1 files changed, 37 insertions, 2 deletions
diff --git a/README.md b/README.md
index 722730f..5830918 100644
--- a/README.md
+++ b/README.md
@@ -2,12 +2,47 @@
 
 A place where I can make some bad decisions.
 
-Puck is an experimental, memory safe, strongly typed, imperative and functional programming language.
+Puck is an experimental, memory safe, structurally typed, imperative and functional programming language.
 It aims to be clean and succinct while performant: having the flexibility/metaprogramming of [Nim](https://nim-lang.org/) with the error handling of [Swift](https://www.swift.org/) and the performance/safety guarantees of [Rust](https://www.rust-lang.org/).
 
 You may judge for yourself if Puck meets these ideals.
 
-```puck
+```nim
+import std/tables
+
+module AST:
+  pub type Value = interface
+    func repr(self: Self): string
+  pub type Ident = string
+  pub type Expr = ref union
+    Literal: Value
+    Variable: Ident
+    Abstraction: struct[param: Ident, body: Expr]
+    Application: struct[body, arg: Expr]
+    Conditional: struct
+      cond, then_case, else_case: Expr
+
+  pub func eval(expr: Expr, context: var HashTable[Ident, ref Value]): Result[ref Value]
+    match expr
+      of Literal(value):
+        Okay(value)
+      of Variable(ident):
+        context.get(ident)
+      of Application{body, arg}:
+        if body of Abstraction{param, body as inner_body}:
+          context.set(param, eval(arg))
+          inner_body.eval(context)
+        else:
+          Error(InvalidExpr)
+      of Conditional{cond, then_case, else_case}:
+        if eval(cond, context):
+          then_case.eval(context)
+        else:
+          else_case.eval(context)
+      of _:
+        Error(InvalidExpr)
+
+AST.eval((λx.x) 413)
 ```
 
 ## Why Puck?