racket / racket/redex

where/error gives uninformative error message

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Dominant language
Racket
Stars
112
Forks
42
PR merge metrics
No merged PRs in 30d

Description

Consider:

#lang racket
(require redex/reduction-semantics)
(define-language L)
(define-metafunction L
  [(test any)
   #f
   (where/error 1 any)])
(term (test 2))

Which gives the error message define-metafunction: where/error did not match. It would be more helpful if this error message include the term that failed to match and the what the call to the metafunction was (like side-condition).

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Research direction

Reproduce the issue with the provided #lang racket and redex/reduction-semantics example, then locate the implementation of where/error and define-metafunction. Compare its diagnostics with side-condition and make the failure report include the unmatched term and the metafunction call, as requested.

Written by the indexing model from the issue text.

Assessment

Domain
compilers
Issue type
Bug
Difficulty
3/5
Estimated time
1-2 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
45/100

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