diff --git a/flake.nix b/flake.nix
index a6ce5fce..79b1fa63 100644
--- a/flake.nix
+++ b/flake.nix
@@ -163,7 +163,10 @@
           clippy
           pre-commit
           rustfmt
+          rust-analyzer
         ];
+        # https://nixos.wiki/wiki/Rust#Shell.nix_example
+        RUST_SRC_PATH = "${pkgs.rust.packages.stable.rustPlatform.rustLibSrc}";
       };
       devShells.x86_64-linux.msys2 = pkgs.mkShell {
         name = "nac3-dev-shell-msys2";
diff --git a/nac3core/src/codegen/irrt/error_context.rs b/nac3core/src/codegen/irrt/error_context.rs
new file mode 100644
index 00000000..aca77c3e
--- /dev/null
+++ b/nac3core/src/codegen/irrt/error_context.rs
@@ -0,0 +1,81 @@
+use crate::codegen::model::*;
+
+pub struct StrFields<'ctx> {
+    content: Field<PointerModel<FixedIntModel<Byte>>>,
+    length: Field<IntModel<'ctx>>,
+}
+
+#[derive(Debug, Clone)]
+pub struct Str<'ctx> {
+    sizet: IntModel<'ctx>,
+}
+
+impl<'ctx> IsStruct<'ctx> for Str<'ctx> {
+    type Fields = StrFields<'ctx>;
+
+    fn struct_name(&self) -> &'static str {
+        "Str"
+    }
+
+    fn build_fields(&self, builder: &mut FieldBuilder<'ctx>) -> Self::Fields {
+        Self::Fields {
+            content: builder.add_field_auto("content"),
+            length: builder.add_field("length", self.sizet),
+        }
+    }
+}
+
+type ErrorId = Int32;
+pub struct ErrorIdsFields {
+    index_error: Field<FixedIntModel<ErrorId>>,
+    value_error: Field<FixedIntModel<ErrorId>>,
+    assertion_error: Field<FixedIntModel<ErrorId>>,
+    runtime_error: Field<FixedIntModel<ErrorId>>,
+}
+#[derive(Debug, Clone)]
+pub struct ErrorIds;
+
+impl<'ctx> IsStruct<'ctx> for ErrorIds {
+    type Fields = ErrorIdsFields;
+
+    fn struct_name(&self) -> &'static str {
+        "ErrorIds"
+    }
+
+    fn build_fields(&self, builder: &mut FieldBuilder) -> Self::Fields {
+        Self::Fields {
+            index_error: builder.add_field_auto("index_error"),
+            value_error: builder.add_field_auto("value_error"),
+            assertion_error: builder.add_field_auto("assertion_error"),
+            runtime_error: builder.add_field_auto("runtime_error"),
+        }
+    }
+}
+
+pub struct ErrorContextFields {
+    error_id: Field<FixedIntModel<ErrorId>>,
+    message_template: Field<PointerModel<FixedIntModel<Byte>>>,
+    param1: Field<FixedIntModel<Int64>>,
+    param2: Field<FixedIntModel<Int64>>,
+    param3: Field<FixedIntModel<Int64>>,
+}
+#[derive(Debug, Clone)]
+pub struct ErrorContext;
+
+impl<'ctx> IsStruct<'ctx> for ErrorContext {
+    type Fields = ErrorContextFields;
+
+    fn struct_name(&self) -> &'static str {
+        "ErrorIds"
+    }
+
+    fn build_fields(&self, builder: &mut FieldBuilder) -> Self::Fields {
+        Self::Fields {
+            error_id: builder.add_field_auto("error_id"),
+            message_template: builder.add_field_auto("message_template"),
+            param1: builder.add_field_auto("param1"),
+            param2: builder.add_field_auto("param2"),
+            param3: builder.add_field_auto("param3"),
+        }
+    }
+}
diff --git a/nac3core/src/codegen/irrt/util.rs b/nac3core/src/codegen/irrt/util.rs
new file mode 100644
index 00000000..4ca8882c
--- /dev/null
+++ b/nac3core/src/codegen/irrt/util.rs
@@ -0,0 +1,79 @@
+use inkwell::{
+    types::{BasicMetadataTypeEnum, BasicType, IntType},
+    values::{AnyValue, BasicMetadataValueEnum},
+};
+
+use crate::{
+    codegen::{model::*, CodeGenContext},
+    util::SizeVariant,
+};
+
+fn get_size_variant(ty: IntType) -> SizeVariant {
+    match ty.get_bit_width() {
+        32 => SizeVariant::Bits32,
+        64 => SizeVariant::Bits64,
+        _ => unreachable!("Unsupported int type bit width {}", ty.get_bit_width()),
+    }
+}
+
+#[must_use]
+pub fn get_sized_dependent_function_name(ty: IntType, fn_name: &str) -> String {
+    let mut fn_name = fn_name.to_owned();
+    match get_size_variant(ty) {
+        SizeVariant::Bits32 => {
+            // Do nothing, `fn_name` already has the correct name
+        }
+        SizeVariant::Bits64 => {
+            // Append "64", this is the naming convention
+            fn_name.push_str("64");
+        }
+    }
+    fn_name
+}
+
+// TODO: Variadic argument?
+pub struct FunctionBuilder<'ctx, 'a> {
+    ctx: &'a CodeGenContext<'ctx, 'a>,
+    fn_name: &'a str,
+    arguments: Vec<(BasicMetadataTypeEnum<'ctx>, BasicMetadataValueEnum<'ctx>)>,
+}
+
+impl<'ctx, 'a> FunctionBuilder<'ctx, 'a> {
+    pub fn begin(ctx: &'a CodeGenContext<'ctx, 'a>, fn_name: &'a str) -> Self {
+        FunctionBuilder { ctx, fn_name, arguments: Vec::new() }
+    }
+
+    // The name is for self-documentation
+    #[must_use]
+    pub fn arg<M: Model<'ctx>>(mut self, _name: &'static str, model: &M, value: &M::Value) -> Self {
+        self.arguments
+            .push((model.get_llvm_type(self.ctx.ctx).into(), value.get_llvm_value().into()));
+        self
+    }
+
+    pub fn returning<M: Model<'ctx>>(self, name: &'static str, return_model: &M) -> S::MemoryValue {
+        let (param_tys, param_vals): (Vec<_>, Vec<_>) = self.arguments.into_iter().unzip();
+
+        let function = self.ctx.module.get_function(self.fn_name).unwrap_or_else(|| {
+            let return_type = return_model.get_llvm_type(self.ctx.ctx);
+            let fn_type = return_type.fn_type(&param_tys, false);
+            self.ctx.module.add_function(self.fn_name, fn_type, None)
+        });
+
+        let ret = self.ctx.builder.build_call(function, &param_vals, name).unwrap();
+        return_model.check_llvm_value(ret.as_any_value_enum())
+    }
+
+    // TODO: Code duplication, but otherwise returning<S: Optic<'ctx>> cannot resolve S if return_optic = None
+    pub fn returning_void(self) {
+        let (param_tys, param_vals): (Vec<_>, Vec<_>) = self.arguments.into_iter().unzip();
+
+        let function = self.ctx.module.get_function(self.fn_name).unwrap_or_else(|| {
+            let return_type = self.ctx.ctx.void_type();
+            let fn_type = return_type.fn_type(&param_tys, false);
+            self.ctx.module.add_function(self.fn_name, fn_type, None)
+        });
+
+        self.ctx.builder.build_call(function, &param_vals, "").unwrap();
+    }
+}
diff --git a/nac3core/src/codegen/mod.rs b/nac3core/src/codegen/mod.rs
index 17952369..85b963bb 100644
--- a/nac3core/src/codegen/mod.rs
+++ b/nac3core/src/codegen/mod.rs
@@ -41,6 +41,7 @@ pub mod extern_fns;
 mod generator;
 pub mod irrt;
 pub mod llvm_intrinsics;
+pub mod model;
 pub mod numpy;
 pub mod stmt;
 
diff --git a/nac3core/src/codegen/model/core.rs b/nac3core/src/codegen/model/core.rs
new file mode 100644
index 00000000..cfdad12f
--- /dev/null
+++ b/nac3core/src/codegen/model/core.rs
@@ -0,0 +1,37 @@
+/*
+MemoryGetter a
+    { load : Memory -> a
+    }
+
+MemorySetter a
+    { store : Memory -> a -> Memory
+    }
+*/
+
+use inkwell::{
+    context::Context,
+    types::BasicTypeEnum,
+    values::{AnyValueEnum, BasicValueEnum},
+};
+
+use crate::codegen::CodeGenContext;
+
+use super::Pointer;
+
+pub trait ModelValue<'ctx> {
+    fn get_llvm_value(&self) -> BasicValueEnum<'ctx>;
+}
+
+pub trait Model<'ctx>: Clone {
+    type Value: ModelValue<'ctx>;
+
+    fn get_llvm_type(&self, ctx: &'ctx Context) -> BasicTypeEnum<'ctx>;
+    fn check_llvm_value(&self, value: AnyValueEnum<'ctx>) -> Self::Value;
+
+    fn alloca(&self, ctx: &CodeGenContext<'ctx, '_>, name: &str) -> Pointer<'ctx, Self> {
+        Pointer {
+            element: self.clone(),
+            value: ctx.builder.build_alloca(self.get_llvm_type(ctx.ctx), name).unwrap(),
+        }
+    }
+}
diff --git a/nac3core/src/codegen/model/gep.rs b/nac3core/src/codegen/model/gep.rs
new file mode 100644
index 00000000..f54c0f0b
--- /dev/null
+++ b/nac3core/src/codegen/model/gep.rs
@@ -0,0 +1,138 @@
+use inkwell::{
+    context::Context,
+    types::{BasicType, BasicTypeEnum, StructType},
+    values::{AnyValueEnum, BasicValue, BasicValueEnum, StructValue},
+};
+use itertools::Itertools;
+
+use crate::codegen::CodeGenContext;
+
+use super::{Model, ModelValue, Pointer};
+
+#[derive(Debug, Clone)]
+pub struct Field<E> {
+    pub gep_index: u64,
+    pub name: &'static str,
+    pub element: E,
+}
+
+// Like [`Field<E>`] but element must be [`BasicTypeEnum<'ctx>`]
+#[derive(Debug)]
+struct FieldLLVM<'ctx> {
+    gep_index: u64,
+    name: &'ctx str,
+    llvm_type: BasicTypeEnum<'ctx>,
+}
+
+#[derive(Debug)]
+pub struct FieldBuilder<'ctx> {
+    pub ctx: &'ctx Context,
+    gep_index_counter: u64,
+    struct_name: &'ctx str,
+    fields: Vec<FieldLLVM<'ctx>>,
+}
+
+impl<'ctx> FieldBuilder<'ctx> {
+    #[must_use]
+    pub fn new(ctx: &'ctx Context, struct_name: &'ctx str) -> Self {
+        FieldBuilder { ctx, gep_index_counter: 0, struct_name, fields: Vec::new() }
+    }
+
+    fn next_gep_index(&mut self) -> u64 {
+        let index = self.gep_index_counter;
+        self.gep_index_counter += 1;
+        index
+    }
+
+    pub fn add_field<E: Model<'ctx>>(&mut self, name: &'static str, element: E) -> Field<E> {
+        let gep_index = self.next_gep_index();
+
+        self.fields.push(FieldLLVM { gep_index, name, llvm_type: element.get_llvm_type(self.ctx) });
+
+        Field { gep_index, name, element }
+    }
+
+    pub fn add_field_auto<E: Model<'ctx> + Default>(&mut self, name: &'static str) -> Field<E> {
+        self.add_field(name, E::default())
+    }
+}
+
+pub trait IsStruct<'ctx>: Clone {
+    type Fields;
+
+    fn struct_name(&self) -> &'static str;
+
+    fn build_fields(&self, builder: &mut FieldBuilder<'ctx>) -> Self::Fields;
+
+    fn get_fields(&self, ctx: &'ctx Context) -> Self::Fields {
+        let mut builder = FieldBuilder::new(ctx, self.struct_name());
+        self.build_fields(&mut builder)
+    }
+
+    fn get_struct_type(&self, ctx: &'ctx Context) -> StructType<'ctx> {
+        let mut builder = FieldBuilder::new(ctx, self.struct_name());
+        self.build_fields(&mut builder); // Self::Fields is discarded
+
+        let field_types =
+            builder.fields.iter().map(|field_info| field_info.llvm_type).collect_vec();
+        ctx.struct_type(&field_types, false)
+    }
+}
+
+// To play nice with Rust's trait resolution
+#[derive(Debug, Clone)]
+pub struct StructModel<S>(pub S);
+
+// TODO: enrich it
+pub struct Struct<'ctx, S> {
+    pub structure: S,
+    pub value: StructValue<'ctx>,
+}
+
+impl<'ctx, S: IsStruct<'ctx>> ModelValue<'ctx> for Struct<'ctx, S> {
+    fn get_llvm_value(&self) -> BasicValueEnum<'ctx> {
+        self.value.as_basic_value_enum()
+    }
+}
+
+impl<'ctx, S: IsStruct<'ctx>> Model<'ctx> for StructModel<S> {
+    type Value = Struct<'ctx, S>; // TODO: enrich it
+
+    fn get_llvm_type(&self, ctx: &'ctx Context) -> BasicTypeEnum<'ctx> {
+        self.0.get_struct_type(ctx).as_basic_type_enum()
+    }
+
+    fn check_llvm_value(&self, value: AnyValueEnum<'ctx>) -> Self::Value {
+        // TODO: check structure
+        Struct { structure: self.0.clone(), value: value.into_struct_value() }
+    }
+}
+
+impl<'ctx, S: IsStruct<'ctx>> Pointer<'ctx, StructModel<S>> {
+    pub fn gep<E, GetFieldFn>(
+        &self,
+        ctx: &CodeGenContext<'ctx, '_>,
+        get_field: GetFieldFn,
+    ) -> Pointer<'ctx, E>
+    where
+        E: Model<'ctx>,
+        GetFieldFn: FnOnce(S::Fields) -> Field<E>,
+    {
+        let fields = self.element.0.get_fields(ctx.ctx);
+        let field = get_field(fields);
+
+        let llvm_i32 = ctx.ctx.i32_type(); // TODO: I think I'm not supposed to *just* use i32 for GEP like that
+
+        let ptr = unsafe {
+            ctx.builder
+                .build_in_bounds_gep(
+                    self.value,
+                    &[llvm_i32.const_zero(), llvm_i32.const_int(field.gep_index, false)],
+                    field.name,
+                )
+                .unwrap()
+        };
+
+        Pointer { element: field.element, value: ptr }
+    }
+}
diff --git a/nac3core/src/codegen/model/int.rs b/nac3core/src/codegen/model/int.rs
new file mode 100644
index 00000000..ebf06408
--- /dev/null
+++ b/nac3core/src/codegen/model/int.rs
@@ -0,0 +1,121 @@
+use inkwell::{
+    context::Context,
+    types::{BasicType, BasicTypeEnum, IntType},
+    values::{AnyValueEnum, BasicValue, BasicValueEnum, IntValue},
+};
+
+use super::core::*;
+
+#[derive(Debug, Clone, Copy)]
+pub struct IntModel<'ctx>(pub IntType<'ctx>);
+pub struct Int<'ctx>(pub IntValue<'ctx>);
+
+impl<'ctx> ModelValue<'ctx> for Int<'ctx> {
+    fn get_llvm_value(&self) -> BasicValueEnum<'ctx> {
+        self.0.as_basic_value_enum()
+    }
+}
+
+impl<'ctx> Model<'ctx> for IntModel<'ctx> {
+    type Value = Int<'ctx>;
+
+    fn get_llvm_type(&self, _ctx: &'ctx Context) -> BasicTypeEnum<'ctx> {
+        self.0.as_basic_type_enum()
+    }
+
+    fn check_llvm_value(&self, value: AnyValueEnum<'ctx>) -> Self::Value {
+        let int = value.into_int_value();
+        assert_eq!(int.get_type().get_bit_width(), self.0.get_bit_width());
+        Int(int)
+    }
+}
+
+#[derive(Debug, Clone, Default)]
+pub struct FixedIntModel<T>(pub T);
+pub struct FixedInt<'ctx, T: IsFixedInt> {
+    pub int: T,
+    pub value: IntValue<'ctx>,
+}
+
+pub trait IsFixedInt: Clone + Default {
+    fn get_int_type(ctx: &Context) -> IntType<'_>;
+    fn get_bit_width() -> u32; // This is required, instead of only relying on get_int_type
+}
+
+impl<'ctx, T: IsFixedInt> ModelValue<'ctx> for FixedInt<'ctx, T> {
+    fn get_llvm_value(&self) -> BasicValueEnum<'ctx> {
+        self.value.as_basic_value_enum()
+    }
+}
+
+impl<'ctx, T: IsFixedInt> Model<'ctx> for FixedIntModel<T> {
+    type Value = FixedInt<'ctx, T>;
+
+    fn get_llvm_type(&self, ctx: &'ctx Context) -> BasicTypeEnum<'ctx> {
+        T::get_int_type(ctx).as_basic_type_enum()
+    }
+
+    fn check_llvm_value(&self, value: AnyValueEnum<'ctx>) -> Self::Value {
+        let value = value.into_int_value();
+        assert_eq!(value.get_type().get_bit_width(), T::get_bit_width());
+        FixedInt { int: self.0.clone(), value }
+    }
+}
+
+impl<'ctx, T: IsFixedInt> FixedIntModel<T> {
+    pub fn constant(&self, ctx: &'ctx Context, value: u64) -> FixedInt<'ctx, T> {
+        FixedInt { int: self.0.clone(), value: T::get_int_type(ctx).const_int(value, false) }
+    }
+}
+
+#[derive(Debug, Clone, Default)]
+pub struct Bool;
+
+impl IsFixedInt for Bool {
+    fn get_int_type(ctx: &Context) -> IntType<'_> {
+        ctx.bool_type()
+    }
+
+    fn get_bit_width() -> u32 {
+        1
+    }
+}
+
+#[derive(Debug, Clone, Default)]
+pub struct Byte;
+
+impl IsFixedInt for Byte {
+    fn get_int_type(ctx: &Context) -> IntType<'_> {
+        ctx.i8_type()
+    }
+
+    fn get_bit_width() -> u32 {
+        8
+    }
+}
+
+#[derive(Debug, Clone, Default)]
+pub struct Int32;
+
+impl IsFixedInt for Int32 {
+    fn get_int_type(ctx: &Context) -> IntType<'_> {
+        ctx.i32_type()
+    }
+
+    fn get_bit_width() -> u32 {
+        32
+    }
+}
+
+#[derive(Debug, Clone, Default)]
+pub struct Int64;
+
+impl IsFixedInt for Int64 {
+    fn get_int_type(ctx: &Context) -> IntType<'_> {
+        ctx.i64_type()
+    }
+
+    fn get_bit_width() -> u32 {
+        64
+    }
+}
diff --git a/nac3core/src/codegen/model/mod.rs b/nac3core/src/codegen/model/mod.rs
new file mode 100644
index 00000000..2ce82e0e
--- /dev/null
+++ b/nac3core/src/codegen/model/mod.rs
@@ -0,0 +1,11 @@
+pub mod core;
+pub mod gep;
+pub mod int;
+pub mod pointer;
+pub mod slice;
+
+pub use core::*;
+pub use gep::*;
+pub use int::*;
+pub use pointer::*;
+pub use slice::*;
diff --git a/nac3core/src/codegen/model/pointer.rs b/nac3core/src/codegen/model/pointer.rs
new file mode 100644
index 00000000..45c6ac6f
--- /dev/null
+++ b/nac3core/src/codegen/model/pointer.rs
@@ -0,0 +1,74 @@
+use inkwell::{
+    context::Context,
+    types::{BasicType, BasicTypeEnum},
+    values::{AnyValue, AnyValueEnum, BasicValue, BasicValueEnum, PointerValue},
+    AddressSpace,
+};
+
+use crate::codegen::CodeGenContext;
+
+use super::core::*;
+
+pub struct Pointer<'ctx, E: Model<'ctx>> {
+    pub element: E,
+    pub value: PointerValue<'ctx>,
+}
+
+#[derive(Debug, Clone, Default)]
+pub struct PointerModel<E>(pub E);
+
+impl<'ctx, E: Model<'ctx>> ModelValue<'ctx> for Pointer<'ctx, E> {
+    fn get_llvm_value(&self) -> BasicValueEnum<'ctx> {
+        self.value.as_basic_value_enum()
+    }
+}
+
+impl<'ctx, E: Model<'ctx>> Pointer<'ctx, E> {
+    pub fn store(&self, ctx: &CodeGenContext<'ctx, '_>, val: &E::Value) {
+        ctx.builder.build_store(self.value, val.get_llvm_value()).unwrap();
+    }
+
+    pub fn load(&self, ctx: &CodeGenContext<'ctx, '_>, name: &str) -> E::Value {
+        let val = ctx.builder.build_load(self.value, name).unwrap();
+        self.element.check_llvm_value(val.as_any_value_enum())
+    }
+}
+
+impl<'ctx, E: Model<'ctx>> Model<'ctx> for PointerModel<E> {
+    type Value = Pointer<'ctx, E>;
+
+    fn get_llvm_type(&self, ctx: &'ctx Context) -> BasicTypeEnum<'ctx> {
+        self.0.get_llvm_type(ctx).ptr_type(AddressSpace::default()).as_basic_type_enum()
+    }
+
+    fn check_llvm_value(&self, value: AnyValueEnum<'ctx>) -> Self::Value {
+        // TODO: Check get_element_type()? for LLVM 14 at least...
+        Pointer { element: self.0.clone(), value: value.into_pointer_value() }
+    }
+}
+
+pub struct OpaquePointer<'ctx>(pub PointerValue<'ctx>);
+
+#[derive(Debug, Clone, Default)]
+pub struct OpaquePointerModel;
+
+impl<'ctx> ModelValue<'ctx> for OpaquePointer<'ctx> {
+    fn get_llvm_value(&self) -> BasicValueEnum<'ctx> {
+        self.0.as_basic_value_enum()
+    }
+}
+
+impl<'ctx> Model<'ctx> for OpaquePointerModel {
+    type Value = OpaquePointer<'ctx>;
+
+    fn get_llvm_type(&self, ctx: &'ctx Context) -> BasicTypeEnum<'ctx> {
+        ctx.i8_type().ptr_type(AddressSpace::default()).as_basic_type_enum()
+    }
+
+    fn check_llvm_value(&self, value: AnyValueEnum<'ctx>) -> Self::Value {
+        let ptr = value.into_pointer_value();
+        // TODO: remove this check once LLVM pointers do not have `get_element_type()`
+        assert_eq!(ptr.get_type().get_element_type().into_int_type().get_bit_width(), 8);
+        OpaquePointer(ptr)
+    }
+}
diff --git a/nac3core/src/codegen/model/slice.rs b/nac3core/src/codegen/model/slice.rs
new file mode 100644
index 00000000..8e3cefa0
--- /dev/null
+++ b/nac3core/src/codegen/model/slice.rs
@@ -0,0 +1,75 @@
+use inkwell::values::IntValue;
+
+use crate::codegen::{CodeGenContext, CodeGenerator};
+
+use super::{Int, Model, Pointer};
+
+pub struct ArraySlice<'ctx, E: Model<'ctx>> {
+    pub num_elements: Int<'ctx>,
+    pub pointer: Pointer<'ctx, E>,
+}
+
+impl<'ctx, E: Model<'ctx>> ArraySlice<'ctx, E> {
+    pub fn ix_unchecked(
+        &self,
+        ctx: &CodeGenContext<'ctx, '_>,
+        idx: IntValue<'ctx>,
+        name: &str,
+    ) -> Pointer<'ctx, E> {
+        let element_addr =
+            unsafe { ctx.builder.build_in_bounds_gep(self.pointer.value, &[idx], name).unwrap() };
+        Pointer { value: element_addr, element: self.pointer.element.clone() }
+    }
+
+    pub fn ix<G: CodeGenerator + ?Sized>(
+        &self,
+        generator: &mut G,
+        ctx: &mut CodeGenContext<'ctx, '_>,
+        idx: IntValue<'ctx>,
+        name: &str,
+    ) -> Pointer<'ctx, E> {
+        let int_type = self.num_elements.0.get_type(); // NOTE: Weird get_type(), see comment under `trait Ixed`
+
+        assert_eq!(int_type.get_bit_width(), idx.get_type().get_bit_width()); // Might as well check bit width to catch bugs
+
+        // TODO: SGE or UGE? or make it defined by the implementee?
+
+        // Check `0 <= index`
+        let lower_bounded = ctx
+            .builder
+            .build_int_compare(
+                inkwell::IntPredicate::SLE,
+                int_type.const_zero(),
+                idx,
+                "lower_bounded",
+            )
+            .unwrap();
+
+        // Check `index < num_elements`
+        let upper_bounded = ctx
+            .builder
+            .build_int_compare(
+                inkwell::IntPredicate::SLT,
+                idx,
+                self.num_elements.0,
+                "upper_bounded",
+            )
+            .unwrap();
+
+        // Compute `0 <= index && index < num_elements`
+        let bounded = ctx.builder.build_and(lower_bounded, upper_bounded, "bounded").unwrap();
+
+        // Assert `bounded`
+        ctx.make_assert(
+            generator,
+            bounded,
+            "0:IndexError",
+            "nac3core LLVM codegen attempting to access out of bounds array index {0}. Must satisfy 0 <= index < {2}",
+            [ Some(idx), Some(self.num_elements.0), None],
+            ctx.current_loc
+        );
+
+        // ...and finally do indexing
+        self.ix_unchecked(ctx, idx, name)
+    }
+}