Mix

Mix is a lightweight orchestration language for controlling distributed systems: a pure-Rust, ARexx-inspired scripting language and interactive shell with first-class network messaging built into the grammar. It runs as an ordinary scripting language, as a login shell, and as a supervised mesh citizen — and command results come back as structured data, never $? string soup.

Controlling systems across many machines normally means stitching together shell scripts, SSH, Ansible, REST/gRPC clients, message queues, and hand-rolled networking — each its own glue, its own failure mode, its own mental overhead. Mix makes network communication a core part of the language rather than something bolted on, so coordinating remote machines and services feels like writing a plain local script. It is the agent-operable control surface for the cosmix substrate.

The ARexx model from the 1987 Amiga was simple and powerful: every app is a named, addressable port, and one script orchestrates across all of them. Mix carries that ergonomic precedent forward onto a WireGuard mesh of Rust-native daemons with AMP markdown framing. Built for the cosmix substrate, Mix is its ARexx-equivalent and primary control surface. Lua was the original implementation sketch — it was deprecated and fully removed once Mix reached parity. Today Mix lives as two crates: cosmix-lib-mix (the interpreter) and cosmix-mix (the mix binary).

Source text flows through a three-stage pipeline. The lexer tokenises sigils, ${var} interpolation, heredocs, numbers, comments, and the AMP keywords. The parser builds the AST, handling postfix chains so $users.sort_by(...).take(10) parses correctly. The evaluator walks the tree single-threaded — on handlers serialize, one at a time, with events queued FIFO. In shell contexts a classifier decides whether a line is a shell command or a Mix statement — which is why bare x = 1 is misread, and every variable needs the $ sigil.

Sigils & operators at a glance

A terse lambda inside a higher-order builtin, an AMP send per node, and a structured result — no socket code, no retry loop, no serialization. This is the whole program.

-- ping a list of nodes over the AMP mesh, keep the live ones
$nodes = ["node1", "node2", "node3", "node4"]

-- a multi-statement probe must be var-bound before a HOF
$probe = function($n)
    send ("noded." .. $n .. ".amp") noded.ping timeout=2000
    return { name: $n, up: ($rc == 0) }
end

$results = map($nodes, $probe)
$live    = filter($results, fn($r) = $r["up"])

print(length($live) .. " of " .. length($nodes) .. " nodes up")