diff --git a/nac3artiq/src/codegen.rs b/nac3artiq/src/codegen.rs
index 85f9b1c..1fcfd4b 100644
--- a/nac3artiq/src/codegen.rs
+++ b/nac3artiq/src/codegen.rs
@@ -461,7 +461,8 @@ fn format_rpc_arg<'ctx>(
             let (elem_ty, _) = unpack_ndarray_var_tys(&mut ctx.unifier, arg_ty);
             let llvm_elem_ty = ctx.get_llvm_type(generator, elem_ty);
             let llvm_arg_ty = NDArrayType::new(generator, ctx.ctx, llvm_elem_ty);
-            let llvm_arg = NDArrayValue::from_ptr_val(arg.into_pointer_value(), llvm_usize, None);
+            let llvm_arg =
+                NDArrayValue::from_pointer_value(arg.into_pointer_value(), llvm_usize, None);
 
             let llvm_usize_sizeof = ctx
                 .builder
@@ -1315,7 +1316,8 @@ fn polymorphic_print<'ctx>(
                 fmt.push('[');
                 flush(ctx, generator, &mut fmt, &mut args);
 
-                let val = ListValue::from_ptr_val(value.into_pointer_value(), llvm_usize, None);
+                let val =
+                    ListValue::from_pointer_value(value.into_pointer_value(), llvm_usize, None);
                 let len = val.load_size(ctx, None);
                 let last =
                     ctx.builder.build_int_sub(len, llvm_usize.const_int(1, false), "").unwrap();
@@ -1371,7 +1373,8 @@ fn polymorphic_print<'ctx>(
                 fmt.push_str("array([");
                 flush(ctx, generator, &mut fmt, &mut args);
 
-                let val = NDArrayValue::from_ptr_val(value.into_pointer_value(), llvm_usize, None);
+                let val =
+                    NDArrayValue::from_pointer_value(value.into_pointer_value(), llvm_usize, None);
                 let len = call_ndarray_calc_size(generator, ctx, &val.dim_sizes(), (None, None));
                 let last =
                     ctx.builder.build_int_sub(len, llvm_usize.const_int(1, false), "").unwrap();
@@ -1425,7 +1428,7 @@ fn polymorphic_print<'ctx>(
                 fmt.push_str("range(");
                 flush(ctx, generator, &mut fmt, &mut args);
 
-                let val = RangeValue::from_ptr_val(value.into_pointer_value(), None);
+                let val = RangeValue::from_pointer_value(value.into_pointer_value(), None);
 
                 let (start, stop, step) = destructure_range(ctx, val);
 
diff --git a/nac3core/src/codegen/builtin_fns.rs b/nac3core/src/codegen/builtin_fns.rs
index a6749d5..7765753 100644
--- a/nac3core/src/codegen/builtin_fns.rs
+++ b/nac3core/src/codegen/builtin_fns.rs
@@ -47,7 +47,7 @@ pub fn call_len<'ctx, G: CodeGenerator + ?Sized>(
     let (arg_ty, arg) = n;
 
     Ok(if ctx.unifier.unioned(arg_ty, range_ty) {
-        let arg = RangeValue::from_ptr_val(arg.into_pointer_value(), Some("range"));
+        let arg = RangeValue::from_pointer_value(arg.into_pointer_value(), Some("range"));
         let (start, end, step) = destructure_range(ctx, arg);
         calculate_len_for_slice_range(generator, ctx, start, end, step)
     } else {
@@ -67,7 +67,8 @@ pub fn call_len<'ctx, G: CodeGenerator + ?Sized>(
             TypeEnum::TObj { obj_id, .. } if *obj_id == PrimDef::NDArray.id() => {
                 let llvm_usize = generator.get_size_type(ctx.ctx);
 
-                let arg = NDArrayValue::from_ptr_val(arg.into_pointer_value(), llvm_usize, None);
+                let arg =
+                    NDArrayValue::from_pointer_value(arg.into_pointer_value(), llvm_usize, None);
 
                 let ndims = arg.dim_sizes().size(ctx, generator);
                 ctx.make_assert(
@@ -148,7 +149,7 @@ pub fn call_int32<'ctx, G: CodeGenerator + ?Sized>(
                 ctx,
                 ctx.primitives.int32,
                 None,
-                NDArrayValue::from_ptr_val(n, llvm_usize, None),
+                NDArrayValue::from_pointer_value(n, llvm_usize, None),
                 |generator, ctx, val| call_int32(generator, ctx, (elem_ty, val)),
             )?;
 
@@ -210,7 +211,7 @@ pub fn call_int64<'ctx, G: CodeGenerator + ?Sized>(
                 ctx,
                 ctx.primitives.int64,
                 None,
-                NDArrayValue::from_ptr_val(n, llvm_usize, None),
+                NDArrayValue::from_pointer_value(n, llvm_usize, None),
                 |generator, ctx, val| call_int64(generator, ctx, (elem_ty, val)),
             )?;
 
@@ -288,7 +289,7 @@ pub fn call_uint32<'ctx, G: CodeGenerator + ?Sized>(
                 ctx,
                 ctx.primitives.uint32,
                 None,
-                NDArrayValue::from_ptr_val(n, llvm_usize, None),
+                NDArrayValue::from_pointer_value(n, llvm_usize, None),
                 |generator, ctx, val| call_uint32(generator, ctx, (elem_ty, val)),
             )?;
 
@@ -355,7 +356,7 @@ pub fn call_uint64<'ctx, G: CodeGenerator + ?Sized>(
                 ctx,
                 ctx.primitives.uint64,
                 None,
-                NDArrayValue::from_ptr_val(n, llvm_usize, None),
+                NDArrayValue::from_pointer_value(n, llvm_usize, None),
                 |generator, ctx, val| call_uint64(generator, ctx, (elem_ty, val)),
             )?;
 
@@ -421,7 +422,7 @@ pub fn call_float<'ctx, G: CodeGenerator + ?Sized>(
                 ctx,
                 ctx.primitives.float,
                 None,
-                NDArrayValue::from_ptr_val(n, llvm_usize, None),
+                NDArrayValue::from_pointer_value(n, llvm_usize, None),
                 |generator, ctx, val| call_float(generator, ctx, (elem_ty, val)),
             )?;
 
@@ -467,7 +468,7 @@ pub fn call_round<'ctx, G: CodeGenerator + ?Sized>(
                 ctx,
                 ret_elem_ty,
                 None,
-                NDArrayValue::from_ptr_val(n, llvm_usize, None),
+                NDArrayValue::from_pointer_value(n, llvm_usize, None),
                 |generator, ctx, val| call_round(generator, ctx, (elem_ty, val), ret_elem_ty),
             )?;
 
@@ -507,7 +508,7 @@ pub fn call_numpy_round<'ctx, G: CodeGenerator + ?Sized>(
                 ctx,
                 ctx.primitives.float,
                 None,
-                NDArrayValue::from_ptr_val(n, llvm_usize, None),
+                NDArrayValue::from_pointer_value(n, llvm_usize, None),
                 |generator, ctx, val| call_numpy_round(generator, ctx, (elem_ty, val)),
             )?;
 
@@ -572,7 +573,7 @@ pub fn call_bool<'ctx, G: CodeGenerator + ?Sized>(
                 ctx,
                 ctx.primitives.bool,
                 None,
-                NDArrayValue::from_ptr_val(n, llvm_usize, None),
+                NDArrayValue::from_pointer_value(n, llvm_usize, None),
                 |generator, ctx, val| {
                     let elem = call_bool(generator, ctx, (elem_ty, val))?;
 
@@ -626,7 +627,7 @@ pub fn call_floor<'ctx, G: CodeGenerator + ?Sized>(
                 ctx,
                 ret_elem_ty,
                 None,
-                NDArrayValue::from_ptr_val(n, llvm_usize, None),
+                NDArrayValue::from_pointer_value(n, llvm_usize, None),
                 |generator, ctx, val| call_floor(generator, ctx, (elem_ty, val), ret_elem_ty),
             )?;
 
@@ -676,7 +677,7 @@ pub fn call_ceil<'ctx, G: CodeGenerator + ?Sized>(
                 ctx,
                 ret_elem_ty,
                 None,
-                NDArrayValue::from_ptr_val(n, llvm_usize, None),
+                NDArrayValue::from_pointer_value(n, llvm_usize, None),
                 |generator, ctx, val| call_ceil(generator, ctx, (elem_ty, val), ret_elem_ty),
             )?;
 
@@ -907,7 +908,7 @@ pub fn call_numpy_max_min<'ctx, G: CodeGenerator + ?Sized>(
             let (elem_ty, _) = unpack_ndarray_var_tys(&mut ctx.unifier, a_ty);
             let llvm_ndarray_ty = ctx.get_llvm_type(generator, elem_ty);
 
-            let n = NDArrayValue::from_ptr_val(n, llvm_usize, None);
+            let n = NDArrayValue::from_pointer_value(n, llvm_usize, None);
             let n_sz = irrt::call_ndarray_calc_size(generator, ctx, &n.dim_sizes(), (None, None));
             if ctx.registry.llvm_options.opt_level == OptimizationLevel::None {
                 let n_sz_eqz = ctx
@@ -1120,7 +1121,7 @@ where
                 ctx,
                 ret_elem_ty,
                 None,
-                NDArrayValue::from_ptr_val(x, llvm_usize, None),
+                NDArrayValue::from_pointer_value(x, llvm_usize, None),
                 |generator, ctx, elem_val| {
                     helper_call_numpy_unary_elementwise(
                         generator,
@@ -1959,7 +1960,7 @@ pub fn call_np_linalg_cholesky<'ctx, G: CodeGenerator + ?Sized>(
             unsupported_type(ctx, FN_NAME, &[x1_ty]);
         };
 
-        let n1 = NDArrayValue::from_ptr_val(n1, llvm_usize, None);
+        let n1 = NDArrayValue::from_pointer_value(n1, llvm_usize, None);
         let dim0 = unsafe {
             n1.dim_sizes()
                 .get_unchecked(ctx, generator, &llvm_usize.const_zero(), None)
@@ -2001,7 +2002,7 @@ pub fn call_np_linalg_qr<'ctx, G: CodeGenerator + ?Sized>(
             unimplemented!("{FN_NAME} operates on float type NdArrays only");
         };
 
-        let n1 = NDArrayValue::from_ptr_val(n1, llvm_usize, None);
+        let n1 = NDArrayValue::from_pointer_value(n1, llvm_usize, None);
         let dim0 = unsafe {
             n1.dim_sizes()
                 .get_unchecked(ctx, generator, &llvm_usize.const_zero(), None)
@@ -2051,7 +2052,7 @@ pub fn call_np_linalg_svd<'ctx, G: CodeGenerator + ?Sized>(
             unsupported_type(ctx, FN_NAME, &[x1_ty]);
         };
 
-        let n1 = NDArrayValue::from_ptr_val(n1, llvm_usize, None);
+        let n1 = NDArrayValue::from_pointer_value(n1, llvm_usize, None);
 
         let dim0 = unsafe {
             n1.dim_sizes()
@@ -2106,7 +2107,7 @@ pub fn call_np_linalg_inv<'ctx, G: CodeGenerator + ?Sized>(
             unsupported_type(ctx, FN_NAME, &[x1_ty]);
         };
 
-        let n1 = NDArrayValue::from_ptr_val(n1, llvm_usize, None);
+        let n1 = NDArrayValue::from_pointer_value(n1, llvm_usize, None);
         let dim0 = unsafe {
             n1.dim_sizes()
                 .get_unchecked(ctx, generator, &llvm_usize.const_zero(), None)
@@ -2148,7 +2149,7 @@ pub fn call_np_linalg_pinv<'ctx, G: CodeGenerator + ?Sized>(
             unsupported_type(ctx, FN_NAME, &[x1_ty]);
         };
 
-        let n1 = NDArrayValue::from_ptr_val(n1, llvm_usize, None);
+        let n1 = NDArrayValue::from_pointer_value(n1, llvm_usize, None);
 
         let dim0 = unsafe {
             n1.dim_sizes()
@@ -2191,7 +2192,7 @@ pub fn call_sp_linalg_lu<'ctx, G: CodeGenerator + ?Sized>(
             unsupported_type(ctx, FN_NAME, &[x1_ty]);
         };
 
-        let n1 = NDArrayValue::from_ptr_val(n1, llvm_usize, None);
+        let n1 = NDArrayValue::from_pointer_value(n1, llvm_usize, None);
 
         let dim0 = unsafe {
             n1.dim_sizes()
@@ -2244,7 +2245,7 @@ pub fn call_np_linalg_matrix_power<'ctx, G: CodeGenerator + ?Sized>(
             unsupported_type(ctx, FN_NAME, &[x1_ty, x2_ty]);
         };
 
-        let n1 = NDArrayValue::from_ptr_val(n1, llvm_usize, None);
+        let n1 = NDArrayValue::from_pointer_value(n1, llvm_usize, None);
         // Changing second parameter to a `NDArray` for uniformity in function call
         let n2_array = numpy::create_ndarray_const_shape(
             generator,
@@ -2339,7 +2340,7 @@ pub fn call_sp_linalg_schur<'ctx, G: CodeGenerator + ?Sized>(
             unsupported_type(ctx, FN_NAME, &[x1_ty]);
         };
 
-        let n1 = NDArrayValue::from_ptr_val(n1, llvm_usize, None);
+        let n1 = NDArrayValue::from_pointer_value(n1, llvm_usize, None);
 
         let dim0 = unsafe {
             n1.dim_sizes()
@@ -2382,7 +2383,7 @@ pub fn call_sp_linalg_hessenberg<'ctx, G: CodeGenerator + ?Sized>(
             unsupported_type(ctx, FN_NAME, &[x1_ty]);
         };
 
-        let n1 = NDArrayValue::from_ptr_val(n1, llvm_usize, None);
+        let n1 = NDArrayValue::from_pointer_value(n1, llvm_usize, None);
 
         let dim0 = unsafe {
             n1.dim_sizes()
diff --git a/nac3core/src/codegen/expr.rs b/nac3core/src/codegen/expr.rs
index 7584826..93720f9 100644
--- a/nac3core/src/codegen/expr.rs
+++ b/nac3core/src/codegen/expr.rs
@@ -1168,7 +1168,8 @@ pub fn gen_comprehension<'ctx, G: CodeGenerator>(
         TypeEnum::TObj { obj_id, .. }
             if *obj_id == ctx.primitives.range.obj_id(&ctx.unifier).unwrap() =>
         {
-            let iter_val = RangeValue::from_ptr_val(iter_val.into_pointer_value(), Some("range"));
+            let iter_val =
+                RangeValue::from_pointer_value(iter_val.into_pointer_value(), Some("range"));
             let (start, stop, step) = destructure_range(ctx, iter_val);
             let diff = ctx.builder.build_int_sub(stop, start, "diff").unwrap();
             // add 1 to the length as the value is rounded to zero
@@ -1399,8 +1400,10 @@ pub fn gen_binop_expr_with_values<'ctx, G: CodeGenerator>(
                 let llvm_elem_ty = ctx.get_llvm_type(generator, elem_ty1);
                 let sizeof_elem = llvm_elem_ty.size_of().unwrap();
 
-                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);
+                let lhs =
+                    ListValue::from_pointer_value(left_val.into_pointer_value(), llvm_usize, None);
+                let rhs =
+                    ListValue::from_pointer_value(right_val.into_pointer_value(), llvm_usize, None);
 
                 let size = ctx
                     .builder
@@ -1483,7 +1486,7 @@ pub fn gen_binop_expr_with_values<'ctx, G: CodeGenerator>(
                         codegen_unreachable!(ctx)
                     };
                 let list_val =
-                    ListValue::from_ptr_val(list_val.into_pointer_value(), llvm_usize, None);
+                    ListValue::from_pointer_value(list_val.into_pointer_value(), llvm_usize, None);
                 let int_val = ctx
                     .builder
                     .build_int_s_extend(int_val.into_int_value(), llvm_usize, "")
@@ -1562,9 +1565,9 @@ pub fn gen_binop_expr_with_values<'ctx, G: CodeGenerator>(
             assert!(ctx.unifier.unioned(ndarray_dtype1, ndarray_dtype2));
 
             let left_val =
-                NDArrayValue::from_ptr_val(left_val.into_pointer_value(), llvm_usize, None);
+                NDArrayValue::from_pointer_value(left_val.into_pointer_value(), llvm_usize, None);
             let right_val =
-                NDArrayValue::from_ptr_val(right_val.into_pointer_value(), llvm_usize, None);
+                NDArrayValue::from_pointer_value(right_val.into_pointer_value(), llvm_usize, None);
 
             let res = if op.base == Operator::MatMult {
                 // MatMult is the only binop which is not an elementwise op
@@ -1613,7 +1616,7 @@ pub fn gen_binop_expr_with_values<'ctx, G: CodeGenerator>(
         } else {
             let (ndarray_dtype, _) =
                 unpack_ndarray_var_tys(&mut ctx.unifier, if is_ndarray1 { ty1 } else { ty2 });
-            let ndarray_val = NDArrayValue::from_ptr_val(
+            let ndarray_val = NDArrayValue::from_pointer_value(
                 if is_ndarray1 { left_val } else { right_val }.into_pointer_value(),
                 llvm_usize,
                 None,
@@ -1808,7 +1811,7 @@ pub fn gen_unaryop_expr_with_values<'ctx, G: CodeGenerator>(
         let llvm_usize = generator.get_size_type(ctx.ctx);
         let (ndarray_dtype, _) = unpack_ndarray_var_tys(&mut ctx.unifier, ty);
 
-        let val = NDArrayValue::from_ptr_val(val.into_pointer_value(), llvm_usize, None);
+        let val = NDArrayValue::from_pointer_value(val.into_pointer_value(), llvm_usize, None);
 
         // ndarray uses `~` rather than `not` to perform elementwise inversion, convert it before
         // passing it to the elementwise codegen function
@@ -1900,7 +1903,7 @@ pub fn gen_cmpop_expr_with_values<'ctx, G: CodeGenerator>(
                 assert!(ctx.unifier.unioned(ndarray_dtype1, ndarray_dtype2));
 
                 let left_val =
-                    NDArrayValue::from_ptr_val(lhs.into_pointer_value(), llvm_usize, None);
+                    NDArrayValue::from_pointer_value(lhs.into_pointer_value(), llvm_usize, None);
                 let res = numpy::ndarray_elementwise_binop_impl(
                     generator,
                     ctx,
@@ -2202,9 +2205,9 @@ pub fn gen_cmpop_expr_with_values<'ctx, G: CodeGenerator>(
                     }
 
                     let left_val =
-                        ListValue::from_ptr_val(lhs.into_pointer_value(), llvm_usize, None);
+                        ListValue::from_pointer_value(lhs.into_pointer_value(), llvm_usize, None);
                     let right_val =
-                        ListValue::from_ptr_val(rhs.into_pointer_value(), llvm_usize, None);
+                        ListValue::from_pointer_value(rhs.into_pointer_value(), llvm_usize, None);
 
                     Ok(gen_if_else_expr_callback(
                         generator,
@@ -2768,7 +2771,8 @@ fn gen_ndarray_subscript_expr<'ctx, G: CodeGenerator>(
                 // elements over
                 let subscripted_ndarray =
                     generator.gen_var_alloc(ctx, llvm_ndarray_t.into(), None)?;
-                let ndarray = NDArrayValue::from_ptr_val(subscripted_ndarray, llvm_usize, None);
+                let ndarray =
+                    NDArrayValue::from_pointer_value(subscripted_ndarray, llvm_usize, None);
 
                 let num_dims = v.load_ndims(ctx);
                 ndarray.store_ndims(
@@ -3403,7 +3407,7 @@ pub fn gen_expr<'ctx, G: CodeGenerator>(
                     } else {
                         return Ok(None);
                     };
-                    let v = ListValue::from_ptr_val(v, usize, Some("arr"));
+                    let v = ListValue::from_pointer_value(v, usize, Some("arr"));
                     let ty = ctx.get_llvm_type(generator, *ty);
                     if let ExprKind::Slice { lower, upper, step } = &slice.node {
                         let one = int32.const_int(1, false);
@@ -3513,7 +3517,7 @@ pub fn gen_expr<'ctx, G: CodeGenerator>(
                     } else {
                         return Ok(None);
                     };
-                    let v = NDArrayValue::from_ptr_val(v, usize, None);
+                    let v = NDArrayValue::from_pointer_value(v, usize, None);
 
                     return gen_ndarray_subscript_expr(generator, ctx, *ty, *ndims, v, slice);
                 }
diff --git a/nac3core/src/codegen/numpy.rs b/nac3core/src/codegen/numpy.rs
index 538809c..4589ba4 100644
--- a/nac3core/src/codegen/numpy.rs
+++ b/nac3core/src/codegen/numpy.rs
@@ -54,7 +54,7 @@ fn create_ndarray_uninitialized<'ctx, G: CodeGenerator + ?Sized>(
 
     let ndarray = generator.gen_var_alloc(ctx, llvm_ndarray_t.into(), None)?;
 
-    Ok(NDArrayValue::from_ptr_val(ndarray, llvm_usize, None))
+    Ok(NDArrayValue::from_pointer_value(ndarray, llvm_usize, None))
 }
 
 /// Creates an `NDArray` instance from a dynamic shape.
@@ -314,11 +314,11 @@ fn call_ndarray_empty_impl<'ctx, G: CodeGenerator + ?Sized>(
 
     match shape {
         BasicValueEnum::PointerValue(shape_list_ptr)
-            if ListValue::is_instance(shape_list_ptr, llvm_usize).is_ok() =>
+            if ListValue::is_representable(shape_list_ptr, llvm_usize).is_ok() =>
         {
             // 1. A list of ints; e.g., `np.empty([600, 800, 3])`
 
-            let shape_list = ListValue::from_ptr_val(shape_list_ptr, llvm_usize, None);
+            let shape_list = ListValue::from_pointer_value(shape_list_ptr, llvm_usize, None);
             create_ndarray_dyn_shape(
                 generator,
                 ctx,
@@ -499,12 +499,14 @@ where
 
     // Assert that all ndarray operands are broadcastable to the target size
     if !lhs_scalar {
-        let lhs_val = NDArrayValue::from_ptr_val(lhs_val.into_pointer_value(), llvm_usize, None);
+        let lhs_val =
+            NDArrayValue::from_pointer_value(lhs_val.into_pointer_value(), llvm_usize, None);
         ndarray_assert_is_broadcastable(generator, ctx, res, lhs_val);
     }
 
     if !rhs_scalar {
-        let rhs_val = NDArrayValue::from_ptr_val(rhs_val.into_pointer_value(), llvm_usize, None);
+        let rhs_val =
+            NDArrayValue::from_pointer_value(rhs_val.into_pointer_value(), llvm_usize, None);
         ndarray_assert_is_broadcastable(generator, ctx, res, rhs_val);
     }
 
@@ -512,7 +514,8 @@ where
         let lhs_elem = if lhs_scalar {
             lhs_val
         } else {
-            let lhs = NDArrayValue::from_ptr_val(lhs_val.into_pointer_value(), llvm_usize, None);
+            let lhs =
+                NDArrayValue::from_pointer_value(lhs_val.into_pointer_value(), llvm_usize, None);
             let lhs_idx = call_ndarray_calc_broadcast_index(generator, ctx, lhs, idx);
 
             unsafe { lhs.data().get_unchecked(ctx, generator, &lhs_idx, None) }
@@ -521,7 +524,8 @@ where
         let rhs_elem = if rhs_scalar {
             rhs_val
         } else {
-            let rhs = NDArrayValue::from_ptr_val(rhs_val.into_pointer_value(), llvm_usize, None);
+            let rhs =
+                NDArrayValue::from_pointer_value(rhs_val.into_pointer_value(), llvm_usize, None);
             let rhs_idx = call_ndarray_calc_broadcast_index(generator, ctx, rhs, idx);
 
             unsafe { rhs.data().get_unchecked(ctx, generator, &rhs_idx, None) }
@@ -647,11 +651,15 @@ fn llvm_ndlist_get_ndims<'ctx, G: CodeGenerator + ?Sized>(
 
     let ndims = llvm_usize.const_int(1, false);
     match list_elem_ty {
-        AnyTypeEnum::PointerType(ptr_ty) if ListType::is_type(ptr_ty, llvm_usize).is_ok() => {
+        AnyTypeEnum::PointerType(ptr_ty)
+            if ListType::is_representable(ptr_ty, llvm_usize).is_ok() =>
+        {
             ndims.const_add(llvm_ndlist_get_ndims(generator, ctx, ptr_ty))
         }
 
-        AnyTypeEnum::PointerType(ptr_ty) if NDArrayType::is_type(ptr_ty, llvm_usize).is_ok() => {
+        AnyTypeEnum::PointerType(ptr_ty)
+            if NDArrayType::is_representable(ptr_ty, llvm_usize).is_ok() =>
+        {
             todo!("Getting ndims for list[ndarray] not supported")
         }
 
@@ -668,11 +676,13 @@ fn llvm_arraylike_get_ndims<'ctx, G: CodeGenerator + ?Sized>(
     let llvm_usize = generator.get_size_type(ctx.ctx);
 
     match value {
-        BasicValueEnum::PointerValue(v) if NDArrayValue::is_instance(v, llvm_usize).is_ok() => {
-            NDArrayValue::from_ptr_val(v, llvm_usize, None).load_ndims(ctx)
+        BasicValueEnum::PointerValue(v)
+            if NDArrayValue::is_representable(v, llvm_usize).is_ok() =>
+        {
+            NDArrayValue::from_pointer_value(v, llvm_usize, None).load_ndims(ctx)
         }
 
-        BasicValueEnum::PointerValue(v) if ListValue::is_instance(v, llvm_usize).is_ok() => {
+        BasicValueEnum::PointerValue(v) if ListValue::is_representable(v, llvm_usize).is_ok() => {
             llvm_ndlist_get_ndims(generator, ctx, v.get_type())
         }
 
@@ -695,7 +705,9 @@ fn ndarray_from_ndlist_impl<'ctx, G: CodeGenerator + ?Sized>(
     let list_elem_ty = src_lst.get_type().element_type();
 
     match list_elem_ty {
-        AnyTypeEnum::PointerType(ptr_ty) if ListType::is_type(ptr_ty, llvm_usize).is_ok() => {
+        AnyTypeEnum::PointerType(ptr_ty)
+            if ListType::is_representable(ptr_ty, llvm_usize).is_ok() =>
+        {
             // The stride of elements in this dimension, i.e. the number of elements between arr[i]
             // and arr[i + 1] in this dimension
             let stride = call_ndarray_calc_size(
@@ -719,7 +731,7 @@ fn ndarray_from_ndlist_impl<'ctx, G: CodeGenerator + ?Sized>(
                     let dst_ptr =
                         unsafe { ctx.builder.build_gep(dst_slice_ptr, &[offset], "").unwrap() };
 
-                    let nested_lst_elem = ListValue::from_ptr_val(
+                    let nested_lst_elem = ListValue::from_pointer_value(
                         unsafe { src_lst.data().get_unchecked(ctx, generator, &i, None) }
                             .into_pointer_value(),
                         llvm_usize,
@@ -740,7 +752,9 @@ fn ndarray_from_ndlist_impl<'ctx, G: CodeGenerator + ?Sized>(
             )?;
         }
 
-        AnyTypeEnum::PointerType(ptr_ty) if NDArrayType::is_type(ptr_ty, llvm_usize).is_ok() => {
+        AnyTypeEnum::PointerType(ptr_ty)
+            if NDArrayType::is_representable(ptr_ty, llvm_usize).is_ok() =>
+        {
             todo!("Not implemented for list[ndarray]")
         }
 
@@ -801,8 +815,8 @@ fn call_ndarray_array_impl<'ctx, G: CodeGenerator + ?Sized>(
     let object = object.into_pointer_value();
 
     // object is an NDArray instance - copy object unless copy=0 && ndmin < object.ndims
-    if NDArrayValue::is_instance(object, llvm_usize).is_ok() {
-        let object = NDArrayValue::from_ptr_val(object, llvm_usize, None);
+    if NDArrayValue::is_representable(object, llvm_usize).is_ok() {
+        let object = NDArrayValue::from_pointer_value(object, llvm_usize, None);
 
         let ndarray = gen_if_else_expr_callback(
             generator,
@@ -876,7 +890,7 @@ fn call_ndarray_array_impl<'ctx, G: CodeGenerator + ?Sized>(
             |_, _| Ok(Some(object.as_base_value())),
         )?;
 
-        return Ok(NDArrayValue::from_ptr_val(
+        return Ok(NDArrayValue::from_pointer_value(
             ndarray.map(BasicValueEnum::into_pointer_value).unwrap(),
             llvm_usize,
             None,
@@ -884,8 +898,8 @@ fn call_ndarray_array_impl<'ctx, G: CodeGenerator + ?Sized>(
     }
 
     // Remaining case: TList
-    assert!(ListValue::is_instance(object, llvm_usize).is_ok());
-    let object = ListValue::from_ptr_val(object, llvm_usize, None);
+    assert!(ListValue::is_representable(object, llvm_usize).is_ok());
+    let object = ListValue::from_pointer_value(object, llvm_usize, None);
 
     // The number of dimensions to prepend 1's to
     let ndims = llvm_ndlist_get_ndims(generator, ctx, object.as_base_value().get_type());
@@ -965,7 +979,8 @@ fn call_ndarray_array_impl<'ctx, G: CodeGenerator + ?Sized>(
                                 .map(|v| ctx.builder.build_bit_cast(v, plist_plist_i8, "").unwrap())
                                 .map(BasicValueEnum::into_pointer_value)
                                 .unwrap();
-                            let this_dim = ListValue::from_ptr_val(this_dim, llvm_usize, None);
+                            let this_dim =
+                                ListValue::from_pointer_value(this_dim, llvm_usize, None);
 
                             // TODO: Assert this_dim.sz != 0
 
@@ -991,7 +1006,7 @@ fn call_ndarray_array_impl<'ctx, G: CodeGenerator + ?Sized>(
                         },
                     )?;
 
-                    let lst = ListValue::from_ptr_val(
+                    let lst = ListValue::from_pointer_value(
                         ctx.builder
                             .build_load(lst, "")
                             .map(BasicValueEnum::into_pointer_value)
@@ -1388,9 +1403,9 @@ where
     let ndarray = res.unwrap_or_else(|| {
         if lhs_scalar && rhs_scalar {
             let lhs_val =
-                NDArrayValue::from_ptr_val(lhs_val.into_pointer_value(), llvm_usize, None);
+                NDArrayValue::from_pointer_value(lhs_val.into_pointer_value(), llvm_usize, None);
             let rhs_val =
-                NDArrayValue::from_ptr_val(rhs_val.into_pointer_value(), llvm_usize, None);
+                NDArrayValue::from_pointer_value(rhs_val.into_pointer_value(), llvm_usize, None);
 
             let ndarray_dims = call_ndarray_calc_broadcast(generator, ctx, lhs_val, rhs_val);
 
@@ -1406,7 +1421,7 @@ where
             )
             .unwrap()
         } else {
-            let ndarray = NDArrayValue::from_ptr_val(
+            let ndarray = NDArrayValue::from_pointer_value(
                 if lhs_scalar { rhs_val } else { lhs_val }.into_pointer_value(),
                 llvm_usize,
                 None,
@@ -1970,7 +1985,7 @@ pub fn gen_ndarray_copy<'ctx>(
         generator,
         context,
         this_elem_ty,
-        NDArrayValue::from_ptr_val(this_arg.into_pointer_value(), llvm_usize, None),
+        NDArrayValue::from_pointer_value(this_arg.into_pointer_value(), llvm_usize, None),
     )
     .map(NDArrayValue::into)
 }
@@ -2002,7 +2017,7 @@ pub fn gen_ndarray_fill<'ctx>(
     ndarray_fill_flattened(
         generator,
         context,
-        NDArrayValue::from_ptr_val(this_arg, llvm_usize, None),
+        NDArrayValue::from_pointer_value(this_arg, llvm_usize, None),
         |generator, ctx, _| {
             let value = if value_arg.is_pointer_value() {
                 let llvm_i1 = ctx.ctx.bool_type();
@@ -2043,7 +2058,7 @@ pub fn ndarray_transpose<'ctx, G: CodeGenerator + ?Sized>(
 
     if let BasicValueEnum::PointerValue(n1) = x1 {
         let (elem_ty, _) = unpack_ndarray_var_tys(&mut ctx.unifier, x1_ty);
-        let n1 = NDArrayValue::from_ptr_val(n1, llvm_usize, None);
+        let n1 = NDArrayValue::from_pointer_value(n1, llvm_usize, None);
         let n_sz = call_ndarray_calc_size(generator, ctx, &n1.dim_sizes(), (None, None));
 
         // Dimensions are reversed in the transposed array
@@ -2162,7 +2177,7 @@ pub fn ndarray_reshape<'ctx, G: CodeGenerator + ?Sized>(
 
     if let BasicValueEnum::PointerValue(n1) = x1 {
         let (elem_ty, _) = unpack_ndarray_var_tys(&mut ctx.unifier, x1_ty);
-        let n1 = NDArrayValue::from_ptr_val(n1, llvm_usize, None);
+        let n1 = NDArrayValue::from_pointer_value(n1, llvm_usize, None);
         let n_sz = call_ndarray_calc_size(generator, ctx, &n1.dim_sizes(), (None, None));
 
         let acc = generator.gen_var_alloc(ctx, llvm_usize.into(), None)?;
@@ -2172,11 +2187,11 @@ pub fn ndarray_reshape<'ctx, G: CodeGenerator + ?Sized>(
 
         let out = match shape {
             BasicValueEnum::PointerValue(shape_list_ptr)
-                if ListValue::is_instance(shape_list_ptr, llvm_usize).is_ok() =>
+                if ListValue::is_representable(shape_list_ptr, llvm_usize).is_ok() =>
             {
                 // 1. A list of ints; e.g., `np.reshape(arr, [int64(600), int64(800, -1])`
 
-                let shape_list = ListValue::from_ptr_val(shape_list_ptr, llvm_usize, None);
+                let shape_list = ListValue::from_pointer_value(shape_list_ptr, llvm_usize, None);
                 // Check for -1 in dimensions
                 gen_for_callback_incrementing(
                     generator,
@@ -2445,8 +2460,8 @@ pub fn ndarray_dot<'ctx, G: CodeGenerator + ?Sized>(
 
     match (x1, x2) {
         (BasicValueEnum::PointerValue(n1), BasicValueEnum::PointerValue(n2)) => {
-            let n1 = NDArrayValue::from_ptr_val(n1, llvm_usize, None);
-            let n2 = NDArrayValue::from_ptr_val(n2, llvm_usize, None);
+            let n1 = NDArrayValue::from_pointer_value(n1, llvm_usize, None);
+            let n2 = NDArrayValue::from_pointer_value(n2, llvm_usize, None);
 
             let n1_sz = call_ndarray_calc_size(generator, ctx, &n1.dim_sizes(), (None, None));
             let n2_sz = call_ndarray_calc_size(generator, ctx, &n1.dim_sizes(), (None, None));
diff --git a/nac3core/src/codegen/stmt.rs b/nac3core/src/codegen/stmt.rs
index d008f7b..3595528 100644
--- a/nac3core/src/codegen/stmt.rs
+++ b/nac3core/src/codegen/stmt.rs
@@ -310,7 +310,7 @@ pub fn gen_setitem<'ctx, G: CodeGenerator>(
                 .unwrap()
                 .to_basic_value_enum(ctx, generator, target_ty)?
                 .into_pointer_value();
-            let target = ListValue::from_ptr_val(target, llvm_usize, None);
+            let target = ListValue::from_pointer_value(target, llvm_usize, None);
 
             if let ExprKind::Slice { .. } = &key.node {
                 // Handle assigning to a slice
@@ -331,7 +331,7 @@ pub fn gen_setitem<'ctx, G: CodeGenerator>(
 
                 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 = ListValue::from_pointer_value(value, llvm_usize, None);
 
                 let target_item_ty = ctx.get_llvm_type(generator, target_item_ty);
                 let Some(src_ind) = handle_slice_indices(
@@ -463,7 +463,8 @@ pub fn gen_for<G: CodeGenerator>(
         TypeEnum::TObj { obj_id, .. }
             if *obj_id == ctx.primitives.range.obj_id(&ctx.unifier).unwrap() =>
         {
-            let iter_val = RangeValue::from_ptr_val(iter_val.into_pointer_value(), Some("range"));
+            let iter_val =
+                RangeValue::from_pointer_value(iter_val.into_pointer_value(), Some("range"));
             // Internal variable for loop; Cannot be assigned
             let i = generator.gen_var_alloc(ctx, int32.into(), Some("for.i.addr"))?;
             // Variable declared in "target" expression of the loop; Can be reassigned *or* shadowed
diff --git a/nac3core/src/codegen/test.rs b/nac3core/src/codegen/test.rs
index 5dd6070..a1c391a 100644
--- a/nac3core/src/codegen/test.rs
+++ b/nac3core/src/codegen/test.rs
@@ -452,7 +452,7 @@ fn test_classes_list_type_new() {
     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());
+    assert!(ListType::is_representable(llvm_list.as_base_type(), llvm_usize).is_ok());
 }
 
 #[test]
@@ -460,7 +460,7 @@ fn test_classes_range_type_new() {
     let ctx = inkwell::context::Context::create();
 
     let llvm_range = RangeType::new(&ctx);
-    assert!(RangeType::is_type(llvm_range.as_base_type()).is_ok());
+    assert!(RangeType::is_representable(llvm_range.as_base_type()).is_ok());
 }
 
 #[test]
@@ -472,5 +472,5 @@ fn test_classes_ndarray_type_new() {
     let llvm_usize = generator.get_size_type(&ctx);
 
     let llvm_ndarray = NDArrayType::new(&generator, &ctx, llvm_i32.into());
-    assert!(NDArrayType::is_type(llvm_ndarray.as_base_type(), llvm_usize).is_ok());
+    assert!(NDArrayType::is_representable(llvm_ndarray.as_base_type(), llvm_usize).is_ok());
 }
diff --git a/nac3core/src/codegen/types/list.rs b/nac3core/src/codegen/types/list.rs
index c68e4ab..4561b48 100644
--- a/nac3core/src/codegen/types/list.rs
+++ b/nac3core/src/codegen/types/list.rs
@@ -20,7 +20,10 @@ pub struct ListType<'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> {
+    pub fn is_representable(
+        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}"));
@@ -73,7 +76,7 @@ impl<'ctx> ListType<'ctx> {
     /// 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());
+        debug_assert!(Self::is_representable(ptr_ty, llvm_usize).is_ok());
 
         ListType { ty: ptr_ty, llvm_usize }
     }
@@ -106,6 +109,26 @@ impl<'ctx> ProxyType<'ctx> for ListType<'ctx> {
     type Base = PointerType<'ctx>;
     type Value = ListValue<'ctx>;
 
+    fn is_type<G: CodeGenerator + ?Sized>(
+        generator: &G,
+        ctx: &'ctx Context,
+        llvm_ty: impl BasicType<'ctx>,
+    ) -> Result<(), String> {
+        if let BasicTypeEnum::PointerType(ty) = llvm_ty.as_basic_type_enum() {
+            <Self as ProxyType<'ctx>>::is_representable(generator, ctx, ty)
+        } else {
+            Err(format!("Expected pointer type, got {llvm_ty:?}"))
+        }
+    }
+
+    fn is_representable<G: CodeGenerator + ?Sized>(
+        generator: &G,
+        ctx: &'ctx Context,
+        llvm_ty: Self::Base,
+    ) -> Result<(), String> {
+        Self::is_representable(llvm_ty, generator.get_size_type(ctx))
+    }
+
     fn new_value<G: CodeGenerator + ?Sized>(
         &self,
         generator: &mut G,
@@ -146,9 +169,7 @@ impl<'ctx> ProxyType<'ctx> for ListType<'ctx> {
         value: <Self::Value as ProxyValue<'ctx>>::Base,
         name: Option<&'ctx str>,
     ) -> Self::Value {
-        debug_assert_eq!(value.get_type(), self.as_base_type());
-
-        ListValue::from_ptr_val(value, self.llvm_usize, name)
+        Self::Value::from_pointer_value(value, self.llvm_usize, name)
     }
 
     fn as_base_type(&self) -> Self::Base {
diff --git a/nac3core/src/codegen/types/mod.rs b/nac3core/src/codegen/types/mod.rs
index 6032936..ab3d46b 100644
--- a/nac3core/src/codegen/types/mod.rs
+++ b/nac3core/src/codegen/types/mod.rs
@@ -1,4 +1,4 @@
-use inkwell::{types::BasicType, values::IntValue};
+use inkwell::{context::Context, types::BasicType, values::IntValue};
 
 use super::{
     values::{ArraySliceValue, ProxyValue},
@@ -19,7 +19,20 @@ pub trait ProxyType<'ctx>: Into<Self::Base> {
     type Base: BasicType<'ctx>;
 
     /// The type of values represented by this type.
-    type Value: ProxyValue<'ctx>;
+    type Value: ProxyValue<'ctx, Type = Self>;
+
+    fn is_type<G: CodeGenerator + ?Sized>(
+        generator: &G,
+        ctx: &'ctx Context,
+        llvm_ty: impl BasicType<'ctx>,
+    ) -> Result<(), String>;
+
+    /// Checks whether `llvm_ty` can be represented by this [`ProxyType`].
+    fn is_representable<G: CodeGenerator + ?Sized>(
+        generator: &G,
+        ctx: &'ctx Context,
+        llvm_ty: Self::Base,
+    ) -> Result<(), String>;
 
     /// Creates a new value of this type.
     fn new_value<G: CodeGenerator + ?Sized>(
diff --git a/nac3core/src/codegen/types/ndarray.rs b/nac3core/src/codegen/types/ndarray.rs
index 780a7a6..ca463b6 100644
--- a/nac3core/src/codegen/types/ndarray.rs
+++ b/nac3core/src/codegen/types/ndarray.rs
@@ -20,7 +20,10 @@ pub struct NDArrayType<'ctx> {
 
 impl<'ctx> NDArrayType<'ctx> {
     /// Checks whether `llvm_ty` represents a `ndarray` type, returning [Err] if it does not.
-    pub fn is_type(llvm_ty: PointerType<'ctx>, llvm_usize: IntType<'ctx>) -> Result<(), String> {
+    pub fn is_representable(
+        llvm_ty: PointerType<'ctx>,
+        llvm_usize: IntType<'ctx>,
+    ) -> Result<(), String> {
         let llvm_ndarray_ty = llvm_ty.get_element_type();
         let AnyTypeEnum::StructType(llvm_ndarray_ty) = llvm_ndarray_ty else {
             return Err(format!("Expected struct type for `NDArray` type, got {llvm_ndarray_ty}"));
@@ -101,7 +104,7 @@ impl<'ctx> NDArrayType<'ctx> {
     /// Creates an [`NDArrayType`] 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());
+        debug_assert!(Self::is_representable(ptr_ty, llvm_usize).is_ok());
 
         NDArrayType { ty: ptr_ty, llvm_usize }
     }
@@ -134,6 +137,26 @@ impl<'ctx> ProxyType<'ctx> for NDArrayType<'ctx> {
     type Base = PointerType<'ctx>;
     type Value = NDArrayValue<'ctx>;
 
+    fn is_type<G: CodeGenerator + ?Sized>(
+        generator: &G,
+        ctx: &'ctx Context,
+        llvm_ty: impl BasicType<'ctx>,
+    ) -> Result<(), String> {
+        if let BasicTypeEnum::PointerType(ty) = llvm_ty.as_basic_type_enum() {
+            <Self as ProxyType<'ctx>>::is_representable(generator, ctx, ty)
+        } else {
+            Err(format!("Expected pointer type, got {llvm_ty:?}"))
+        }
+    }
+
+    fn is_representable<G: CodeGenerator + ?Sized>(
+        generator: &G,
+        ctx: &'ctx Context,
+        llvm_ty: Self::Base,
+    ) -> Result<(), String> {
+        Self::is_representable(llvm_ty, generator.get_size_type(ctx))
+    }
+
     fn new_value<G: CodeGenerator + ?Sized>(
         &self,
         generator: &mut G,
@@ -176,7 +199,7 @@ impl<'ctx> ProxyType<'ctx> for NDArrayType<'ctx> {
     ) -> Self::Value {
         debug_assert_eq!(value.get_type(), self.as_base_type());
 
-        NDArrayValue::from_ptr_val(value, self.llvm_usize, name)
+        NDArrayValue::from_pointer_value(value, self.llvm_usize, name)
     }
 
     fn as_base_type(&self) -> Self::Base {
diff --git a/nac3core/src/codegen/types/range.rs b/nac3core/src/codegen/types/range.rs
index 3b22916..89a1b72 100644
--- a/nac3core/src/codegen/types/range.rs
+++ b/nac3core/src/codegen/types/range.rs
@@ -1,6 +1,6 @@
 use inkwell::{
     context::Context,
-    types::{AnyTypeEnum, IntType, PointerType},
+    types::{AnyTypeEnum, BasicType, BasicTypeEnum, IntType, PointerType},
     values::IntValue,
     AddressSpace,
 };
@@ -19,7 +19,7 @@ pub struct RangeType<'ctx> {
 
 impl<'ctx> RangeType<'ctx> {
     /// Checks whether `llvm_ty` represents a `range` type, returning [Err] if it does not.
-    pub fn is_type(llvm_ty: PointerType<'ctx>) -> Result<(), String> {
+    pub fn is_representable(llvm_ty: PointerType<'ctx>) -> Result<(), String> {
         let llvm_range_ty = llvm_ty.get_element_type();
         let AnyTypeEnum::ArrayType(llvm_range_ty) = llvm_range_ty else {
             return Err(format!("Expected array type for `range` type, got {llvm_range_ty}"));
@@ -59,7 +59,7 @@ impl<'ctx> RangeType<'ctx> {
     /// Creates an [`RangeType`] from a [`PointerType`].
     #[must_use]
     pub fn from_type(ptr_ty: PointerType<'ctx>) -> Self {
-        debug_assert!(Self::is_type(ptr_ty).is_ok());
+        debug_assert!(Self::is_representable(ptr_ty).is_ok());
 
         RangeType { ty: ptr_ty }
     }
@@ -75,6 +75,26 @@ impl<'ctx> ProxyType<'ctx> for RangeType<'ctx> {
     type Base = PointerType<'ctx>;
     type Value = RangeValue<'ctx>;
 
+    fn is_type<G: CodeGenerator + ?Sized>(
+        generator: &G,
+        ctx: &'ctx Context,
+        llvm_ty: impl BasicType<'ctx>,
+    ) -> Result<(), String> {
+        if let BasicTypeEnum::PointerType(ty) = llvm_ty.as_basic_type_enum() {
+            <Self as ProxyType<'ctx>>::is_representable(generator, ctx, ty)
+        } else {
+            Err(format!("Expected pointer type, got {llvm_ty:?}"))
+        }
+    }
+
+    fn is_representable<G: CodeGenerator + ?Sized>(
+        _: &G,
+        _: &'ctx Context,
+        llvm_ty: Self::Base,
+    ) -> Result<(), String> {
+        Self::is_representable(llvm_ty)
+    }
+
     fn new_value<G: CodeGenerator + ?Sized>(
         &self,
         generator: &mut G,
@@ -117,7 +137,7 @@ impl<'ctx> ProxyType<'ctx> for RangeType<'ctx> {
     ) -> Self::Value {
         debug_assert_eq!(value.get_type(), self.as_base_type());
 
-        RangeValue::from_ptr_val(value, name)
+        RangeValue::from_pointer_value(value, name)
     }
 
     fn as_base_type(&self) -> Self::Base {
diff --git a/nac3core/src/codegen/values/list.rs b/nac3core/src/codegen/values/list.rs
index e81993d..7b1975f 100644
--- a/nac3core/src/codegen/values/list.rs
+++ b/nac3core/src/codegen/values/list.rs
@@ -23,18 +23,21 @@ pub struct ListValue<'ctx> {
 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)
+    pub fn is_representable(
+        value: PointerValue<'ctx>,
+        llvm_usize: IntType<'ctx>,
+    ) -> Result<(), String> {
+        ListType::is_representable(value.get_type(), llvm_usize)
     }
 
     /// Creates an [`ListValue`] from a [`PointerValue`].
     #[must_use]
-    pub fn from_ptr_val(
+    pub fn from_pointer_value(
         ptr: PointerValue<'ctx>,
         llvm_usize: IntType<'ctx>,
         name: Option<&'ctx str>,
     ) -> Self {
-        debug_assert!(Self::is_instance(ptr, llvm_usize).is_ok());
+        debug_assert!(Self::is_representable(ptr, llvm_usize).is_ok());
 
         ListValue { value: ptr, llvm_usize, name }
     }
diff --git a/nac3core/src/codegen/values/mod.rs b/nac3core/src/codegen/values/mod.rs
index db1c7bf..29f534e 100644
--- a/nac3core/src/codegen/values/mod.rs
+++ b/nac3core/src/codegen/values/mod.rs
@@ -1,6 +1,7 @@
-use inkwell::values::BasicValue;
+use inkwell::{context::Context, values::BasicValue};
 
 use super::types::ProxyType;
+use crate::codegen::CodeGenerator;
 pub use array::*;
 pub use list::*;
 pub use ndarray::*;
@@ -18,7 +19,25 @@ pub trait ProxyValue<'ctx>: Into<Self::Base> {
     type Base: BasicValue<'ctx>;
 
     /// The type of this value.
-    type Type: ProxyType<'ctx>;
+    type Type: ProxyType<'ctx, Value = Self>;
+
+    /// Checks whether `value` can be represented by this [`ProxyValue`].
+    fn is_instance<G: CodeGenerator + ?Sized>(
+        generator: &G,
+        ctx: &'ctx Context,
+        value: impl BasicValue<'ctx>,
+    ) -> Result<(), String> {
+        Self::Type::is_type(generator, ctx, value.as_basic_value_enum().get_type())
+    }
+
+    /// Checks whether `value` can be represented by this [`ProxyValue`].
+    fn is_representable<G: CodeGenerator + ?Sized>(
+        generator: &G,
+        ctx: &'ctx Context,
+        value: Self::Base,
+    ) -> Result<(), String> {
+        Self::is_instance(generator, ctx, value.as_basic_value_enum())
+    }
 
     /// Returns the [type][ProxyType] of this value.
     fn get_type(&self) -> Self::Type;
diff --git a/nac3core/src/codegen/values/ndarray.rs b/nac3core/src/codegen/values/ndarray.rs
index 23e8836..908ad2f 100644
--- a/nac3core/src/codegen/values/ndarray.rs
+++ b/nac3core/src/codegen/values/ndarray.rs
@@ -27,18 +27,21 @@ pub struct NDArrayValue<'ctx> {
 impl<'ctx> NDArrayValue<'ctx> {
     /// Checks whether `value` is an instance of `NDArray`, returning [Err] if `value` is not an
     /// instance.
-    pub fn is_instance(value: PointerValue<'ctx>, llvm_usize: IntType<'ctx>) -> Result<(), String> {
-        NDArrayType::is_type(value.get_type(), llvm_usize)
+    pub fn is_representable(
+        value: PointerValue<'ctx>,
+        llvm_usize: IntType<'ctx>,
+    ) -> Result<(), String> {
+        NDArrayType::is_representable(value.get_type(), llvm_usize)
     }
 
     /// Creates an [`NDArrayValue`] from a [`PointerValue`].
     #[must_use]
-    pub fn from_ptr_val(
+    pub fn from_pointer_value(
         ptr: PointerValue<'ctx>,
         llvm_usize: IntType<'ctx>,
         name: Option<&'ctx str>,
     ) -> Self {
-        debug_assert!(Self::is_instance(ptr, llvm_usize).is_ok());
+        debug_assert!(Self::is_representable(ptr, llvm_usize).is_ok());
 
         NDArrayValue { value: ptr, llvm_usize, name }
     }
diff --git a/nac3core/src/codegen/values/range.rs b/nac3core/src/codegen/values/range.rs
index 40deb35..7e9976a 100644
--- a/nac3core/src/codegen/values/range.rs
+++ b/nac3core/src/codegen/values/range.rs
@@ -12,14 +12,14 @@ pub struct RangeValue<'ctx> {
 
 impl<'ctx> RangeValue<'ctx> {
     /// Checks whether `value` is an instance of `range`, returning [Err] if `value` is not an instance.
-    pub fn is_instance(value: PointerValue<'ctx>) -> Result<(), String> {
-        RangeType::is_type(value.get_type())
+    pub fn is_representable(value: PointerValue<'ctx>) -> Result<(), String> {
+        RangeType::is_representable(value.get_type())
     }
 
     /// Creates an [`RangeValue`] from a [`PointerValue`].
     #[must_use]
-    pub fn from_ptr_val(ptr: PointerValue<'ctx>, name: Option<&'ctx str>) -> Self {
-        debug_assert!(Self::is_instance(ptr).is_ok());
+    pub fn from_pointer_value(ptr: PointerValue<'ctx>, name: Option<&'ctx str>) -> Self {
+        debug_assert!(Self::is_representable(ptr).is_ok());
 
         RangeValue { value: ptr, name }
     }
diff --git a/nac3core/src/toplevel/builtins.rs b/nac3core/src/toplevel/builtins.rs
index d4f9664..e382222 100644
--- a/nac3core/src/toplevel/builtins.rs
+++ b/nac3core/src/toplevel/builtins.rs
@@ -710,7 +710,7 @@ impl<'a> BuiltinBuilder<'a> {
                         let (zelf_ty, zelf) = obj.unwrap();
                         let zelf =
                             zelf.to_basic_value_enum(ctx, generator, zelf_ty)?.into_pointer_value();
-                        let zelf = RangeValue::from_ptr_val(zelf, Some("range"));
+                        let zelf = RangeValue::from_pointer_value(zelf, Some("range"));
 
                         let mut start = None;
                         let mut stop = None;