Monorepo: golang-lean (TGC) + octive-lean (TOC) + tsm-lean (TSM) + common-lean (cross-language apex).
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Maximus Gorog 878a84e072 Add Tiny Go Core (TGC): kernel calculus with proven determinism.
GolangLean/Core/ holds a small calculus that surface Go is intended to
desugar into. Three files:

  Syntax.lean       - Term, BinOp; thirteen syntactic forms covering
                      let-binding, lambda, application, references
                      (Go's & / *), conditionals, sequencing.

  Semantics.lean    - Value, EnvList, Heap, BinOp.apply, BigStep relation.
                      Heap is Array Value; references are indices.
                      Closures capture EnvList lexically, as in Go.
                      Fourteen big-step constructors, one per syntactic form
                      (with ifte split into ifTR / ifFR).

  Determinism.lean  - theorem BigStep.deterministic:
                        BigStep h env e v1 h1 -> BigStep h env e v2 h2 ->
                        v1 = v2 /\ h1 = h2
                      Proof by induction on the first derivation, case
                      analysis on the second. The ifTR/ifFR cross-cases
                      close by contradiction via Bool.noConfusion.

No sorries, no axioms, no admits. The kernel is small enough to extend
compositionally: each new syntactic form adds one constructor and one
case to each proof. Type system and concurrency layer come later.

Strategic note: this kernel is shaped so the same construction will
work for any sequential calculus. When octive-lean grows a parallel
Tiny Octave Core, the determinism proof's structure will line up
case-for-case where the languages share constructors. That alignment
is the seed of the cross-language layer.
2026-05-10 02:23:58 -06:00
corpus Initial scaffold: Lean 4 reimplementation of Go. 2026-05-10 02:12:19 -06:00
GolangLean Add Tiny Go Core (TGC): kernel calculus with proven determinism. 2026-05-10 02:23:58 -06:00
.gitignore Initial scaffold: Lean 4 reimplementation of Go. 2026-05-10 02:12:19 -06:00
CorpusCheck.lean Initial scaffold: Lean 4 reimplementation of Go. 2026-05-10 02:12:19 -06:00
GolangLean.lean Add Tiny Go Core (TGC): kernel calculus with proven determinism. 2026-05-10 02:23:58 -06:00
justfile Initial scaffold: Lean 4 reimplementation of Go. 2026-05-10 02:12:19 -06:00
lake-manifest.json Initial scaffold: Lean 4 reimplementation of Go. 2026-05-10 02:12:19 -06:00
lakefile.toml Initial scaffold: Lean 4 reimplementation of Go. 2026-05-10 02:12:19 -06:00
lean-toolchain Initial scaffold: Lean 4 reimplementation of Go. 2026-05-10 02:12:19 -06:00
Main.lean Initial scaffold: Lean 4 reimplementation of Go. 2026-05-10 02:12:19 -06:00
README.md Initial scaffold: Lean 4 reimplementation of Go. 2026-05-10 02:12:19 -06:00

golang-lean

A Lean 4 reimplementation of the Go programming language — using the upstream reference compiler/parser as the source of truth, the way octive-lean uses GNU Octave.

Built parallel to octive-lean. Goals:

  1. Working Go interpreter for a useful subset (start: pure Go, no goroutines).
  2. Formal semantics layered on top: BigStep / PureEval / ValueEquiv so proofs about Go programs are first-class.
  3. Cross-language layer — once both this and octive-lean have a real evaluator and big-step semantics, factor a shared core out of two concrete points rather than guessing the abstraction in advance.

Build

lake build

Requires the Lean toolchain pinned in lean-toolchain. elan will pick it up automatically.

Run

# REPL stub
lake exe golang-lean

# Run a .go script (not yet implemented)
lake exe golang-lean path/to/script.go

# Verify the corpus against expected outputs
lake build corpus-check
lake exe corpus-check

Layout

Path What's there
GolangLean/ Library: Token, Scanner, AST, Parser, Value, Env, Eval, Builtins, REPL, BigStep, PureEval, ValueEquiv, Error
Main.lean Entry point — REPL or file runner
CorpusCheck.lean Test driver for corpus/
corpus/ .go test cases paired with .expected outputs
go-upstream/ Shallow clone of golang/go (gitignored, used as reference)

Status

Scaffold. Module skeleton in place. Token and AST are real ports of go/token and go/ast. Scanner / Parser / Eval are stubs that throw notImpl so the project compiles.

Next:

  1. Implement Scanner.scan against go-upstream/src/go/scanner/scanner.go.
  2. Implement Parser.parseFile recursive-descent against go-upstream/src/go/parser/parser.go.
  3. Implement Eval for the pure subset (no goroutines, no defer, no panic/recover).
  4. Mirror octive-lean's BigStep / ValueEquiv triple.

Reference

go-upstream/ is a shallow clone of https://github.com/golang/go. Key paths:

Path What's there
go-upstream/src/go/token/ Token kinds, position tracking
go-upstream/src/go/scanner/ Lexer
go-upstream/src/go/ast/ AST node types
go-upstream/src/go/parser/ Recursive-descent parser
go-upstream/src/go/types/ Type-checker (later)
go-upstream/src/runtime/ Runtime / scheduler / GC (much later)