Bifrost

One CLI for every Shen port: run a program, eval an expression, or check that implementations print the same thing.

It is not a Shen runtime. It launches shen-cl, shen-go, shen-rust, shen-lua, and the others the way a user would, then diffs stdout.

The official kernel suites stay in each port. Bifrost asks a different question: do the ports agree?

The maintained adapters target ShenOSKernel 43.1. Shen-C pins v0.3.0's native RC backend and its separately maintained kernel lineage. Exact version checks select each adapter's declared kernel. See the 43.1 qualification and matrix gaps.

Install

go install github.com/pyrex41/bifrost@latest
# or
nix run github:pyrex41/bifrost -- impls

Default layout is sibling checkouts (../shen-go, ../shen-cl, …). Override with BIFROST_PORTS_ROOT. Nix (nix run .#env -- all -- bifrost) is how you get port toolchains, not just the CLI.

Use

bifrost run prog.shen [--impl shen-go]
bifrost eval -e '(+ 2 3)' [--impl shen-rust]
bifrost repl [--impl shen-cl]
bifrost impls --versions
bifrost use shen-go                 # default port
bifrost                             # run the agreement corpus

--impl wins, then ./.bifrost-impl, then ~/.config/bifrost/impl, then the first available port (prefers shen-cl).

Agreement corpus

go run .                            # FAIL → exit ≠ 0
go run . --impls shen-cl,shen-go,shen-rust
go run . --only hash-agrees-with-equality,freeze-in-lambda
go run . --heavy                    # also Yggdrasil stage-1 byte-identity

~70 cases in cases/*.json + programs/*.shen: arithmetic, lists, strings, closures, Prolog, trap-error, and ShenOSKernel 43.1 behavior any port should share (integer?, =, intern of "true", hash agreeing with =, tuples/vectors, put/get, freeze captured by a lambda).

A case is a golden expect: output or expect: agreement (all ports print the same normalised string). Details: docs/matrix.md.

Your own project: add bifrost.suite.json and run bifrost --suite PATH. See docs/suites.md.

More

CLI	docs/cli.md
Nix	docs/nix.md
Corpus and --shake	docs/matrix.md
Third-party suites	docs/suites.md
Canonical port tree	docs/port-layout.md

Yggdrasil is the companion shaker (bifrost --shake for stand-alone deploy artifacts).

License: Apache-2.0.