`mty run`¶

Compile a Mighty source file and execute it.

Slice 7 (v0.7.0-runtime): mty run defaults to the slice-7 runtime, a tokio-backed concurrent executor with mailboxes, supervisors, deadline timers, and budget/sandbox enforcement. Pass --legacy-interp to fall back to the slice-6 synchronous interpreter for diagnostic comparison.

Usage¶

mty run [--legacy-interp] <file>

<file> is a single .mty source file. Slice 7 does not yet support package-aware execution; only the items in the named file are visible.

Process model¶

mty run performs the full slice-1-through-slice-5 pipeline before executing:

Parse + lower to HIR
Type check
Effect inference + capability subsumption
Borrow check
MtyIR lowering
Runtime execution: build a Runtime, run main on the evaluator inside tokio::block_on, and run spawned agents on the runtime's per-agent task loops.

If any earlier stage reports an error, mty run prints diagnostics with source spans and exits 1.

Otherwise execution starts at the fn named main. main takes zero arguments today and may return:

() / Unit - exit 0
I32 or another integer - that value as the exit code
Result::Ok(...) - exit 0
Result::Err(...) - exit 1, with the err payload printed

A runtime trap (panic(msg), divide-by-zero, missing handler, and so on) prints trap SD5xxx: message to stderr and exits 1.

If the program has no fn main, mty run returns the runtime to shut down all agents and exits 0. This matches examples 07, 08, and 10, which lack a main in their canonical form.

Exit codes¶

Code	Meaning
0	Normal completion
1	Compile error, trap, or `Result::Err` from `main`
2	No `main` fn in a slice-6 (`--legacy-interp`) program
3	Interpreter step budget exceeded (default 5 000 000 steps)

Runtime environment variables¶

Variable	Effect
`MTY_TRACE=stderr`	emit JSON telemetry lines to stderr
`MTY_TRACE=file:/path`	append JSON telemetry to file
`MTY_RUNTIME_THREADS=N`	tokio worker thread count (default 1)
`MTY_DET_SEED=N`	reserved seed for deterministic mode
`MTY_HTTP_MOCK=1`	reserved skip-TCP-bind flag for tests

The legacy STARDUST_* spellings (STARDUST_TRACE, STARDUST_RUNTIME_THREADS, and so on) are still honoured for back-compat with v0.6-era deployments; the first lookup that falls through to a STARDUST_* name emits a one-shot deprecation warning on stderr.

Example¶

$ cat hello.mty
fn main() {
  log("hello, Mighty")
}

$ mty run hello.mty
hello, Mighty
$ echo $?
0

Spawn + ask an agent:

$ cat echoer.mty
protocol Echo { Ping(m: Str) -> Str }
agent Echoer: Echo { on Ping(m) -> m }

fn main() {
  let h = spawn Echoer()
  let r = h?Ping("hi")
  log(r)
}

$ mty run echoer.mty
hi

Effect handling¶

mty run JIT-compiles with Cranelift and falls back to the interpreter per-program for any stdlib surface that does not yet have native codegen. The fall-back is transparent: the program runs and produces the same result as --legacy-interp — you never see a crash for an unimplemented surface.

Lowered natively (run on the Cranelift path):

std.fs.* — read, read_to_string, read_dir / list_dir, write, exists, metadata, the read_dir iterator, and their documented aliases, via the runtime's native ABI symbols.
std.crypto digests — sha256, sha512, blake3, hmac_sha256.
std.encoding encoders — hex.encode, base64.encode, base64.encode_url_no_pad.

Interpreter-hosted (the whole program transparently falls back to the interpreter when one of these is called): std.url, std.uuid, std.regex, std.crypto AEAD (aes_gcm, chacha20_poly1305) and random_bytes, the std.encoding decoders, and other not-yet-native stdlib modules. These run with the same capability checks and behaviour as --legacy-interp; native codegen for them is incremental (see dev/history/releases/).

mty check <file> - parse + lower + type-check without executing
mty dump --sir <file> - print the MtyIR program
mty dump --hir <file> - print the lowered HIR
mty dump --ast <file> - print the AST item summary
mty explain SD5xxx - explain a runtime diagnostic

Future work¶

Forward command-line args to main(args: &[Str])
Honour environment variables when the program reads std.env
Wire automatic supervisor restart; the policy is in place, and the orchestrator lands with codegen
Native capability ABI for host-backed stdlib calls in JIT/AOT output

mty run¶