[GHC] #7021: Tuple (and other exotic predicates) not yet handled in Template Haskell

[GHC]

#7021: Tuple (and other exotic predicates) not yet handled in Template Haskell
------------------------------+---------------------------------------------
 Reporter:  goldfire          |          Owner:                                 
     Type:  feature request   |         Status:  new                            
 Priority:  normal            |      Component:  Template Haskell               
  Version:  7.5               |       Keywords:  ConstraintKinds TemplateHaskell
       Os:  Unknown/Multiple  |   Architecture:  Unknown/Multiple               
  Failure:  None/Unknown      |       Testcase:                                 
Blockedby:                    |       Blocking:                                 
  Related:                    |  
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 Say I make the following declarations:

 {{{
 {-# LANGUAGE ConstraintKinds #-}

 type IOable a = (Show a, Read a)

 foo :: IOable a => a
 foo = undefined
 }}}

 It is currently impossible to {{{reify}}} {{{foo}}} in Template Haskell.
 This also comes up when using nested lists of constraints in Template
 Haskell quotes.

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/7021>
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