PE Infrastructure

Three new LOGOS source programs power the Futamura projection pipeline:

  • PE BTI source (pe_bti_source.logos, 1215 LOC) — a binding-time improved partial evaluator. Renames internal predicates (isStatic → checkStatic, specResults → memoCache) and uses B-suffixed entry points (peExprB, peBlockB) to avoid name collisions during self-application. This is what Projection 2 produces as a compiler.
  • PE mini source (pe_mini_source.logos, 785 LOC) — a clean-room minimal partial evaluator with its own PEMiniState type (no specResults/onStack fields). Uses M-suffixed entry points (peExprM, peBlockM). This is what Projection 3 produces as a compiler generator.
  • Decompile source (decompile_source.logos, 645 LOC) — a source-level decompiler that converts PE output back to readable LOGOS.

Genuine Self-Application

The partial evaluator can now specialize itself. Key results verified by tests:

  • PE(pe_source, nano-PE(CInt(42))) produces "42" — The Trick demonstrated
  • PE(pe_source, pe_mini(5+3)) produces "8" — a real PE specializing a real PE
  • Projection 2 with dynamic target: PE produces residual code containing the dynamic target and no source PE function definitions

Critical fixes that enabled this: CMapGet folding for CNewVariant/CNew expressions, staticEnv seeding in all-static CCall, and isLiteral → isStaticValue promotion in CLet/CSet.

Reference Semantics

Collections now use Rc-based reference semantics throughout:

  • LogosSeq<T> wraps Rc<RefCell<Vec<T>>> — .clone() is O(1) shared reference, .deep_clone() copies data
  • LogosMap<K,V> wraps Rc<RefCell<FxHashMap<K,V>>> — same semantics
  • Interior mutability via RefCell::borrow_mut() — methods take &self
  • copy of in LOGOS source triggers .deep_clone() for value semantics where needed

PE Engine Improvements

  • specResults memoization activated with deep-cloned body results
  • makeKey collision fix — exprToKeyPart covers all CExpr variants with structural keys
  • MSG wiring — interner threaded through drive/generalize, msg() activated on whistle
  • BTA SCC wiring — analyze_with_sccs() called in optimize paths
  • isStatic expansion — CNew, CRange, CCopy recognized as static
  • Partially-static data — CLen folds CTuple, exprToVal handles CNewVariant/CNew
  • extractReturn sentinel — changed fallback from CInt(0) to CVar("__no_return__") to prevent silent miscompilation

Testing

~5,000 new Futamura projection tests across Sprints A–J, plus 191 lines of reference semantics E2E tests. All 4,513 tests pass with zero regressions.