ghc5.04.1 deriving Read/Show broken

[George Russell]

Simon Marlow wrote:
[snip]
> It turns out there's a bug in the Read instance for Maybe.  It's rather
> unfortunate that there's no workaround other than defining your own
> Maybe type.
> 
> The bug was also in 5.04.
[snipped]
No it wasn't.  This is what happens with ghc5.04 on Linux
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# ghci --interactive
   ___         ___ _
  / _ \ /\  /\/ __(_)
 / /_\// /_/ / /  | |      GHC Interactive, version 5.04, for Haskell 98.
/ /_\\/ __  / /___| |      http://www.haskell.org/ghc/
\____/\/ /_/\____/|_|      Type :? for help.

Loading package base ... linking ... done.
Loading package haskell98 ... linking ... done.
Prelude> :load GHCBug
Compiling GHCBug           ( GHCBug.hs, interpreted )
Ok, modules loaded: GHCBug.
*GHCBug> show (read (show (Commit 1 "1" Nothing)) :: Command)
"Commit 1 \"1\" Nothing"
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> You should have reported it earlier, George
> :-)  
Ah well, if only I had had a pre-release snapshot I could have tried it out on.
Such is life.