Side-by-side comparisons of Go syntax with two Lean encodings:
* Surface AST (GolangLean.Expr) — mirrors go/ast.Node from upstream.
* Tiny Go Core (GolangLean.Core.Term) — kernel calculus with proven
operational + type semantics.
Twelve sections covering: literals, arithmetic, comparison, conditional,
variables/let-binding, functions/application, references/deref/assign,
sequencing. Each example includes a `#eval` running the term through
the proven Core.eval; output matches what's expected at run time.
Demonstrated programs:
- `(5 + 3) * 2` → 16
- `let x = 3 in let y = 7 in x < y` → true
- `(λ x. x*2) 21` → 42
- `let double = λ x. x*2 in double (double 5)` → 20
- `let p = &42 in *p = 100; *p` → 100 (heap: [vInt 100])
- higher-order: `(λ f. λ x. f (f x)) double 3` → 12
Each #eval is a runtime witness for a Core.BigStep derivation. Apply
Core.eval_sound to get a proof of the BigStep relation, and
Core.preservation to get the value's type.
Supporting changes:
- Added Repr instances for Core.Value and Core.EnvList (manual,
handling the mutual inductive — derive doesn't compose across the
mutual block).
- Added RosettaStone as a lean_lib in lakefile.toml.
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