[GHC] #2133: Add an instance for IArray (IOToDiffArray IOUArray) Bool

[GHC]

#2133: Add an instance for IArray (IOToDiffArray IOUArray) Bool
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    Reporter:  Deewiant  |       Owner:                   
        Type:  proposal  |      Status:  new              
    Priority:  normal    |   Component:  libraries (other)
     Version:  6.8.2     |    Severity:  normal           
    Keywords:            |    Testcase:                   
Architecture:  Unknown   |          Os:  Unknown          
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 An instance for `IArray (IOToDiffArray IOUArray) Bool` is missing from
 Data.Array.Diff. There doesn't seem to be any good reason for this: all
 the other `IArray UArray a` instances defined in Data.Array.IArray have
 corresponding instances. `Bool` is the sole exception.

 They cannot be added in user code without copying the entire
 Data.Array.Diff source, since the instances require internal functions
 which aren't exposed.

 Since all the instances are defined in exactly the same way, only varying
 the second type parameter, this requires practically zero work: just copy
 any of the other instances and replace the type parameter with `Bool`. A
 `Show` instance should also be provided. Both are in the patch.

 To be sure that the instances haven't been omitted because they don't
 work, I wrote a few QuickCheck properties (attached) and it seems that it
 does work without any trouble.

 Suggested deadline for discussion: 17th March 2008.

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/2133>
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