Bidirectional Type Checker

The compiler now includes a full bidirectional type checker built on Robinson unification. It eliminates Unknown types across the board — field access, empty collections, option literals, pipe receives, inspect arm bindings, and closure calls all get concrete types. The checker runs between analysis and codegen, producing a TypeEnv that downstream optimization passes use for better decisions.

Codegen Architecture Refactor

The monolithic codegen.rs (8,300 lines) has been split into 13 focused modules: context, detection, expr, stmt, peephole, program, ffi, marshal, policy, bindings, tce, and types. The public API is preserved via re-exports — no downstream breakage. The C backend (codegen_c.rs, 2,000 lines) was similarly split into emit, runtime, and types.

15 Codegen Optimizations

This release adds a battery of performance improvements:

  • Last-use clone elimination — skips .clone() when a value's last use is detected
  • Liveness-based move — backward dataflow analysis identifies variables that can be moved instead of cloned
  • Sentinel exit detection — eliminates redundant loop condition checks
  • Dead post-loop counter elimination — removes counter variables unused after loop exit
  • HashMap .get() for comparisons — avoids cloning map values just to compare them
  • String byte comparison — uses .as_bytes() for ASCII string equality
  • Self-append via write! — eliminates temporary allocations in string concatenation
  • Flattened string concatenation — chains of + on strings collapse into a single format!
  • Read-only &[T] borrows — call graph analysis identifies parameters that are never mutated
  • Vec::with_capacity — pre-allocates vectors when the size is known
  • assert_unchecked for proven bounds — removes redundant bounds checks
  • Raised inline threshold — more aggressive inlining for small functions
  • Power-of-2 modulo strength reduction — x % 2^n becomes x & (2^n - 1)
  • target-cpu=native — generated projects compile for the host CPU architecture
  • FxHashMap/FxHashSet — rustc-hash for faster integer-key hashing

New Language Features

  • Bitwise operators: x xor y, x shifted left by y, x shifted right by y
  • Break statement: Break. exits the innermost while loop
  • Unary NOT: not x for logical and bitwise negation
  • Generic function type parameters: polymorphic type variable declarations
  • Triple-quote strings: """multi-line""" with automatic indentation stripping
  • Scientific notation: 4.84e+00, 2.5e-2 in numeric literals

Analysis Infrastructure

Three new analysis passes power the optimization pipeline:

  • Call graph analysis (callgraph.rs) — whole-program call graph with Kosaraju SCC detection
  • Liveness analysis (liveness.rs) — backward dataflow for per-statement live-after sets
  • Read-only parameter inference (readonly.rs) — fixed-point iteration over the call graph

Testing

~392 new tests across 8 new test files covering the type checker, bitwise operations, break statements, codegen optimization, math builtins, string interpolation, and optimizer features. The benchmark suite expanded from ~6 to 30+ programs with multi-language implementations and correctness verification.