llvm_i32.into(),      // dest step
             elem_ptr_type.into(), // dest arr ptr
-            int32.into(),         // dest arr len
-            int32.into(),         // src start idx
-            int32.into(),         // src end idx
-            int32.into(),         // src step
+            llvm_i32.into(),      // dest arr len
+            llvm_i32.into(),      // src start idx
+            llvm_i32.into(),      // src end idx
+            llvm_i32.into(),      // src step
             elem_ptr_type.into(), // src arr ptr
-            int32.into(),         // src arr len
-            int32.into(),         // size
+            llvm_i32.into(),      // src arr len
+            llvm_i32.into(),      // size
         ];
         ctx.module.get_function(fun_symbol).unwrap_or_else(|| {
-            let fn_t = int32.fn_type(ty_vec.as_slice(), false);
+            let fn_t = llvm_i32.fn_type(ty_vec.as_slice(), false);
             ctx.module.add_function(fun_symbol, fn_t, None)
         })
     };
 
-    let zero = int32.const_zero();
-    let one = int32.const_int(1, false);
+    let zero = llvm_i32.const_zero();
+    let one = llvm_i32.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 dest_len =
+        ctx.builder.build_int_truncate_or_bit_cast(dest_len, llvm_i32, "srclen32").unwrap();
     let src_arr_ptr = src_arr.data().base_ptr(ctx, generator);
     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();
+    let src_len =
+        ctx.builder.build_int_truncate_or_bit_cast(src_len, llvm_i32, "srclen32").unwrap();
 
     // index in bound and positive should be done
     // assert if dest.step == 1 then len(src) <= len(dest) else len(src) == len(dest), and
@@ -136,7 +146,7 @@ pub fn list_slice_assignment<'ctx, G: CodeGenerator + ?Sized>(
                     BasicTypeEnum::StructType(t) => t.size_of().unwrap(),
                     _ => codegen_unreachable!(ctx),
                 };
-                ctx.builder.build_int_truncate_or_bit_cast(s, int32, "size").unwrap()
+                ctx.builder.build_int_truncate_or_bit_cast(s, llvm_i32, "size").unwrap()
             }
             .into(),
         ];
@@ -147,6 +157,7 @@ pub fn list_slice_assignment<'ctx, G: CodeGenerator + ?Sized>(
             .map(Either::unwrap_left)
             .unwrap()
     };
+
     // update length
     let need_update =
         ctx.builder.build_int_compare(IntPredicate::NE, new_len, dest_len, "need_update").unwrap();
@@ -155,7 +166,8 @@ 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();
+    let new_len =
+        ctx.builder.build_int_z_extend_or_bit_cast(new_len, llvm_usize, "new_len").unwrap();
     dest_arr.store_size(ctx, generator, new_len);
     ctx.builder.build_unconditional_branch(cont_bb).unwrap();
     ctx.builder.position_at_end(cont_bb);
diff --git a/nac3core/src/codegen/irrt/math.rs b/nac3core/src/codegen/irrt/math.rs
index 4bc95913..33445b2a 100644
--- a/nac3core/src/codegen/irrt/math.rs
+++ b/nac3core/src/codegen/irrt/math.rs
@@ -62,8 +62,13 @@ pub fn call_isinf<'ctx, G: CodeGenerator + ?Sized>(
     ctx: &CodeGenContext<'ctx, '_>,
     v: FloatValue<'ctx>,
 ) -> IntValue<'ctx> {
+    let llvm_i32 = ctx.ctx.i32_type();
+    let llvm_f64 = ctx.ctx.f64_type();
+
+    assert_eq!(v.get_type(), llvm_f64);
+
     let intrinsic_fn = ctx.module.get_function("__nac3_isinf").unwrap_or_else(|| {
-        let fn_type = ctx.ctx.i32_type().fn_type(&[ctx.ctx.f64_type().into()], false);
+        let fn_type = llvm_i32.fn_type(&[llvm_f64.into()], false);
         ctx.module.add_function("__nac3_isinf", fn_type, None)
     });
 
@@ -84,8 +89,13 @@ pub fn call_isnan<'ctx, G: CodeGenerator + ?Sized>(
     ctx: &CodeGenContext<'ctx, '_>,
     v: FloatValue<'ctx>,
 ) -> IntValue<'ctx> {
+    let llvm_i32 = ctx.ctx.i32_type();
+    let llvm_f64 = ctx.ctx.f64_type();
+
+    assert_eq!(v.get_type(), llvm_f64);
+
     let intrinsic_fn = ctx.module.get_function("__nac3_isnan").unwrap_or_else(|| {
-        let fn_type = ctx.ctx.i32_type().fn_type(&[ctx.ctx.f64_type().into()], false);
+        let fn_type = llvm_i32.fn_type(&[llvm_f64.into()], false);
         ctx.module.add_function("__nac3_isnan", fn_type, None)
     });
 
@@ -104,6 +114,8 @@ pub fn call_isnan<'ctx, G: CodeGenerator + ?Sized>(
 pub fn call_gamma<'ctx>(ctx: &CodeGenContext<'ctx, '_>, v: FloatValue<'ctx>) -> FloatValue<'ctx> {
     let llvm_f64 = ctx.ctx.f64_type();
 
+    assert_eq!(v.get_type(), llvm_f64);
+
     let intrinsic_fn = ctx.module.get_function("__nac3_gamma").unwrap_or_else(|| {
         let fn_type = llvm_f64.fn_type(&[llvm_f64.into()], false);
         ctx.module.add_function("__nac3_gamma", fn_type, None)
@@ -121,6 +133,8 @@ pub fn call_gamma<'ctx>(ctx: &CodeGenContext<'ctx, '_>, v: FloatValue<'ctx>) ->
 pub fn call_gammaln<'ctx>(ctx: &CodeGenContext<'ctx, '_>, v: FloatValue<'ctx>) -> FloatValue<'ctx> {
     let llvm_f64 = ctx.ctx.f64_type();
 
+    assert_eq!(v.get_type(), llvm_f64);
+
     let intrinsic_fn = ctx.module.get_function("__nac3_gammaln").unwrap_or_else(|| {
         let fn_type = llvm_f64.fn_type(&[llvm_f64.into()], false);
         ctx.module.add_function("__nac3_gammaln", fn_type, None)
@@ -138,6 +152,8 @@ pub fn call_gammaln<'ctx>(ctx: &CodeGenContext<'ctx, '_>, v: FloatValue<'ctx>) -
 pub fn call_j0<'ctx>(ctx: &CodeGenContext<'ctx, '_>, v: FloatValue<'ctx>) -> FloatValue<'ctx> {
     let llvm_f64 = ctx.ctx.f64_type();
 
+    assert_eq!(v.get_type(), llvm_f64);
+
     let intrinsic_fn = ctx.module.get_function("__nac3_j0").unwrap_or_else(|| {
         let fn_type = llvm_f64.fn_type(&[llvm_f64.into()], false);
         ctx.module.add_function("__nac3_j0", fn_type, None)
diff --git a/nac3core/src/codegen/irrt/mod.rs b/nac3core/src/codegen/irrt/mod.rs
index 824921cd..c8dfba2b 100644
--- a/nac3core/src/codegen/irrt/mod.rs
+++ b/nac3core/src/codegen/irrt/mod.rs
@@ -130,10 +130,11 @@ pub fn handle_slice_indices<'ctx, G: CodeGenerator>(
     generator: &mut G,
     length: IntValue<'ctx>,
 ) -> Result<Option<(IntValue<'ctx>, IntValue<'ctx>, IntValue<'ctx>)>, String> {
-    let int32 = ctx.ctx.i32_type();
-    let zero = int32.const_zero();
-    let one = int32.const_int(1, false);
-    let length = ctx.builder.build_int_truncate_or_bit_cast(length, int32, "leni32").unwrap();
+    let llvm_i32 = ctx.ctx.i32_type();
+
+    let zero = llvm_i32.const_zero();
+    let one = llvm_i32.const_int(1, false);
+    let length = ctx.builder.build_int_truncate_or_bit_cast(length, llvm_i32, "leni32").unwrap();
     Ok(Some(match (start, end, step) {
         (s, e, None) => (
             if let Some(s) = s.as_ref() {
@@ -142,7 +143,7 @@ pub fn handle_slice_indices<'ctx, G: CodeGenerator>(
                     None => return Ok(None),
                 }
             } else {
-                int32.const_zero()
+                llvm_i32.const_zero()
             },
             {
                 let e = if let Some(s) = e.as_ref() {
diff --git a/nac3core/src/codegen/irrt/ndarray/basic.rs b/nac3core/src/codegen/irrt/ndarray/basic.rs
index 0daea1c4..d11c9b8d 100644
--- a/nac3core/src/codegen/irrt/ndarray/basic.rs
+++ b/nac3core/src/codegen/irrt/ndarray/basic.rs
@@ -1,4 +1,5 @@
 use inkwell::{
+    types::BasicTypeEnum,
     values::{BasicValueEnum, IntValue, PointerValue},
     AddressSpace,
 };
@@ -7,19 +8,26 @@ use crate::codegen::{
     expr::{create_and_call_function, infer_and_call_function},
     irrt::get_usize_dependent_function_name,
     types::ProxyType,
-    values::{ndarray::NDArrayValue, ProxyValue},
+    values::{ndarray::NDArrayValue, ProxyValue, TypedArrayLikeAccessor},
     CodeGenContext, CodeGenerator,
 };
 
+/// Generates a call to `__nac3_ndarray_util_assert_shape_no_negative`.
+///
+/// Assets that `shape` does not contain negative dimensions.
 pub fn call_nac3_ndarray_util_assert_shape_no_negative<'ctx, G: CodeGenerator + ?Sized>(
     generator: &G,
     ctx: &CodeGenContext<'ctx, '_>,
-    ndims: IntValue<'ctx>,
-    shape: PointerValue<'ctx>,
+    shape: &impl TypedArrayLikeAccessor<'ctx, G, IntValue<'ctx>>,
 ) {
     let llvm_usize = generator.get_size_type(ctx.ctx);
     let llvm_pusize = llvm_usize.ptr_type(AddressSpace::default());
 
+    assert_eq!(
+        BasicTypeEnum::try_from(shape.element_type(ctx, generator)).unwrap(),
+        llvm_usize.into()
+    );
+
     let name = get_usize_dependent_function_name(
         generator,
         ctx,
@@ -30,23 +38,37 @@ pub fn call_nac3_ndarray_util_assert_shape_no_negative<'ctx, G: CodeGenerator +
         ctx,
         &name,
         Some(llvm_usize.into()),
-        &[(llvm_usize.into(), ndims.into()), (llvm_pusize.into(), shape.into())],
+        &[
+            (llvm_usize.into(), shape.size(ctx, generator).into()),
+            (llvm_pusize.into(), shape.base_ptr(ctx, generator).into()),
+        ],
         None,
         None,
     );
 }
 
+/// Generates a call to `__nac3_ndarray_util_assert_shape_output_shape_same`.
+///
+/// Asserts that `ndarray_shape` and `output_shape` are the same in the context of writing output to
+/// an `ndarray`.
 pub fn call_nac3_ndarray_util_assert_output_shape_same<'ctx, G: CodeGenerator + ?Sized>(
     generator: &G,
     ctx: &CodeGenContext<'ctx, '_>,
-    ndarray_ndims: IntValue<'ctx>,
-    ndarray_shape: PointerValue<'ctx>,
-    output_ndims: IntValue<'ctx>,
-    output_shape: IntValue<'ctx>,
+    ndarray_shape: &impl TypedArrayLikeAccessor<'ctx, G, IntValue<'ctx>>,
+    output_shape: &impl TypedArrayLikeAccessor<'ctx, G, IntValue<'ctx>>,
 ) {
     let llvm_usize = generator.get_size_type(ctx.ctx);
     let llvm_pusize = llvm_usize.ptr_type(AddressSpace::default());
 
+    assert_eq!(
+        BasicTypeEnum::try_from(ndarray_shape.element_type(ctx, generator)).unwrap(),
+        llvm_usize.into()
+    );
+    assert_eq!(
+        BasicTypeEnum::try_from(output_shape.element_type(ctx, generator)).unwrap(),
+        llvm_usize.into()
+    );
+
     let name = get_usize_dependent_function_name(
         generator,
         ctx,
@@ -58,16 +80,20 @@ pub fn call_nac3_ndarray_util_assert_output_shape_same<'ctx, G: CodeGenerator +
         &name,
         Some(llvm_usize.into()),
         &[
-            (llvm_usize.into(), ndarray_ndims.into()),
-            (llvm_pusize.into(), ndarray_shape.into()),
-            (llvm_usize.into(), output_ndims.into()),
-            (llvm_pusize.into(), output_shape.into()),
+            (llvm_usize.into(), ndarray_shape.size(ctx, generator).into()),
+            (llvm_pusize.into(), ndarray_shape.base_ptr(ctx, generator).into()),
+            (llvm_usize.into(), output_shape.size(ctx, generator).into()),
+            (llvm_pusize.into(), output_shape.base_ptr(ctx, generator).into()),
         ],
         None,
         None,
     );
 }
 
+/// Generates a call to `__nac3_ndarray_size`.
+///
+/// Returns a [`usize`][CodeGenerator::get_size_type] value of the number of elements of an
+/// `ndarray`, corresponding to the value of `ndarray.size`.
 pub fn call_nac3_ndarray_size<'ctx, G: CodeGenerator + ?Sized>(
     generator: &G,
     ctx: &CodeGenContext<'ctx, '_>,
@@ -90,6 +116,10 @@ pub fn call_nac3_ndarray_size<'ctx, G: CodeGenerator + ?Sized>(
     .unwrap()
 }
 
+/// Generates a call to `__nac3_ndarray_nbytes`.
+///
+/// Returns a [`usize`][CodeGenerator::get_size_type] value of the number of bytes consumed by the
+/// data of the `ndarray`, corresponding to the value of `ndarray.nbytes`.
 pub fn call_nac3_ndarray_nbytes<'ctx, G: CodeGenerator + ?Sized>(
     generator: &G,
     ctx: &CodeGenContext<'ctx, '_>,
@@ -112,6 +142,10 @@ pub fn call_nac3_ndarray_nbytes<'ctx, G: CodeGenerator + ?Sized>(
     .unwrap()
 }
 
+/// Generates a call to `__nac3_ndarray_len`.
+///
+/// Returns a [`usize`][CodeGenerator::get_size_type] value of the size of the topmost dimension of
+/// the `ndarray`, corresponding to the value of `ndarray.__len__`.
 pub fn call_nac3_ndarray_len<'ctx, G: CodeGenerator + ?Sized>(
     generator: &G,
     ctx: &CodeGenContext<'ctx, '_>,
@@ -134,6 +168,9 @@ pub fn call_nac3_ndarray_len<'ctx, G: CodeGenerator + ?Sized>(
     .unwrap()
 }
 
+/// Generates a call to `__nac3_ndarray_is_c_contiguous`.
+///
+/// Returns an `i1` value indicating whether the `ndarray` is C-contiguous.
 pub fn call_nac3_ndarray_is_c_contiguous<'ctx, G: CodeGenerator + ?Sized>(
     generator: &G,
     ctx: &CodeGenContext<'ctx, '_>,
@@ -156,6 +193,9 @@ pub fn call_nac3_ndarray_is_c_contiguous<'ctx, G: CodeGenerator + ?Sized>(
     .unwrap()
 }
 
+/// Generates a call to `__nac3_ndarray_get_nth_pelement`.
+///
+/// Returns a [`PointerValue`] to the `index`-th flattened element of the `ndarray`.
 pub fn call_nac3_ndarray_get_nth_pelement<'ctx, G: CodeGenerator + ?Sized>(
     generator: &G,
     ctx: &CodeGenContext<'ctx, '_>,
@@ -167,6 +207,8 @@ pub fn call_nac3_ndarray_get_nth_pelement<'ctx, G: CodeGenerator + ?Sized>(
     let llvm_usize = generator.get_size_type(ctx.ctx);
     let llvm_ndarray = ndarray.get_type().as_base_type();
 
+    assert_eq!(index.get_type(), llvm_usize);
+
     let name = get_usize_dependent_function_name(generator, ctx, "__nac3_ndarray_get_nth_pelement");
 
     create_and_call_function(
@@ -181,11 +223,16 @@ pub fn call_nac3_ndarray_get_nth_pelement<'ctx, G: CodeGenerator + ?Sized>(
     .unwrap()
 }
 
+/// Generates a call to `__nac3_ndarray_get_pelement_by_indices`.
+///
+/// `indices` must have the same number of elements as the number of dimensions in `ndarray`.
+///
+/// Returns a [`PointerValue`] to the element indexed by `indices`.
 pub fn call_nac3_ndarray_get_pelement_by_indices<'ctx, G: CodeGenerator + ?Sized>(
     generator: &G,
     ctx: &CodeGenContext<'ctx, '_>,
     ndarray: NDArrayValue<'ctx>,
-    indices: PointerValue<'ctx>,
+    indices: &impl TypedArrayLikeAccessor<'ctx, G, IntValue<'ctx>>,
 ) -> PointerValue<'ctx> {
     let llvm_i8 = ctx.ctx.i8_type();
     let llvm_pi8 = llvm_i8.ptr_type(AddressSpace::default());
@@ -193,6 +240,11 @@ pub fn call_nac3_ndarray_get_pelement_by_indices<'ctx, G: CodeGenerator + ?Sized
     let llvm_pusize = llvm_usize.ptr_type(AddressSpace::default());
     let llvm_ndarray = ndarray.get_type().as_base_type();
 
+    assert_eq!(
+        BasicTypeEnum::try_from(indices.element_type(ctx, generator)).unwrap(),
+        llvm_usize.into()
+    );
+
     let name =
         get_usize_dependent_function_name(generator, ctx, "__nac3_ndarray_get_pelement_by_indices");
 
@@ -202,7 +254,7 @@ pub fn call_nac3_ndarray_get_pelement_by_indices<'ctx, G: CodeGenerator + ?Sized
         Some(llvm_pi8.into()),
         &[
             (llvm_ndarray.into(), ndarray.as_base_value().into()),
-            (llvm_pusize.into(), indices.into()),
+            (llvm_pusize.into(), indices.base_ptr(ctx, generator).into()),
         ],
         Some("pelement"),
         None,
@@ -211,6 +263,9 @@ pub fn call_nac3_ndarray_get_pelement_by_indices<'ctx, G: CodeGenerator + ?Sized
     .unwrap()
 }
 
+/// Generates a call to `__nac3_ndarray_set_strides_by_shape`.
+///
+/// Sets `ndarray.strides` assuming that `ndarray.shape` is C-contiguous.
 pub fn call_nac3_ndarray_set_strides_by_shape<'ctx, G: CodeGenerator + ?Sized>(
     generator: &G,
     ctx: &CodeGenContext<'ctx, '_>,
@@ -231,6 +286,11 @@ pub fn call_nac3_ndarray_set_strides_by_shape<'ctx, G: CodeGenerator + ?Sized>(
     );
 }
 
+/// Generates a call to `__nac3_ndarray_copy_data`.
+///
+/// Copies all elements from `src_ndarray` to `dst_ndarray` using their flattened views. The number
+/// of elements in `src_ndarray` must be greater than or equal to the number of elements in
+/// `dst_ndarray`.
 pub fn call_nac3_ndarray_copy_data<'ctx, G: CodeGenerator + ?Sized>(
     generator: &G,
     ctx: &CodeGenContext<'ctx, '_>,
diff --git a/nac3core/src/codegen/irrt/ndarray/indexing.rs b/nac3core/src/codegen/irrt/ndarray/indexing.rs
index 0821b2cd..3e2c908d 100644
--- a/nac3core/src/codegen/irrt/ndarray/indexing.rs
+++ b/nac3core/src/codegen/irrt/ndarray/indexing.rs
@@ -5,6 +5,11 @@ use crate::codegen::{
     CodeGenContext, CodeGenerator,
 };
 
+/// Generates a call to `__nac3_ndarray_index`.
+///
+/// Performs [basic indexing](https://numpy.org/doc/stable/user/basics.indexing.html#basic-indexing)
+/// on `src_ndarray` using `indices`, writing the result to `dst_ndarray`, corresponding to the
+/// operation `dst_ndarray = src_ndarray[indices]`.
 pub fn call_nac3_ndarray_index<'ctx, G: CodeGenerator + ?Sized>(
     generator: &G,
     ctx: &CodeGenContext<'ctx, '_>,
diff --git a/nac3core/src/codegen/irrt/ndarray/iter.rs b/nac3core/src/codegen/irrt/ndarray/iter.rs
index 966d6605..47cd5b29 100644
--- a/nac3core/src/codegen/irrt/ndarray/iter.rs
+++ b/nac3core/src/codegen/irrt/ndarray/iter.rs
@@ -1,4 +1,5 @@
 use inkwell::{
+    types::BasicTypeEnum,
     values::{BasicValueEnum, IntValue},
     AddressSpace,
 };
@@ -9,21 +10,29 @@ use crate::codegen::{
     types::ProxyType,
     values::{
         ndarray::{NDArrayValue, NDIterValue},
-        ArrayLikeValue, ArraySliceValue, ProxyValue,
+        ProxyValue, TypedArrayLikeAccessor,
     },
     CodeGenContext, CodeGenerator,
 };
 
+/// Generates a call to `__nac3_nditer_initialize`.
+///
+/// Initializes the `iter` object.
 pub fn call_nac3_nditer_initialize<'ctx, G: CodeGenerator + ?Sized>(
     generator: &G,
     ctx: &CodeGenContext<'ctx, '_>,
     iter: NDIterValue<'ctx>,
     ndarray: NDArrayValue<'ctx>,
-    indices: ArraySliceValue<'ctx>,
+    indices: &impl TypedArrayLikeAccessor<'ctx, G, IntValue<'ctx>>,
 ) {
     let llvm_usize = generator.get_size_type(ctx.ctx);
     let llvm_pusize = llvm_usize.ptr_type(AddressSpace::default());
 
+    assert_eq!(
+        BasicTypeEnum::try_from(indices.element_type(ctx, generator)).unwrap(),
+        llvm_usize.into()
+    );
+
     let name = get_usize_dependent_function_name(generator, ctx, "__nac3_nditer_initialize");
 
     create_and_call_function(
@@ -40,6 +49,10 @@ pub fn call_nac3_nditer_initialize<'ctx, G: CodeGenerator + ?Sized>(
     );
 }
 
+/// Generates a call to `__nac3_nditer_initialize_has_element`.
+///
+/// Returns an `i1` value indicating whether there are elements left to traverse for the `iter`
+/// object.
 pub fn call_nac3_nditer_has_element<'ctx, G: CodeGenerator + ?Sized>(
     generator: &G,
     ctx: &CodeGenContext<'ctx, '_>,
@@ -59,6 +72,9 @@ pub fn call_nac3_nditer_has_element<'ctx, G: CodeGenerator + ?Sized>(
     .unwrap()
 }
 
+/// Generates a call to `__nac3_nditer_next`.
+///
+/// Moves `iter` to point to the next element.
 pub fn call_nac3_nditer_next<'ctx, G: CodeGenerator + ?Sized>(
     generator: &G,
     ctx: &CodeGenContext<'ctx, '_>,
diff --git a/nac3core/src/codegen/irrt/ndarray/mod.rs b/nac3core/src/codegen/irrt/ndarray/mod.rs
index 56d9094d..b74ace0f 100644
--- a/nac3core/src/codegen/irrt/ndarray/mod.rs
+++ b/nac3core/src/codegen/irrt/ndarray/mod.rs
@@ -1,10 +1,11 @@
 use inkwell::{
-    types::IntType,
+    types::{BasicTypeEnum, IntType},
     values::{BasicValueEnum, CallSiteValue, IntValue},
     AddressSpace, IntPredicate,
 };
 use itertools::Either;
 
+use super::get_usize_dependent_function_name;
 use crate::codegen::{
     llvm_intrinsics,
     macros::codegen_unreachable,
@@ -23,8 +24,8 @@ mod basic;
 mod indexing;
 mod iter;
 
-/// Generates a call to `__nac3_ndarray_calc_size`. Returns an [`IntValue`] representing the
-/// calculated total size.
+/// Generates a call to `__nac3_ndarray_calc_size`. Returns a
+/// [`usize`][CodeGenerator::get_size_type] representing the calculated total size.
 ///
 /// * `dims` - An [`ArrayLikeIndexer`] containing the size of each dimension.
 /// * `range` - The dimension index to begin and end (exclusively) calculating the dimensions for,
@@ -43,18 +44,22 @@ where
     let llvm_usize = generator.get_size_type(ctx.ctx);
     let llvm_pusize = llvm_usize.ptr_type(AddressSpace::default());
 
-    let ndarray_calc_size_fn_name = match llvm_usize.get_bit_width() {
-        32 => "__nac3_ndarray_calc_size",
-        64 => "__nac3_ndarray_calc_size64",
-        bw => codegen_unreachable!(ctx, "Unsupported size type bit width: {}", bw),
-    };
+    assert!(begin.is_none_or(|begin| begin.get_type() == llvm_usize));
+    assert!(end.is_none_or(|end| end.get_type() == llvm_usize));
+    assert_eq!(
+        BasicTypeEnum::try_from(dims.element_type(ctx, generator)).unwrap(),
+        llvm_usize.into()
+    );
+
+    let ndarray_calc_size_fn_name =
+        get_usize_dependent_function_name(generator, ctx, "__nac3_ndarray_calc_size");
     let ndarray_calc_size_fn_t = llvm_usize.fn_type(
         &[llvm_pusize.into(), llvm_usize.into(), llvm_usize.into(), llvm_usize.into()],
         false,
     );
     let ndarray_calc_size_fn =
-        ctx.module.get_function(ndarray_calc_size_fn_name).unwrap_or_else(|| {
-            ctx.module.add_function(ndarray_calc_size_fn_name, ndarray_calc_size_fn_t, None)
+        ctx.module.get_function(&ndarray_calc_size_fn_name).unwrap_or_else(|| {
+            ctx.module.add_function(&ndarray_calc_size_fn_name, ndarray_calc_size_fn_t, None)
         });
 
     let begin = begin.unwrap_or_else(|| llvm_usize.const_zero());
@@ -76,10 +81,10 @@ where
         .unwrap()
 }
 
-/// Generates a call to `__nac3_ndarray_calc_nd_indices`. Returns a [`TypeArrayLikeAdpater`]
+/// Generates a call to `__nac3_ndarray_calc_nd_indices`. Returns a [`TypedArrayLikeAdapter`]
 /// containing `i32` indices of the flattened index.
 ///
-/// * `index` - The index to compute the multidimensional index for.
+/// * `index` - The `llvm_usize` index to compute the multidimensional index for.
 /// * `ndarray` - LLVM pointer to the `NDArray`. This value must be the LLVM representation of an
 ///   `NDArray`.
 pub fn call_ndarray_calc_nd_indices<'ctx, G: CodeGenerator + ?Sized>(
@@ -94,19 +99,18 @@ pub fn call_ndarray_calc_nd_indices<'ctx, G: CodeGenerator + ?Sized>(
     let llvm_pi32 = llvm_i32.ptr_type(AddressSpace::default());
     let llvm_pusize = llvm_usize.ptr_type(AddressSpace::default());
 
-    let ndarray_calc_nd_indices_fn_name = match llvm_usize.get_bit_width() {
-        32 => "__nac3_ndarray_calc_nd_indices",
-        64 => "__nac3_ndarray_calc_nd_indices64",
-        bw => codegen_unreachable!(ctx, "Unsupported size type bit width: {}", bw),
-    };
+    assert_eq!(index.get_type(), llvm_usize);
+
+    let ndarray_calc_nd_indices_fn_name =
+        get_usize_dependent_function_name(generator, ctx, "__nac3_ndarray_calc_nd_indices");
     let ndarray_calc_nd_indices_fn =
-        ctx.module.get_function(ndarray_calc_nd_indices_fn_name).unwrap_or_else(|| {
+        ctx.module.get_function(&ndarray_calc_nd_indices_fn_name).unwrap_or_else(|| {
             let fn_type = llvm_void.fn_type(
                 &[llvm_usize.into(), llvm_pusize.into(), llvm_usize.into(), llvm_pi32.into()],
                 false,
             );
 
-            ctx.module.add_function(ndarray_calc_nd_indices_fn_name, fn_type, None)
+            ctx.module.add_function(&ndarray_calc_nd_indices_fn_name, fn_type, None)
         });
 
     let ndarray_num_dims = ndarray.load_ndims(ctx);
@@ -134,15 +138,21 @@ pub fn call_ndarray_calc_nd_indices<'ctx, G: CodeGenerator + ?Sized>(
     )
 }
 
-fn call_ndarray_flatten_index_impl<'ctx, G, Indices>(
+/// Generates a call to `__nac3_ndarray_flatten_index`. Returns a `usize` of the flattened index for
+/// the multidimensional index.
+///
+/// * `ndarray` - LLVM pointer to the `NDArray`. This value must be the LLVM representation of an
+///   `NDArray`.
+/// * `indices` - The multidimensional index to compute the flattened index for.
+pub fn call_ndarray_flatten_index<'ctx, G, Index>(
     generator: &G,
     ctx: &CodeGenContext<'ctx, '_>,
     ndarray: NDArrayValue<'ctx>,
-    indices: &Indices,
+    indices: &Index,
 ) -> IntValue<'ctx>
 where
     G: CodeGenerator + ?Sized,
-    Indices: ArrayLikeIndexer<'ctx>,
+    Index: ArrayLikeIndexer<'ctx>,
 {
     let llvm_i32 = ctx.ctx.i32_type();
     let llvm_usize = generator.get_size_type(ctx.ctx);
@@ -163,19 +173,16 @@ where
         "Expected usize integer value for argument `indices_size` to `call_ndarray_flatten_index_impl`"
     );
 
-    let ndarray_flatten_index_fn_name = match llvm_usize.get_bit_width() {
-        32 => "__nac3_ndarray_flatten_index",
-        64 => "__nac3_ndarray_flatten_index64",
-        bw => codegen_unreachable!(ctx, "Unsupported size type bit width: {}", bw),
-    };
+    let ndarray_flatten_index_fn_name =
+        get_usize_dependent_function_name(generator, ctx, "__nac3_ndarray_flatten_index");
     let ndarray_flatten_index_fn =
-        ctx.module.get_function(ndarray_flatten_index_fn_name).unwrap_or_else(|| {
+        ctx.module.get_function(&ndarray_flatten_index_fn_name).unwrap_or_else(|| {
             let fn_type = llvm_usize.fn_type(
                 &[llvm_pusize.into(), llvm_usize.into(), llvm_pi32.into(), llvm_usize.into()],
                 false,
             );
 
-            ctx.module.add_function(ndarray_flatten_index_fn_name, fn_type, None)
+            ctx.module.add_function(&ndarray_flatten_index_fn_name, fn_type, None)
         });
 
     let ndarray_num_dims = ndarray.load_ndims(ctx);
@@ -201,27 +208,8 @@ where
     index
 }
 
-/// Generates a call to `__nac3_ndarray_flatten_index`. Returns the flattened index for the
-/// multidimensional index.
-///
-/// * `ndarray` - LLVM pointer to the `NDArray`. This value must be the LLVM representation of an
-///   `NDArray`.
-/// * `indices` - The multidimensional index to compute the flattened index for.
-pub fn call_ndarray_flatten_index<'ctx, G, Index>(
-    generator: &G,
-    ctx: &CodeGenContext<'ctx, '_>,
-    ndarray: NDArrayValue<'ctx>,
-    indices: &Index,
-) -> IntValue<'ctx>
-where
-    G: CodeGenerator + ?Sized,
-    Index: ArrayLikeIndexer<'ctx>,
-{
-    call_ndarray_flatten_index_impl(generator, ctx, ndarray, indices)
-}
-
-/// Generates a call to `__nac3_ndarray_calc_broadcast`. Returns a tuple containing the number of
-/// dimension and size of each dimension of the resultant `ndarray`.
+/// Generates a call to `__nac3_ndarray_calc_broadcast`. Returns a [`TypedArrayLikeAdapter`]
+/// containing the size of each dimension of the resultant `ndarray`.
 pub fn call_ndarray_calc_broadcast<'ctx, G: CodeGenerator + ?Sized>(
     generator: &mut G,
     ctx: &mut CodeGenContext<'ctx, '_>,
@@ -231,13 +219,10 @@ pub fn call_ndarray_calc_broadcast<'ctx, G: CodeGenerator + ?Sized>(
     let llvm_usize = generator.get_size_type(ctx.ctx);
     let llvm_pusize = llvm_usize.ptr_type(AddressSpace::default());
 
-    let ndarray_calc_broadcast_fn_name = match llvm_usize.get_bit_width() {
-        32 => "__nac3_ndarray_calc_broadcast",
-        64 => "__nac3_ndarray_calc_broadcast64",
-        bw => codegen_unreachable!(ctx, "Unsupported size type bit width: {}", bw),
-    };
+    let ndarray_calc_broadcast_fn_name =
+        get_usize_dependent_function_name(generator, ctx, "__nac3_ndarray_calc_broadcast");
     let ndarray_calc_broadcast_fn =
-        ctx.module.get_function(ndarray_calc_broadcast_fn_name).unwrap_or_else(|| {
+        ctx.module.get_function(&ndarray_calc_broadcast_fn_name).unwrap_or_else(|| {
             let fn_type = llvm_usize.fn_type(
                 &[
                     llvm_pusize.into(),
@@ -249,7 +234,7 @@ pub fn call_ndarray_calc_broadcast<'ctx, G: CodeGenerator + ?Sized>(
                 false,
             );
 
-            ctx.module.add_function(ndarray_calc_broadcast_fn_name, fn_type, None)
+            ctx.module.add_function(&ndarray_calc_broadcast_fn_name, fn_type, None)
         });
 
     let lhs_ndims = lhs.load_ndims(ctx);
diff --git a/nac3core/src/codegen/irrt/range.rs b/nac3core/src/codegen/irrt/range.rs
index 47c63c4f..3b6bc31d 100644
--- a/nac3core/src/codegen/irrt/range.rs
+++ b/nac3core/src/codegen/irrt/range.rs
@@ -6,6 +6,13 @@ use itertools::Either;
 
 use crate::codegen::{CodeGenContext, CodeGenerator};
 
+/// Invokes the `__nac3_range_slice_len` in IRRT.
+///
+/// - `start`: The `i32` start value for the slice.
+/// - `end`: The `i32` end value for the slice.
+/// - `step`: The `i32` step value for the slice.
+///
+/// Returns an `i32` value of the length of the slice.
 pub fn calculate_len_for_slice_range<'ctx, G: CodeGenerator + ?Sized>(
     generator: &mut G,
     ctx: &mut CodeGenContext<'ctx, '_>,
@@ -14,9 +21,15 @@ pub fn calculate_len_for_slice_range<'ctx, G: CodeGenerator + ?Sized>(
     step: IntValue<'ctx>,
 ) -> IntValue<'ctx> {
     const SYMBOL: &str = "__nac3_range_slice_len";
+
+    let llvm_i32 = ctx.ctx.i32_type();
+
+    assert_eq!(start.get_type(), llvm_i32);
+    assert_eq!(end.get_type(), llvm_i32);
+    assert_eq!(step.get_type(), llvm_i32);
+
     let len_func = ctx.module.get_function(SYMBOL).unwrap_or_else(|| {
-        let i32_t = ctx.ctx.i32_type();
-        let fn_t = i32_t.fn_type(&[i32_t.into(), i32_t.into(), i32_t.into()], false);
+        let fn_t = llvm_i32.fn_type(&[llvm_i32.into(), llvm_i32.into(), llvm_i32.into()], false);
         ctx.module.add_function(SYMBOL, fn_t, None)
     });
 
@@ -33,6 +46,7 @@ pub fn calculate_len_for_slice_range<'ctx, G: CodeGenerator + ?Sized>(
         [None, None, None],
         ctx.current_loc,
     );
+
     ctx.builder
         .build_call(len_func, &[start.into(), end.into(), step.into()], "calc_len")
         .map(CallSiteValue::try_as_basic_value)
diff --git a/nac3core/src/codegen/types/ndarray/nditer.rs b/nac3core/src/codegen/types/ndarray/nditer.rs
index c9b6b7d5..772d5b23 100644
--- a/nac3core/src/codegen/types/ndarray/nditer.rs
+++ b/nac3core/src/codegen/types/ndarray/nditer.rs
@@ -14,7 +14,7 @@ use crate::codegen::{
     types::structure::{check_struct_type_matches_fields, StructField, StructFields},
     values::{
         ndarray::{NDArrayValue, NDIterValue},
-        ArraySliceValue, ProxyValue,
+        ArrayLikeValue, ArraySliceValue, ProxyValue, TypedArrayLikeAdapter,
     },
     CodeGenContext, CodeGenerator,
 };
@@ -128,6 +128,11 @@ impl<'ctx> NDIterType<'ctx> {
     }
 
     /// Allocate an [`NDIter`] that iterates through the given `ndarray`.
+    ///
+    /// Note: This function allocates an array on the stack at the current builder location, which
+    /// may lead to stack explosion if called in a hot loop. Therefore, callers are recommended to
+    /// call `llvm.stacksave` before calling this function and call `llvm.stackrestore` after the
+    /// [`NDIter`] is no longer needed.
     #[must_use]
     pub fn construct<G: CodeGenerator + ?Sized>(
         &self,
@@ -141,16 +146,12 @@ impl<'ctx> NDIterType<'ctx> {
         // The caller has the responsibility to allocate 'indices' for `NDIter`.
         let indices =
             generator.gen_array_var_alloc(ctx, self.llvm_usize.into(), ndims, None).unwrap();
+        let indices =
+            TypedArrayLikeAdapter::from(indices, |_, _, v| v.into_int_value(), |_, _, v| v.into());
 
-        let nditer = <Self as ProxyType<'ctx>>::Value::from_pointer_value(
-            nditer,
-            ndarray,
-            indices,
-            self.llvm_usize,
-            None,
-        );
+        let nditer = self.map_value(nditer, ndarray, indices.as_slice_value(ctx, generator), None);
 
-        irrt::ndarray::call_nac3_nditer_initialize(generator, ctx, nditer, ndarray, indices);
+        irrt::ndarray::call_nac3_nditer_initialize(generator, ctx, nditer, ndarray, &indices);
 
         nditer
     }
diff --git a/nac3core/src/codegen/values/array.rs b/nac3core/src/codegen/values/array.rs
index 9f3ec0e4..55e91b21 100644
--- a/nac3core/src/codegen/values/array.rs
+++ b/nac3core/src/codegen/values/array.rs
@@ -265,6 +265,14 @@ where
     ) -> IntValue<'ctx> {
         self.adapted.size(ctx, generator)
     }
+
+    fn as_slice_value<CG: CodeGenerator + ?Sized>(
+        &self,
+        ctx: &CodeGenContext<'ctx, '_>,
+        generator: &CG,
+    ) -> ArraySliceValue<'ctx> {
+        self.adapted.as_slice_value(ctx, generator)
+    }
 }
 
 impl<'ctx, G: CodeGenerator + ?Sized, T, Index, Adapted> ArrayLikeIndexer<'ctx, Index>
diff --git a/nac3core/src/codegen/values/ndarray/mod.rs b/nac3core/src/codegen/values/ndarray/mod.rs
index 0da3a2ee..4c5be432 100644
--- a/nac3core/src/codegen/values/ndarray/mod.rs
+++ b/nac3core/src/codegen/values/ndarray/mod.rs
@@ -358,6 +358,10 @@ impl<'ctx> NDArrayValue<'ctx> {
         irrt::ndarray::call_nac3_ndarray_set_strides_by_shape(generator, ctx, *self);
     }
 
+    /// Clone/Copy this ndarray - Allocate a new ndarray with the same shape as this ndarray and
+    /// copy the contents over.
+    ///
+    /// The new ndarray will own its data and will be C-contiguous.
     #[must_use]
     pub fn make_copy<G: CodeGenerator + ?Sized>(
         &self,
diff --git a/nac3core/src/codegen/values/ndarray/nditer.rs b/nac3core/src/codegen/values/ndarray/nditer.rs
index 22f1bcad..4b4e07a1 100644
--- a/nac3core/src/codegen/values/ndarray/nditer.rs
+++ b/nac3core/src/codegen/values/ndarray/nditer.rs
@@ -69,7 +69,10 @@ impl<'ctx> NDIterValue<'ctx> {
         irrt::ndarray::call_nac3_nditer_next(generator, ctx, *self);
     }
 
-    fn element_field(&self, ctx: &CodeGenContext<'ctx, '_>) -> StructField<'ctx, PointerValue<'ctx>> {
+    fn element_field(
+        &self,
+        ctx: &CodeGenContext<'ctx, '_>,
+    ) -> StructField<'ctx, PointerValue<'ctx>> {
         self.get_type().get_fields(ctx.ctx).element
     }
 
@@ -138,6 +141,10 @@ impl<'ctx> NDArrayValue<'ctx> {
     ///
     /// `body` has access to [`BreakContinueHooks`] to short-circuit and [`NDIterValue`] to
     /// get properties of the current iteration (e.g., the current element, indices, etc.)
+    ///
+    /// Note: The caller is recommended to call `llvm.stacksave` and `llvm.stackrestore` before and
+    /// after invoking this function respectively. See [`NDIterType::construct`] for an explanation
+    /// on why this is suggested.
     pub fn foreach<'a, G, F>(
         &self,
         generator: &mut G,