avoid sortedness errors with polymorphically let-bound constants #544
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mezpusz
reviewed
Apr 10, 2024
| // fast path for constants | ||
| // also avoids assertion failures below with $let-bound constants, | ||
| // which have arity 0 but their sort may contain sort variables (!) | ||
| if(!t->arity()) { |
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According to this paper, let binders can be non-constant as well. Not saying I have a better idea for now, just that in general we should expect this in other cases as well.
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Good catch. By some miracle we actually seem to parse and process these beasts correctly (which then triggers the old assertion again). They could even have type arguments. :-O
Proposal: flag let-bound symbols and exempt them from such assertions. This was my original idea but it seemed too heavy-handed for just constants.
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Fixes bug 1 of #542 by providing a fast path for constants in
getResultSortthat also does not assert a condition that isn't true for let-bound constants.A TFX1
$letmight capture sort variables. Consider e.g. polymorphic lists and the following axiom.In the expression
e,x: list(A). But this is a non-polymorphic constant (both term and type arity 0) with a variable in its result sort, whichSortHelperdoesn't like. It seems to be eliminated just fine in later FOOLing around.