[GHC] #4271: Cannot declare multiparameter type class with TypeOperators.

[GHC]

#4271: Cannot declare multiparameter type class with TypeOperators.
---------------------------------+------------------------------------------
    Reporter:  Khudyakov         |       Owner:              
        Type:  bug               |      Status:  new         
    Priority:  normal            |   Component:  Compiler    
     Version:  6.12.3            |    Keywords:              
    Testcase:                    |   Blockedby:              
          Os:  Unknown/Multiple  |    Blocking:              
Architecture:  Unknown/Multiple  |     Failure:  None/Unknown
---------------------------------+------------------------------------------
 This code lead to error message: "Malformed instance header"
 {{{
 {-# LANGUAGE TypeOperators #-}
 {-# LANGUAGE MultiParamTypeClasses #-}

 class f :<: g

 instance () :<: ()
 }}}

 If instance declaration changed to code below it compiles just fine.
 {{{
 instance (:<:) () ()
 }}}

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/4271>
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