[GHC] #633: add dataCast{1, 2} to Data instances of Data.Set, Data.Map, etc.

[GHC]

#633: add dataCast{1,2} to Data instances of Data.Set, Data.Map, etc.
-----------------------------+----------------------------------------------
 Reporter:  jrussell         |          Owner:         
     Type:  feature request  |         Status:  new    
 Priority:  normal           |      Milestone:         
Component:  libraries/base   |        Version:  6.4.1  
 Severity:  normal           |       Keywords:         
       Os:  Unknown          |   Architecture:  Unknown
-----------------------------+----------------------------------------------
Adding

 {{{dataCast1 = gcast1}}}

 to the Data instances of {{{Data.Set}}} and {{{Data.IntMap}}} and

 {{{dataCast2 = gcast2}}}

 to the Data instance of {{{Data.Map}}}
 would be handy.

 I can't see any reason not to; it doesn't break the abstraction
 and it allows Set and Map to be used with SYB functions like ext1Q
 and friends.

 There are probably other data types that could benefit from
 this too.

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/633>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler