wiki:RecordPatternMatching

Version 1 (modified by simonmar@…, 8 years ago) (diff)

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Section 3.17.2, "Informal Semantics of Pattern Matching", is a bit vague on matching record patterns. For example, see this GHC bug report:

http://cvs.haskell.org/trac/ghc/ticket/246

There are two possible ways forward:

  • Clarify the description to ratify GHC's behaviour, i.e. record fields are matched in the order written in the datatype. Pros: this is easier to implement, Cons: it is not quite as intuitive for the programmer.
  • Clarify the description to specify that fields are matched in the order written in the pattern.