diff --git a/crates/aiken-lang/src/builtins.rs b/crates/aiken-lang/src/builtins.rs
index 0975965c..3d9858cf 100644
--- a/crates/aiken-lang/src/builtins.rs
+++ b/crates/aiken-lang/src/builtins.rs
@@ -1,4 +1,5 @@
 use crate::{
+    aiken_fn,
     ast::{
         Annotation, ArgName, CallArg, DataTypeKey, Function, FunctionAccessKey, ModuleKind,
         OnTestFailure, Span, TypedArg, TypedDataType, TypedFunction, UnOp,
@@ -268,6 +269,102 @@ pub fn prelude(id_gen: &IdGenerator) -> TypeInfo {
         ),
     );
 
+    // enumerate
+    let enumerate_a = generic_var(id_gen.next());
+    let enumerate_b = generic_var(id_gen.next());
+    prelude.values.insert(
+        "enumerate".to_string(),
+        ValueConstructor::public(
+            function(
+                vec![
+                    list(enumerate_a.clone()),
+                    enumerate_b.clone(),
+                    function(
+                        vec![enumerate_a.clone(), enumerate_b.clone()],
+                        enumerate_b.clone(),
+                    ),
+                    function(
+                        vec![enumerate_a.clone(), enumerate_b.clone()],
+                        enumerate_b.clone(),
+                    ),
+                ],
+                enumerate_b,
+            ),
+            ValueConstructorVariant::ModuleFn {
+                name: "enumerate".to_string(),
+                field_map: None,
+                module: "".to_string(),
+                arity: 4,
+                location: Span::empty(),
+                builtin: None,
+            },
+        ),
+    );
+
+    // encode_base16
+    prelude.values.insert(
+        "encode_base16".to_string(),
+        ValueConstructor::public(
+            function(vec![byte_array(), int(), byte_array()], byte_array()),
+            ValueConstructorVariant::ModuleFn {
+                name: "encode_base16".to_string(),
+                field_map: None,
+                module: "".to_string(),
+                arity: 3,
+                location: Span::empty(),
+                builtin: None,
+            },
+        ),
+    );
+
+    // from_int
+    prelude.values.insert(
+        "from_int".to_string(),
+        ValueConstructor::public(
+            function(vec![int(), byte_array()], byte_array()),
+            ValueConstructorVariant::ModuleFn {
+                name: "from_int".to_string(),
+                field_map: None,
+                module: "".to_string(),
+                arity: 2,
+                location: Span::empty(),
+                builtin: None,
+            },
+        ),
+    );
+
+    // do_from_int
+    prelude.values.insert(
+        "do_from_int".to_string(),
+        ValueConstructor::public(
+            function(vec![int(), byte_array()], byte_array()),
+            ValueConstructorVariant::ModuleFn {
+                name: "do_from_int".to_string(),
+                field_map: None,
+                module: "".to_string(),
+                arity: 2,
+                location: Span::empty(),
+                builtin: None,
+            },
+        ),
+    );
+
+    // diagnostic
+    prelude.values.insert(
+        "diagnostic".to_string(),
+        ValueConstructor::public(
+            function(vec![data(), byte_array()], byte_array()),
+            ValueConstructorVariant::ModuleFn {
+                name: "diagnostic".to_string(),
+                field_map: None,
+                module: "".to_string(),
+                arity: 2,
+                location: Span::empty(),
+                builtin: None,
+            },
+        ),
+    );
+
     // always
     let always_a_var = generic_var(id_gen.next());
     let always_b_var = generic_var(id_gen.next());
@@ -919,7 +1016,10 @@ pub fn from_default_function(builtin: DefaultFunction, id_gen: &IdGenerator) ->
     )
 }
 
-pub fn prelude_functions(id_gen: &IdGenerator) -> IndexMap<FunctionAccessKey, TypedFunction> {
+pub fn prelude_functions(
+    id_gen: &IdGenerator,
+    module_types: &HashMap<String, TypeInfo>,
+) -> IndexMap<FunctionAccessKey, TypedFunction> {
     let mut functions = IndexMap::new();
 
     // /// Negate the argument. Useful for map/fold and pipelines.
@@ -1239,6 +1339,230 @@ pub fn prelude_functions(id_gen: &IdGenerator) -> IndexMap<FunctionAccessKey, Ty
         },
     );
 
+    functions.insert(
+        FunctionAccessKey {
+            module_name: "".to_string(),
+            function_name: "enumerate".to_string(),
+        },
+        aiken_fn!(
+            &module_types,
+            &id_gen,
+            r#"
+                fn enumerate(
+                  self: List<a>,
+                  zero: b,
+                  with: fn(a, b) -> b,
+                  last: fn(a, b) -> b,
+                ) -> b {
+                  when self is {
+                    [] -> zero
+                    [x] -> last(x, zero)
+                    [x, ..xs] -> with(x, enumerate(xs, zero, with, last))
+                  }
+                }
+            "#
+        ),
+    );
+
+    functions.insert(
+        FunctionAccessKey {
+            module_name: "".to_string(),
+            function_name: "encode_base16".to_string(),
+        },
+        aiken_fn!(
+            &module_types,
+            &id_gen,
+            r#"
+                use aiken/builtin
+
+                fn encode_base16(bytes: ByteArray, ix: Int, builder: ByteArray) -> ByteArray {
+                  if ix < 0 {
+                    builder
+                  } else {
+                    let byte = builtin.index_bytearray(bytes, ix)
+                    let msb = byte / 16
+                    let lsb = byte % 16
+                    let builder =
+                      builtin.cons_bytearray(
+                        msb + if msb < 10 {
+                          48
+                        } else {
+                          55
+                        },
+                        builtin.cons_bytearray(
+                          lsb + if lsb < 10 {
+                            48
+                          } else {
+                            55
+                          },
+                          builder,
+                        ),
+                      )
+                    encode_base16(bytes, ix - 1, builder)
+                  }
+                }
+            "#
+        ),
+    );
+
+    functions.insert(
+        FunctionAccessKey {
+            module_name: "".to_string(),
+            function_name: "do_from_int".to_string(),
+        },
+        aiken_fn!(
+            &module_types,
+            &id_gen,
+            r#"
+                use aiken/builtin
+
+                fn do_from_int(i: Int, digits: ByteArray) -> ByteArray {
+                  if i <= 0 {
+                    digits
+                  } else {
+                    do_from_int(
+                      builtin.quotient_integer(i, 10),
+                      builtin.cons_bytearray(builtin.remainder_integer(i, 10) + 48, digits),
+                    )
+                  }
+                }
+            "#
+        ),
+    );
+
+    functions.insert(
+        FunctionAccessKey {
+            module_name: "".to_string(),
+            function_name: "from_int".to_string(),
+        },
+        aiken_fn!(
+            &module_types,
+            &id_gen,
+            r#"
+                use aiken/builtin
+
+                /// Encode an integer into UTF-8.
+                fn from_int(i: Int, digits: ByteArray) -> ByteArray {
+                  if i == 0 {
+                    builtin.append_bytearray(#"30", digits)
+                  } else if i < 0 {
+                    builtin.append_bytearray(#"2d", from_int(-i, digits))
+                  } else {
+                    do_from_int(
+                      builtin.quotient_integer(i, 10),
+                      builtin.cons_bytearray(builtin.remainder_integer(i, 10) + 48, digits),
+                    )
+                  }
+                }
+            "#
+        ),
+    );
+
+    functions.insert(
+        FunctionAccessKey {
+            module_name: "".to_string(),
+            function_name: "diagnostic".to_string(),
+        },
+        aiken_fn!(
+            &module_types,
+            &id_gen,
+            r#"
+              use aiken/builtin
+
+              fn diagnostic(self: Data, builder: ByteArray) -> ByteArray {
+                builtin.choose_data(
+                  self,
+                  {
+                    let Pair(constr, fields) = builtin.un_constr_data(self)
+
+                    let builder =
+                      when fields is {
+                        [] -> builtin.append_bytearray(#"5b5d29", builder)
+                        _ -> {
+                          let bytes =
+                            enumerate(
+                              fields,
+                              builtin.append_bytearray(#"5d29", builder),
+                              fn(e: Data, st: ByteArray) {
+                                diagnostic(e, builtin.append_bytearray(#"2c20", st))
+                              },
+                              fn(e: Data, st: ByteArray) { diagnostic(e, st) },
+                            )
+                          builtin.append_bytearray(#"5b5f20", bytes)
+                        }
+                      }
+
+                    let constr_tag =
+                      if constr < 7 {
+                        121 + constr
+                      } else if constr < 128 {
+                        1280 + constr - 7
+                      } else {
+                        fail @"What are you doing? No I mean, seriously."
+                      }
+
+                    builder
+                      |> builtin.append_bytearray(#"28", _)
+                      |> from_int(constr_tag, _)
+                  },
+                  {
+                    let elems = builtin.un_map_data(self)
+                    when elems is {
+                      [] -> builtin.append_bytearray(#"7b7d", builder)
+                      _ -> {
+                        let bytes =
+                          enumerate(
+                            elems,
+                            builtin.append_bytearray(#"207d", builder),
+                            fn(e: Pair<Data, Data>, st: ByteArray) {
+                              let value = diagnostic(e.2nd, builtin.append_bytearray(#"2c20", st))
+                              diagnostic(e.1st, builtin.append_bytearray(#"3a20", value))
+                            },
+                            fn(e: Pair<Data, Data>, st: ByteArray) {
+                              let value = diagnostic(e.2nd, st)
+                              diagnostic(e.1st, builtin.append_bytearray(#"3a20", value))
+                            },
+                          )
+                        builtin.append_bytearray(#"7b5f20", bytes)
+                      }
+                    }
+                  },
+                  {
+                    let elems = builtin.un_list_data(self)
+                    when elems is {
+                      [] -> builtin.append_bytearray(#"5b5d", builder)
+                      _ -> {
+                        let bytes =
+                          enumerate(
+                            elems,
+                            builtin.append_bytearray(#"5d", builder),
+                            fn(e: Data, st: ByteArray) {
+                              diagnostic(e, builtin.append_bytearray(#"2c20", st))
+                            },
+                            fn(e: Data, st: ByteArray) { diagnostic(e, st) },
+                          )
+                        builtin.append_bytearray(#"5b5f20", bytes)
+                      }
+                    }
+                  },
+                  self
+                    |> builtin.un_i_data
+                    |> from_int(builder),
+                  {
+                    let bytes = builtin.un_b_data(self)
+                    bytes
+                      |> encode_base16(
+                          builtin.length_of_bytearray(bytes) - 1,
+                          builtin.append_bytearray(#"27", builder),
+                        )
+                      |> builtin.append_bytearray(#"6827", _)
+                  },
+                )
+              }
+            "#
+        ),
+    );
+
     functions
 }
 
diff --git a/crates/aiken-lang/src/lib.rs b/crates/aiken-lang/src/lib.rs
index 5f52ceb7..2910c3f3 100644
--- a/crates/aiken-lang/src/lib.rs
+++ b/crates/aiken-lang/src/lib.rs
@@ -31,5 +31,36 @@ impl IdGenerator {
     }
 }
 
+#[macro_export]
+macro_rules! aiken_fn {
+    ($module_types:expr, $id_gen:expr, $src:expr) => {{
+        let (untyped_module, _) = $crate::parser::module($src, $crate::ast::ModuleKind::Lib)
+            .expect("failed to parse module.");
+
+        let module_name = "";
+
+        let mut warnings = vec![];
+
+        let typed_module = untyped_module
+            .infer(
+                $id_gen,
+                $crate::ast::ModuleKind::Lib,
+                module_name,
+                $module_types,
+                $crate::ast::Tracing::silent(),
+                &mut warnings,
+            )
+            .unwrap();
+
+        if let Some($crate::ast::Definition::Fn(typed_fn)) =
+            typed_module.definitions.into_iter().last()
+        {
+            typed_fn
+        } else {
+            unreachable!()
+        }
+    }};
+}
+
 #[cfg(test)]
 mod tests;
diff --git a/crates/aiken-lang/src/tipo.rs b/crates/aiken-lang/src/tipo.rs
index f29257c3..7b8274cf 100644
--- a/crates/aiken-lang/src/tipo.rs
+++ b/crates/aiken-lang/src/tipo.rs
@@ -12,10 +12,10 @@ use itertools::Itertools;
 use std::{cell::RefCell, collections::HashMap, ops::Deref, rc::Rc};
 use uplc::{ast::Type as UplcType, builtins::DefaultFunction};
 
-mod environment;
+pub(crate) mod environment;
 pub mod error;
 mod exhaustive;
-mod expr;
+pub(crate) mod expr;
 pub mod fields;
 mod hydrator;
 mod infer;
diff --git a/crates/aiken-lang/src/tipo/expr.rs b/crates/aiken-lang/src/tipo/expr.rs
index cd6cc184..697d676b 100644
--- a/crates/aiken-lang/src/tipo/expr.rs
+++ b/crates/aiken-lang/src/tipo/expr.rs
@@ -96,7 +96,7 @@ pub(crate) fn infer_function(
 
     let preregistered_fn = environment
         .get_variable(name)
-        .expect("Could not find preregistered type for function");
+        .unwrap_or_else(|| panic!("Could not find preregistered type for function: {name}"));
 
     let field_map = preregistered_fn.field_map().cloned();
 
@@ -1797,7 +1797,7 @@ impl<'a, 'b> ExprTyper<'a, 'b> {
         })
     }
 
-    fn infer_fn(
+    pub fn infer_fn(
         &mut self,
         args: Vec<UntypedArg>,
         expected_args: &[Rc<Type>],
@@ -2435,9 +2435,12 @@ impl<'a, 'b> ExprTyper<'a, 'b> {
                 tipo: string(),
                 value: if ix == 0 { ": " } else { ", " }.to_string(),
             };
-            typed_arguments.into_iter().enumerate().fold(label, |text, (ix, arg)| {
-                append_string_expr(append_string_expr(text, delimiter(ix)), arg)
-            })
+            typed_arguments
+                .into_iter()
+                .enumerate()
+                .fold(label, |text, (ix, arg)| {
+                    append_string_expr(append_string_expr(text, delimiter(ix)), arg)
+                })
         };
 
         let then = self.infer(then)?;
@@ -2813,7 +2816,8 @@ pub fn ensure_serialisable(is_top_level: bool, t: Rc<Type>, location: Span) -> R
 }
 
 pub fn append_string_expr(left: TypedExpr, right: TypedExpr) -> TypedExpr {
-    let value_constructor = from_default_function(DefaultFunction::AppendString, &IdGenerator::new());
+    let value_constructor =
+        from_default_function(DefaultFunction::AppendString, &IdGenerator::new());
     let append_string = TypedExpr::ModuleSelect {
         location: Span::empty(),
         tipo: value_constructor.tipo,
@@ -2827,13 +2831,11 @@ pub fn append_string_expr(left: TypedExpr, right: TypedExpr) -> TypedExpr {
         // So this is merely a small work-around for convenience. The proper way here would be to
         // pull the function definition for append_string from the pre-registered builtins
         // functions somewhere in the environment.
-        constructor: value_constructor
-            .variant
-            .to_module_value_constructor(
-                string(),
-                BUILTIN,
-                &DefaultFunction::AppendString.aiken_name(),
-            ),
+        constructor: value_constructor.variant.to_module_value_constructor(
+            string(),
+            BUILTIN,
+            &DefaultFunction::AppendString.aiken_name(),
+        ),
     };
 
     TypedExpr::Call {
diff --git a/crates/aiken-project/src/blueprint/snapshots/aiken_project__blueprint__validator__tests__free_vars.snap b/crates/aiken-project/src/blueprint/snapshots/aiken_project__blueprint__validator__tests__free_vars.snap
index af354a21..8f64d017 100644
--- a/crates/aiken-project/src/blueprint/snapshots/aiken_project__blueprint__validator__tests__free_vars.snap
+++ b/crates/aiken-project/src/blueprint/snapshots/aiken_project__blueprint__validator__tests__free_vars.snap
@@ -9,7 +9,7 @@ Schema {
             Var {
                 tipo: RefCell {
                     value: Generic {
-                        id: 35,
+                        id: 64,
                     },
                 },
                 alias: None,
diff --git a/crates/aiken-project/src/lib.rs b/crates/aiken-project/src/lib.rs
index 93196f5f..6efab615 100644
--- a/crates/aiken-project/src/lib.rs
+++ b/crates/aiken-project/src/lib.rs
@@ -130,7 +130,7 @@ where
         module_types.insert("aiken".to_string(), builtins::prelude(&id_gen));
         module_types.insert("aiken/builtin".to_string(), builtins::plutus(&id_gen));
 
-        let functions = builtins::prelude_functions(&id_gen);
+        let functions = builtins::prelude_functions(&id_gen, &module_types);
 
         let data_types = builtins::prelude_data_types(&id_gen);
 
diff --git a/crates/aiken-project/src/snapshots/aiken_project__export__tests__cannot_export_generics.snap b/crates/aiken-project/src/snapshots/aiken_project__export__tests__cannot_export_generics.snap
index 69be98f0..32ab8881 100644
--- a/crates/aiken-project/src/snapshots/aiken_project__export__tests__cannot_export_generics.snap
+++ b/crates/aiken-project/src/snapshots/aiken_project__export__tests__cannot_export_generics.snap
@@ -9,7 +9,7 @@ Schema {
             Var {
                 tipo: RefCell {
                     value: Generic {
-                        id: 35,
+                        id: 64,
                     },
                 },
                 alias: None,
diff --git a/crates/aiken-project/src/test_framework.rs b/crates/aiken-project/src/test_framework.rs
index a9ccebb9..15d1f57d 100644
--- a/crates/aiken-project/src/test_framework.rs
+++ b/crates/aiken-project/src/test_framework.rs
@@ -1328,7 +1328,7 @@ mod test {
                 .last()
                 .expect("No test found in declared src?");
 
-            let mut functions = builtins::prelude_functions(&id_gen);
+            let mut functions = builtins::prelude_functions(&id_gen, &module_types);
             let mut data_types = builtins::prelude_data_types(&id_gen);
             ast.register_definitions(&mut functions, &mut data_types);
 
diff --git a/crates/aiken-project/src/tests/mod.rs b/crates/aiken-project/src/tests/mod.rs
index 94ddf664..d0967542 100644
--- a/crates/aiken-project/src/tests/mod.rs
+++ b/crates/aiken-project/src/tests/mod.rs
@@ -46,7 +46,7 @@ impl TestProject {
         module_types.insert("aiken".to_string(), builtins::prelude(&id_gen));
         module_types.insert("aiken/builtin".to_string(), builtins::plutus(&id_gen));
 
-        let functions = builtins::prelude_functions(&id_gen);
+        let functions = builtins::prelude_functions(&id_gen, &module_types);
         let data_types = builtins::prelude_data_types(&id_gen);
 
         TestProject {