fix: wary substitution + concrete subst parsing + de Bruijn shadowing - #19
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…Bruijn)
Port the substitution work from the Solidity extension to Rust:
- WarySubstOp / WaryClashFreeSubst: a non-rigid replacement (e.g. a program
variable) is no longer pushed across a modality, behind an update, or into
a transformer; such occurrences are kept and the substitution is left as a
residual (subst_to_eq can then Skolemize). Rigid replacements push as
before. WarySubstOp.SUBST replaces SubstOp.SUBST in the parser/notation.
- visitSubstitution_term: no longer throws "TODO @ DD" — a concrete
{\subst T x; t} phi declares its own de Bruijn bound variable and unbinds
afterwards.
- lookupVarfuncId: search bound variables innermost-first, so a shadowed
name binds to the innermost binder (\forall x; \forall x; p(x) — index 1).
WarySubstAndShadowingTest covers all three.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
This was referenced Jun 17, 2026
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What
Wary substitution + concrete subst parsing + a de Bruijn shadowing fix.
WaryClashFreeSubst/WarySubstOp: correct substitution under binders soshadowed variables are not captured (de Bruijn handling).
ExpressionBuilder: parse concrete substitutions.NotationInfo: pretty-print support.WarySubstAndShadowingTest.Foundational fix that the argument-sorts, casts and GUI PRs build on, so it is
sent first as its own PR (stacked underneath them).
Base:
rusty-dev.