[GHC] #1897: Type families: type signature rejected

[GHC]

#1897: Type families: type signature rejected
-------------------------------------+--------------------------------------
 Reporter:  guest                    |          Owner:  chak       
     Type:  bug                      |         Status:  reopened   
 Priority:  normal                   |      Milestone:  6.10 branch
Component:  Compiler (Type checker)  |        Version:  6.9        
 Severity:  normal                   |     Resolution:             
 Keywords:                           |     Difficulty:  Unknown    
 Testcase:                           |   Architecture:  x86        
       Os:  Linux                    |  
-------------------------------------+--------------------------------------
Changes (by simonpj):

  * priority:  low => normal

Comment:

 See also #2157 and #2569.  And Ganesh's email http://www.mail-archive.com
 /haskell-cafe at haskell.org/msg39593.html

 We're now convinced that
   * There is really no good way to check the type of functions like
 `isValid`
   * The right thing to do is to reject the type as ambiguous, whether it
 is inferred or checked.  So the program would be rejected either way.

 Simon

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/1897#comment:6>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler