[GHC] #7401: Can't derive instance for Eq when datatype has no constructor, while it is trivial do do so.

[GHC]

#7401: Can't derive instance for Eq when datatype has no constructor, while it is
trivial do do so.
---------------------------------+------------------------------------------
    Reporter:  jpbernardy        |       Owner:                           
        Type:  feature request   |      Status:  infoneeded               
    Priority:  normal            |   Milestone:  7.8.1                    
   Component:  Compiler          |     Version:  7.6.1                    
    Keywords:  deriving          |          Os:  Unknown/Multiple         
Architecture:  Unknown/Multiple  |     Failure:  GHC rejects valid program
  Difficulty:  Unknown           |    Testcase:                           
   Blockedby:                    |    Blocking:                           
     Related:                    |  
---------------------------------+------------------------------------------
Changes (by igloo):

  * status:  new => infoneeded
  * milestone:  => 7.8.1


Comment:

 jpbernardy, have you got an example of why this is useful please?

 Did you run into this in a real program?

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/7401#comment:4>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler