ABI Layer 2: prove C-binding signature preservation — flagship Idris2 proof#36
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Add Nimiser.ABI.Semantics, a machine-checked semantic proof that the Nim->C code generator preserves source signatures: same name, same arity, and every argument/return type lowered by the canonical injective nimToC mapping. An arity or type mismatch is unrepresentable as a SigPreserved witness. Contents: - Faithful model: NimT / CT type universes, NimSig / CSig signatures, total nimToC lowering, genBinding code generator. - Headline property SigPreserved with no constructor for any mismatch. - genBindingPreserves: the generator ALWAYS preserves (soundness). - nimToCInjective: the lowering is injective (non-vacuity engine). - decSigPreserved: sound + complete Dec decision procedure. - certifyBinding + certifyBindingSound tied to the project Result type; generatedAlwaysCertifies corollary. - Positive control samplePreserved (explicit witness) and three negative controls (wrong return type, wrong arity, wrong arg type), all machine-checked. Build: idris2 --build nimiser-abi.ipkg exits 0, zero warnings. Adversarial false proof (claiming a type-mismatched binding is preserved) is rejected by the type-checker, confirming non-vacuity. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01A6PSzJWpRxtzGDjUCEh7Mx
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Summary
Raises nimiser's Idris2 ABI to Layer 2 with its first flagship semantic proof. nimiser's headline is generating high-performance C libraries via Nim metaprogramming; the correctness obligation is that the generated C binding preserves the source signature — arity and per-argument type lowering. This proves
SigPreservedwith a sound+completeDec, so an arity/type mismatch is unrepresentable.Mirrors the estate flagship-proof pattern:
NimSig/CSigmodel,ArgsLower/SigPreservedpropositions, sound+completeDec, certifier proven sound, positive + negative controls.Changes
src/interface/abi/Nimiser/ABI/Semantics.idr— type loweringArgsLower,SigPreserved, sound+complete decision,certifyBinding/soundness, positive + negative controls.nimiser-abi.ipkg.RSR Quality Checklist
Required
As Applicable
Testing
Verified with Idris2 0.7.0:
idris2 --build nimiser-abi.ipkg→ exit 0, zero warnings. Adversarial check: a deliberately-false proof was rejected.build/removed.🤖 Generated with Claude Code
https://claude.ai/code/session_01A6PSzJWpRxtzGDjUCEh7Mx
Generated by Claude Code