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  • #7910

Closed
Open
Opened May 14, 2013 by trevor@trac-trevor

ConstraintKinds and reifyInstances

reifyInstances doesn't appear to know how to deal with a constraint that is just an alias. For example, the following prints (True,False):

{-# LANGUAGE ConstraintKinds #-}
{-# LANGUAGE TemplateHaskell #-}

import Language.Haskell.TH
import Language.Haskell.TH.Syntax

class C a
instance C Int

type D a = C a

main = print $(
  do isCInst <- isInstance ''C [ConT ''Int]
     isDInst <- isInstance ''D [ConT ''Int]
     lift (isCInst,isDInst))
Trac metadata
Trac field Value
Version 7.6.3
Type Bug
TypeOfFailure OtherFailure
Priority normal
Resolution Unresolved
Component Compiler
Test case
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Reference: ghc/ghc#7910