PEGO
G150: Typed Left-Recursion Bodies
Eligible typed left-recursion leaders can inline matching expressions while retaining runtime seed growth.
Mechanism and Invariants
The runtime still owns leader invocation, growth, memoization, action and finish. The cut-free route requires a matching capture layout; unresolved or unsupported bodies remain general. Framed cuts and recovery use separately selected extensions.
Scope and State
Applied by default only to eligible generated typed Go bodies. Node parsing/recognition, closure, VMs and TypeScript retain their separate routes.
Reference Control
No generation option selects an alternative for this mechanism. Typed Go
output comes from the Flow IR printer, and its generated parsers are compared
with the engine oracle in the internal/engine tests.
Evidence and Implementation
Record 079 uses five same-generator direct/general pairs. Large action/capture LR fixtures measure 0.893 CodePoints and 0.943 Bytes; calculator ranges all cross parity. Large allocation counts remain unchanged. Results concern eligible leader-body inlining, with growth fixed, and do not establish benefits for every LR grammar.
Evidence records: 079.
Source owners: typed structural emitter, framed body emission.
The comparison policy distinguishes same-source controls, historical changes and full checkpoints.