Map: core / IR

core/src/ir.rs is the call-by-push-value intermediate representation — the target of elaboration and the input to the evaluator.

The two categories:

• Val — inert data: Unit, String, Int, Float, Bool, lists, maps, thunks, variables. A value can never diverge or perform I/O.
• Comp — effectful, sequenced computation. Comp wraps a CompKind plus an optional Span for error reporting (synthetic nodes carry span: None). CompKind::Bind carries scheme: Option<Box<Scheme>> — the checker’s verdict, written onto each top-level name-bind by the annotation pass and None until it runs (session-scheme-continuity).

The checker’s mode verdict rides on the IR too, as ground annotations written by annotate (ir-pipespec-annotation). Because the inference pass is unconditional — every evaluated IR is annotated (unconditional-mode-pass) — the mode slots are not optional: “the checker has not run yet” is not a representable state.

• CompKind::Pipeline is a struct variant { stages, wires: Vec<Wire>, stage_types: Vec<Ty> } — one Wire and one Ty per stage, both parallel to stages. wires carries the ground byte channel; stage_types carries the inferred value type that flows out of each stage. The elaborator fills wires with Wire::EMPTY and stage_types with Unit placeholders that the annotation pass overwrites wherever inference visited (typecheck).
• CompKind::Bind carries rhs_output: ByteMode — the bound computation’s ground output mode, the one bit eval_bind_rhs reads to decide stdout capture.

A Wire { input, output } and ByteMode { Bytes, Empty } live in core/src/mode.rs: the two-valued image of a PipeSpec with the PipeMode::Var arm removed. The placeholder Wire::EMPTY is the same Var → Empty default the annotator writes for an unconstrained wire, so a hypothetical un-annotated path degrades to all-Empty rather than panics — but no such path survives the unconditional pass. The grounding rule runs once at annotation, so “annotations are ground” is a fact of the type rather than an invariant the reader must trust — the lattice’s polymorphism lives only in schemes on the checker side, never on a node the evaluator reads.

CommandName is the structured head for external dispatch (Bare / Path / TildePath). IrPattern = Pattern<Arc<Comp>> — the same Pattern shape as the AST, but map-pattern defaults are pre-elaborated computations, so no parser syntax leaks through (ir-pure-cbpv).

referenced_names (pub(crate)) collects a compiled program’s variable and command-head names in one exhaustive, wildcard-free walk — the use-observation signal the binding-lease ledger renews on (agent-binding-reaping).

This shape is what the prelude bake serialises with postcard; adding a field to CompKind, Val, or Pattern invalidates every emitted blob (see core and core/src/lib.rs). docs/SPEC.md gives the formal CBPV account.