diff --git a/nac3core/src/codegen/irrt/classes.rs b/nac3core/src/codegen/irrt/classes.rs
new file mode 100644
index 00000000..195f04b7
--- /dev/null
+++ b/nac3core/src/codegen/irrt/classes.rs
@@ -0,0 +1,94 @@
+use inkwell::types::{BasicTypeEnum, IntType};
+
+use crate::codegen::optics::{AddressLens, GepGetter, IntLens, StructureOptic};
+
+// use crate::codegen::structure::{
+//     FieldLensBuilder, IntLens, LensWithFieldInfo, PointerLens, StructFieldLens,
+// };
+
+pub struct NpArrayFields<'ctx> {
+    pub data: GepGetter<AddressLens<IntLens<'ctx>>>,
+    pub itemsize: GepGetter<IntLens<'ctx>>,
+    pub ndims: GepGetter<IntLens<'ctx>>,
+    pub shape: GepGetter<AddressLens<IntLens<'ctx>>>,
+    pub strides: GepGetter<AddressLens<IntLens<'ctx>>>,
+}
+
+#[derive(Debug, Clone, Copy)]
+pub struct NpArrayLens<'ctx> {
+    pub size_type: IntType<'ctx>,
+    pub elem_type: BasicTypeEnum<'ctx>,
+}
+
+impl<'ctx> StructureOptic<'ctx> for NpArrayLens<'ctx> {
+    type Fields = NpArrayFields<'ctx>;
+
+    fn struct_name(&self) -> &'static str {
+        "NDArray"
+    }
+
+    fn build_fields(
+        &self,
+        builder: &mut crate::codegen::optics::FieldBuilder<'ctx>,
+    ) -> Self::Fields {
+        NpArrayFields {
+            data: builder.add_field("data", AddressLens(IntLens(builder.ctx.i8_type()))),
+            itemsize: builder.add_field("itemsize", IntLens(builder.ctx.i8_type())),
+            ndims: builder.add_field("ndims", IntLens(builder.ctx.i8_type())),
+            shape: builder.add_field("shape", AddressLens(IntLens(self.size_type))),
+            strides: builder.add_field("strides", AddressLens(IntLens(self.size_type))),
+        }
+    }
+}
+
+pub struct IrrtStringFields<'ctx> {
+    pub buffer: GepGetter<AddressLens<IntLens<'ctx>>>,
+    pub capacity: GepGetter<IntLens<'ctx>>,
+    pub cursor: GepGetter<IntLens<'ctx>>,
+}
+
+#[derive(Debug, Clone, Copy)]
+pub struct IrrtStringLens;
+
+impl<'ctx> StructureOptic<'ctx> for IrrtStringLens {
+    type Fields = IrrtStringFields<'ctx>;
+
+    fn struct_name(&self) -> &'static str {
+        todo!()
+    }
+
+    fn build_fields(
+        &self,
+        builder: &mut crate::codegen::optics::FieldBuilder<'ctx>,
+    ) -> Self::Fields {
+        let llvm_i8 = builder.ctx.i8_type();
+        let llvm_i32 = builder.ctx.i32_type();
+        IrrtStringFields {
+            buffer: builder.add_field("buffer", AddressLens(IntLens(llvm_i8))),
+            capacity: builder.add_field("capacity", IntLens(llvm_i32)),
+            cursor: builder.add_field("cursor", IntLens(llvm_i32)),
+        }
+    }
+}
+
+pub struct ErrorContextFields {
+    pub message: GepGetter<IrrtStringLens>,
+}
+
+#[derive(Debug, Clone, Copy)]
+pub struct ErrorContextLens;
+
+impl<'ctx> StructureOptic<'ctx> for ErrorContextLens {
+    type Fields = ErrorContextFields;
+
+    fn struct_name(&self) -> &'static str {
+        "ErrorContext"
+    }
+
+    fn build_fields(
+        &self,
+        builder: &mut crate::codegen::optics::FieldBuilder<'ctx>,
+    ) -> Self::Fields {
+        ErrorContextFields { message: builder.add_field("message", IrrtStringLens) }
+    }
+}
diff --git a/nac3core/src/codegen/mod.rs b/nac3core/src/codegen/mod.rs
index 17952369..11c4d4ef 100644
--- a/nac3core/src/codegen/mod.rs
+++ b/nac3core/src/codegen/mod.rs
@@ -42,6 +42,7 @@ mod generator;
 pub mod irrt;
 pub mod llvm_intrinsics;
 pub mod numpy;
+pub mod optics;
 pub mod stmt;
 
 #[cfg(test)]
diff --git a/nac3core/src/codegen/optics.rs b/nac3core/src/codegen/optics.rs
new file mode 100644
index 00000000..0465ba9d
--- /dev/null
+++ b/nac3core/src/codegen/optics.rs
@@ -0,0 +1,342 @@
+use inkwell::{
+    context::Context,
+    types::{BasicType, BasicTypeEnum, IntType},
+    values::{AnyValue, BasicValue, BasicValueEnum, IntValue, PointerValue, StructValue},
+    AddressSpace,
+};
+use itertools::Itertools;
+
+use super::CodeGenContext;
+
+// TODO: Write a taxonomy
+
+pub trait OpticValue<'ctx> {
+    fn get_llvm_value(&self) -> BasicValueEnum<'ctx>;
+}
+
+impl<'ctx, T: BasicValue<'ctx>> OpticValue<'ctx> for T {
+    fn get_llvm_value(&self) -> BasicValueEnum<'ctx> {
+        self.as_basic_value_enum()
+    }
+}
+
+// TODO: The interface is unintuitive
+pub trait Optic<'ctx>: Clone {
+    type Value: OpticValue<'ctx>;
+
+    fn get_llvm_type(&self, ctx: &'ctx Context) -> BasicTypeEnum<'ctx>;
+
+    fn alloca(&self, ctx: &CodeGenContext<'ctx, '_>, name: &str) -> Address<'ctx, Self> {
+        let ptr = ctx.builder.build_alloca(self.get_llvm_type(ctx.ctx), name).unwrap();
+        Address { addressee_optic: self.clone(), address: ptr }
+    }
+}
+
+pub trait Prism<'ctx>: Optic<'ctx> {
+    // TODO: Return error if `review` fails
+    fn review<V: AnyValue<'ctx>>(&self, value: V) -> Self::Value;
+}
+
+pub trait MemoryGetter<'ctx>: Optic<'ctx> {
+    fn get(
+        &self,
+        ctx: &CodeGenContext<'ctx, '_>,
+        pointer: PointerValue<'ctx>,
+        name: &str,
+    ) -> Self::Value;
+}
+
+pub trait MemorySetter<'ctx>: Optic<'ctx> {
+    fn set(&self, ctx: &CodeGenContext<'ctx, '_>, pointer: PointerValue<'ctx>, value: &Self::Value);
+}
+
+pub trait SizedIntLens<'ctx>: Optic<'ctx, Value = IntValue<'ctx>> {}
+
+// NOTE: I wanted to make Int8Lens, Int16Lens, Int32Lens, with all
+// having the trait IsIntLens, and implement `impl <S: IsIntLens> Optic<S> for T`,
+// but that clashes with StructureOptic!!
+#[derive(Debug, Clone, Copy)]
+pub struct IntLens<'ctx>(pub IntType<'ctx>);
+
+impl<'ctx> Optic<'ctx> for IntLens<'ctx> {
+    type Value = IntValue<'ctx>;
+
+    fn get_llvm_type(&self, _ctx: &'ctx Context) -> BasicTypeEnum<'ctx> {
+        self.0.as_basic_type_enum()
+    }
+}
+
+impl<'ctx> Prism<'ctx> for IntLens<'ctx> {
+    fn review<V: AnyValue<'ctx>>(&self, value: V) -> Self::Value {
+        let int = value.as_any_value_enum().into_int_value();
+        debug_assert_eq!(int.get_type().get_bit_width(), self.0.get_bit_width());
+        int
+    }
+}
+
+impl<'ctx> MemoryGetter<'ctx> for IntLens<'ctx> {
+    fn get(
+        &self,
+        ctx: &CodeGenContext<'ctx, '_>,
+        pointer: PointerValue<'ctx>,
+        name: &str,
+    ) -> Self::Value {
+        self.review(ctx.builder.build_load(pointer, name).unwrap())
+    }
+}
+
+impl<'ctx> MemorySetter<'ctx> for IntLens<'ctx> {
+    fn set(&self, ctx: &CodeGenContext<'ctx, '_>, pointer: PointerValue<'ctx>, int: &Self::Value) {
+        debug_assert_eq!(int.get_type().get_bit_width(), self.0.get_bit_width());
+        ctx.builder.build_store(pointer, int.as_basic_value_enum()).unwrap();
+    }
+}
+
+#[derive(Debug, Clone)]
+pub struct Address<'ctx, AddresseeOptic> {
+    pub addressee_optic: AddresseeOptic,
+    pub address: PointerValue<'ctx>,
+}
+
+impl<'ctx, AddresseeOptic> Address<'ctx, AddresseeOptic> {
+    pub fn cast_to<S: Optic<'ctx>>(
+        &self,
+        ctx: &CodeGenContext<'ctx, '_>,
+        new_optic: S,
+    ) -> Address<'ctx, S> {
+        let to_ptr_type = new_optic.get_llvm_type(ctx.ctx).ptr_type(AddressSpace::default());
+        let casted_address =
+            ctx.builder.build_pointer_cast(self.address, to_ptr_type, "ptr_casted").unwrap();
+        Address { addressee_optic: new_optic, address: casted_address }
+    }
+
+    pub fn cast_to_opaque(&self, ctx: &CodeGenContext<'ctx, '_>) -> Address<'ctx, IntLens<'ctx>> {
+        self.cast_to(ctx, IntLens(ctx.ctx.i8_type()))
+    }
+}
+
+impl<'ctx, AddresseeOptic> OpticValue<'ctx> for Address<'ctx, AddresseeOptic> {
+    fn get_llvm_value(&self) -> BasicValueEnum<'ctx> {
+        self.address.as_basic_value_enum()
+    }
+}
+
+#[derive(Debug, Clone)]
+pub struct AddressLens<AddresseeOptic>(pub AddresseeOptic);
+
+impl<'ctx, AddresseeOptic: Optic<'ctx>> Optic<'ctx> for AddressLens<AddresseeOptic> {
+    type Value = Address<'ctx, AddresseeOptic>;
+
+    fn get_llvm_type(&self, ctx: &'ctx Context) -> BasicTypeEnum<'ctx> {
+        self.0.get_llvm_type(ctx).ptr_type(AddressSpace::default()).as_basic_type_enum()
+    }
+}
+
+impl<'ctx, AddresseeOptic: Optic<'ctx>> Prism<'ctx> for AddressLens<AddresseeOptic> {
+    fn review<V: AnyValue<'ctx>>(&self, value: V) -> Self::Value {
+        Address {
+            addressee_optic: self.0.clone(),
+            address: value.as_any_value_enum().into_pointer_value(),
+        }
+    }
+}
+
+impl<'ctx, AddressesOptic: Optic<'ctx>> MemoryGetter<'ctx> for AddressLens<AddressesOptic> {
+    fn get(
+        &self,
+        ctx: &CodeGenContext<'ctx, '_>,
+        pointer: PointerValue<'ctx>,
+        name: &str,
+    ) -> Self::Value {
+        self.review(ctx.builder.build_load(pointer, name).unwrap())
+    }
+}
+
+impl<'ctx, AddressesOptic: Optic<'ctx>> MemorySetter<'ctx> for AddressLens<AddressesOptic> {
+    fn set(
+        &self,
+        ctx: &CodeGenContext<'ctx, '_>,
+        pointer: PointerValue<'ctx>,
+        value: &Self::Value,
+    ) {
+        ctx.builder.build_store(pointer, value.address).unwrap();
+    }
+}
+
+// To make [`Address`] convenient to use
+impl<'ctx, AddresseeOptic: MemoryGetter<'ctx>> Address<'ctx, AddresseeOptic> {
+    pub fn load(&self, ctx: &CodeGenContext<'ctx, '_>, name: &str) -> AddresseeOptic::Value {
+        self.addressee_optic.get(ctx, self.address, name)
+    }
+}
+
+// To make [`Address`] convenient to use
+impl<'ctx, AddresseeOptic: MemorySetter<'ctx>> Address<'ctx, AddresseeOptic> {
+    pub fn set(&self, ctx: &CodeGenContext<'ctx, '_>, value: &AddresseeOptic::Value) {
+        self.addressee_optic.set(ctx, self.address, value)
+    }
+}
+
+// ((Memory, Pointer) -> ElementOptic::Value*)
+#[derive(Debug, Clone)]
+pub struct GepGetter<ElementOptic> {
+    /// The LLVM GEP index
+    pub gep_index: u32, // TODO: I think I'm not supposed to *just* use i32 for GEP like that
+    /// Element (or field in the context of `struct`s) name. Used for cosmetics.
+    pub name: &'static str,
+    /// The lens to view the actual value after applying this [`FieldLens<T>`]
+    pub element_optic: ElementOptic,
+}
+
+impl<'ctx, ElementOptic: Optic<'ctx>> Optic<'ctx> for GepGetter<ElementOptic> {
+    type Value = Address<'ctx, ElementOptic>;
+
+    fn get_llvm_type(&self, ctx: &'ctx Context) -> BasicTypeEnum<'ctx> {
+        self.element_optic.get_llvm_type(ctx).ptr_type(AddressSpace::default()).as_basic_type_enum()
+    }
+}
+
+impl<'ctx, ElementOptic: Optic<'ctx>> MemoryGetter<'ctx> for GepGetter<ElementOptic> {
+    fn get(
+        &self,
+        ctx: &CodeGenContext<'ctx, '_>,
+        pointer: PointerValue<'ctx>,
+        name: &str,
+    ) -> Self::Value {
+        let llvm_i32 = ctx.ctx.i32_type(); // TODO: I think I'm not supposed to *just* use i32 for GEP like that
+        let element_ptr = unsafe {
+            ctx.builder
+                .build_in_bounds_gep(
+                    pointer,
+                    &[llvm_i32.const_zero(), llvm_i32.const_int(self.gep_index as u64, false)],
+                    name,
+                )
+                .unwrap()
+        };
+        Address { address: element_ptr, addressee_optic: self.element_optic.clone() }
+    }
+}
+
+// Only used by [`FieldBuilder`]
+#[derive(Debug)]
+struct FieldInfo<'ctx> {
+    gep_index: u32,
+    name: &'ctx str,
+    llvm_type: BasicTypeEnum<'ctx>,
+}
+
+#[derive(Debug)]
+pub struct FieldBuilder<'ctx> {
+    pub ctx: &'ctx Context,
+    gep_index_counter: u32,
+    struct_name: &'ctx str,
+    fields: Vec<FieldInfo<'ctx>>,
+}
+
+impl<'ctx> FieldBuilder<'ctx> {
+    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) -> u32 {
+        let index = self.gep_index_counter;
+        self.gep_index_counter += 1;
+        index
+    }
+
+    pub fn add_field<ElementOptic: Optic<'ctx>>(
+        &mut self,
+        name: &'static str,
+        element_optic: ElementOptic,
+    ) -> GepGetter<ElementOptic> {
+        let gep_index = self.next_gep_index();
+
+        self.fields.push(FieldInfo {
+            gep_index,
+            name,
+            llvm_type: element_optic.get_llvm_type(self.ctx),
+        });
+
+        GepGetter { gep_index, name, element_optic }
+    }
+}
+
+pub trait StructureOptic<'ctx>: Clone {
+    // Fields of optics
+    type Fields;
+
+    // TODO: Make it an associated function instead?
+    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)
+    }
+}
+
+pub struct OpticalStructValue<'ctx, StructOptic> {
+    optic: StructOptic,
+    llvm: StructValue<'ctx>,
+}
+
+impl<'ctx, StructOptic> OpticValue<'ctx> for OpticalStructValue<'ctx, StructOptic> {
+    fn get_llvm_value(&self) -> BasicValueEnum<'ctx> {
+        self.llvm.as_basic_value_enum()
+    }
+}
+
+// TODO: check StructType
+impl<'ctx, T: StructureOptic<'ctx>> Optic<'ctx> for T {
+    type Value = OpticalStructValue<'ctx, Self>;
+
+    fn get_llvm_type(&self, ctx: &'ctx Context) -> BasicTypeEnum<'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).as_basic_type_enum()
+    }
+}
+
+impl<'ctx, T: StructureOptic<'ctx>> MemoryGetter<'ctx> for T {
+    fn get(
+        &self,
+        ctx: &CodeGenContext<'ctx, '_>,
+        pointer: PointerValue<'ctx>,
+        name: &str,
+    ) -> Self::Value {
+        OpticalStructValue {
+            optic: self.clone(),
+            llvm: ctx.builder.build_load(pointer, name).unwrap().into_struct_value(),
+        }
+    }
+}
+
+impl<'ctx, T: StructureOptic<'ctx>> MemorySetter<'ctx> for T {
+    fn set(
+        &self,
+        ctx: &CodeGenContext<'ctx, '_>,
+        pointer: PointerValue<'ctx>,
+        value: &Self::Value,
+    ) {
+        ctx.builder.build_store(pointer, value.llvm).unwrap();
+    }
+}
+
+impl<'ctx, AddresseeOptic: StructureOptic<'ctx>> Address<'ctx, AddresseeOptic> {
+    pub fn view<GetFieldGepFn, FieldElementOptic: Optic<'ctx>>(
+        &self,
+        ctx: &CodeGenContext<'ctx, '_>,
+        get_field_gep_fn: GetFieldGepFn,
+    ) -> Address<'ctx, FieldElementOptic>
+    where
+        GetFieldGepFn: FnOnce(&AddresseeOptic::Fields) -> &GepGetter<FieldElementOptic>,
+    {
+        let fields = self.addressee_optic.get_fields(ctx.ctx);
+        let field = get_field_gep_fn(&fields);
+        field.get(ctx, self.address, field.name)
+    }
+}