p_runtime

Runtime support library for P programs compiled to Elixir / the BEAM by the P compiler's Elixir backend.

P models communicating state machines that exchange asynchronous, typed events — a shape the BEAM was built for. The Elixir backend generates one :gen_statem per P machine; this library carries the cross-cutting pieces that do not vary with the .p source:

• Registry — addresses machines by their P name rather than pid.
• Trace — an in-memory, ordered recorder of runtime events, used by tests to assert a program's observable event trace.
• Spawner — serializes new MachineName(args) so id allocation is race-free.
• Specs — the spec-monitor subscription table and the synchronous fan-out of observed events.
• Log — emits each trace entry as a structured, PObserve-friendly key=value line.
• PRuntime helpers — goto/halt/raise_event/defer/ignore build the :gen_statem return tuples, send_event/announce are the (halt-aware, spec-fan-out) delivery wrappers, and created/entered/dequeued/observes record the trace and register monitors.

Logging is a runtime concern here, never inline in generated code — mirroring how PChecker's C# runtime logs as a side effect of base-class operations.

Status

Through M7: machine creation, state entry, goto, raise halt, payloads/types (including any), cross-machine sends (new + registry), defer/ignore, non-halt raise, spec monitors with synchronous announce/send fan-out plus a PObserve-compatible key=value log shape, and faithful failure surfacing — an unhandled event raises PRuntime.UnhandledEvent (rather than being dropped) and an abnormal process crash is recorded/logged via terminated/3. Foreign types/functions (M6) run entirely in the host's PForeign module. A Hex release is deferred; depend on this library via its GitHub ref for now.

Usage

Add as a dependency of a generated P/Elixir project (or its host):

def deps do
  [{:p_runtime, "~> 0.1"}]
end

The library starts its own supervision tree (Registry + Trace + Specs + Spawner) on boot.

Development

mix deps.get
mix compile
mix test