[GHC] #785: Allow partial application of type synonyms

[GHC]

#785: Allow partial application of type synonyms
----------------------------------------+-----------------------------------
  Reporter:  Bulat.Ziganshin at gmail.com  |          Owner:         
      Type:  feature request            |         Status:  new    
  Priority:  low                        |      Milestone:         
 Component:  Compiler                   |        Version:  6.4.2  
  Severity:  normal                     |     Resolution:         
  Keywords:                             |             Os:  Unknown
Difficulty:  Unknown                    |   Architecture:  Unknown
----------------------------------------+-----------------------------------
Changes (by simonpj):

  * priority:  normal => low
  * summary:  partial application of type function => Allow partial
              application of type synonyms

Comment:

 The error message is:
 {{{
 kinds.hs:5:0:
     Type synonym `IOUArray' should have 2 arguments, but has been given 0
     In the type synonym declaration for `DynamicIOUArray'
 }}}
 and that's an absolutely correct error message according to the Haskell
 language design.

 Adding fully fledged lambdas at the type level means adding higher-order
 unification, which is a huge can of worms. I don't think we are likely to
 implement this any time soon; mainly because it's not at clear what the
 design would be, and how it would interact with type inference.

 Meanwhile I bet Oleg has ideas for how to code up what you want in Haskell
 as it is.

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/785>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler