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  • Glasgow Haskell CompilerGlasgow Haskell Compiler
  • GHCGHC
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  • #1330
Closed
Open
Issue created May 05, 2007 by Ian Lynagh <igloo@earth.li>@trac-igloo

Impredicativity bug: Church2 test gives a rather confusing error with the HEAD

The Church2 test gives a rather confusing error with the HEAD:

Church2.hs:27:14:
    Couldn't match expected type `CNat'
           against inferred type `(a -> a) -> a -> a'
      Expected type: CNat -> CNat
      Inferred type: CNat -> CNat
    In the first argument of `n', namely `(mul m)'
    In the expression: n (mul m) n1

In particular the lines

      Expected type: CNat -> CNat
      Inferred type: CNat -> CNat

are confusing, and I'm not sure why it's giving two expected/inferred pairs of types.

Trac metadata
Trac field Value
Version 6.7
Type Bug
TypeOfFailure OtherFailure
Priority normal
Resolution Unresolved
Component Compiler (Type checker)
Test case
Differential revisions
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Blocking
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Operating system Unknown
Architecture Unknown
Edited Mar 09, 2019 by Simon Peyton Jones
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