fix: reduce ambiguity of "final" in application type mismatch message#8322
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jrr6 merged 1 commit intoleanprover:masterfrom May 14, 2025
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fix: reduce ambiguity of "final" in application type mismatch message#8322jrr6 merged 1 commit intoleanprover:masterfrom
jrr6 merged 1 commit intoleanprover:masterfrom
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| e := e.setAppPPExplicit | ||
| let aType ← inferType a | ||
| throwError "Application type mismatch: In the application{indentExpr e}\nthe final argument{indentExpr a}\n{← mkHasTypeButIsExpectedMsg aType expectedType}" | ||
| -- Clarify that `a` is "last" only if it may be confused with some preceding argument; otherwise, |
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| -- Clarify that `a` is "last" only if it may be confused with some preceding argument; otherwise, | |
| -- Clarify that `a` is "last" only if it may not be confused with some preceding argument; otherwise, |
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This wording here is correct: we only want to explicitly label the argument as "last" if there's some argument before it to which it is identical ("last" is as in "the last among the arguments a"). If there's only one argument that's a, it's confusing to refer to the "last" one, since there's only one. ("May" in this comment is synonymous with "might," not "should.")
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This PR refines the new wording of the "application type mismatch" error message to avoid ambiguity in references to the "final" argument in a subexpression that may be followed by additional arguments.
It does so by replacing "final" with "last," rephrasing the message so that this adjective modifies the argument itself rather than the word "argument," and only displaying this wording when two arguments could be confused (determined by expression equality).
These changes were motivated by a report that in cases where a function application
f a b cfails to elaborate becausebis incorrectly typed, the existing error message's reference tobbeing the "final" argument in the applicationf a bmay create confusion because it is not the final argument in the full application expression.