v1.0-RC2 — pre-alpha

Mighty — Agent-first systems programming language

An agent-first systems programming language. Statically typed, ownership-based, with first-class agents, protocols, capabilities and effects. Compiles to native + WebAssembly.

View on GitHub →Read the docs

Hello, Mighty

A small program, a real compiler.

mty new scaffolds a project. mty check runs the full pipeline — lex, parse, lower, type-check, borrow-check. mty run JITs via Cranelift, with a tree-walking interpreter as fallback.

src/main.mtyMIGHTY

fn main() {
  log("hello, Mighty")
}

Features

A real compiler stack, not a toy.

Type system

Hindley–Milner inference with bidirectional checking. Generics with monomorphization, trait dispatch, dyn Trait fat pointers. ? propagation for Result. Effect system + capabilities (fs, net, time, rand, model). Formal Sendable trait for cross-agent message soundness.

Ownership & borrow

Ownership + move + borrow + affine + arena tracking. Field-level borrow Places with NLL last-use deactivation — the borrow checker that knows when you're done.

Concurrency

Tokio-backed runtime with mailboxes, supervisors, deadline timers. Multi-core scheduler with per-worker tokio runtimes, crossbeam-deque work-stealing, affinity hints. Cooperative mid-turn cancellation. Deterministic-execution mode. Per-handler memory + tick budgets.

Codegen

Cranelift JIT + AOT object emission by default. LLVM backend behind --features llvm. Wasm core module + Component Model emission via wit-component. DWARF v4 debug info, Wasm source maps, and a name section.

Tooling

mty lsp ships an LSP 3.17 server. mty pkg is a real package manager: resolver, lockfile, GitHub-Releases registry, signed sidecars. mty doc generates markdown/HTML with a search index. mty fmt is idempotent under fuzz.

Self-hosting

Lexer, ~1.9 KLOC parser subset, HIR lowering, minimal typeck, and MtyIR lowering are written in Mighty itself, exercised against examples 01–05. 40 self-host tests passing. A pure-Python second front-end lives in impl-py/ — 135 tests, 20/20 examples.

Install

Build from source.

There is no released binary yet — Mighty is pre-alpha. MSRV is Rust 1.85. Treat the language as unstable, and file issues for everything that surprises you.

github.com/hassard0/Mighty →

$ shellMSRV 1.85

cargo install --git https://github.com/hassard0/Mighty mty-cli
mty new hello && cd hello
mty run src/main.mty
# → hello, Mighty

The CLI

One binary, mty.

mty check	lex, parse, lower, type-check, borrow-check
mty run	JIT via Cranelift (interpreter fallback)
mty build	native object + linker, or --target wasm32-wasi
mty fmt	canonical Wadler/Lindig formatter
mty dump --sir	inspect the mid-level IR
mty explain MTxxxx	one-paragraph explanation of any diagnostic

1,112

tests across the workspace

clippy warnings under strict pedantic

normative conformance cases (91% coverage)

v1.0-RC2

spec frozen, freeze target 2026-09-01

To v1.0

Spec frozen at RC2. Three blockers.

01A second independent compiler implementation (RFC-007).
02The six RFC 30-day comment windows (RFC-001…RFC-006).
03A published normative conformance suite.

Proposed freeze date — 2026-09-01.

Post-v1.0

On the longer horizon.

— Lossless live agent migration; per-message work-stealing.
— Polonius-style borrows; real cap-name resolution wiring.
— WASI Preview 2 + user-supplied WIT; DWARF v5.
— Effect-row polymorphism.
— Distributed agents; PGO / ThinLTO.