[GHC] #9231: 7.8 regression in Read instance of Data.Fixed.Pico

[GHC]

#9231: 7.8 regression in Read instance of Data.Fixed.Pico
-------------------------------------+------------------------------------
        Reporter:  leonbaum2         |            Owner:
            Type:  bug               |           Status:  new
        Priority:  normal            |        Milestone:
       Component:  libraries/base    |          Version:  7.8.2
      Resolution:                    |         Keywords:
Operating System:  Unknown/Multiple  |     Architecture:  Unknown/Multiple
 Type of failure:  None/Unknown      |       Difficulty:  Unknown
       Test Case:                    |       Blocked By:
        Blocking:                    |  Related Tickets:
-------------------------------------+------------------------------------

Comment (by hvr):

 The parser code seems totally wrong, e.g. consider

 {{{#!hs
 convertFixed :: forall a . HasResolution a => Lexeme -> ReadPrec (Fixed a)
 convertFixed (Number n)
  | Just (i, f) <- numberToFixed r n =
     return (fromInteger i + (fromInteger f / (10 ^ r)))
     where r = resolution (undefined :: Fixed a)
 convertFixed _ = pfail
 }}}

 And note that `resolution` doesn't return an exponent but rather a power
 of 10.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9231#comment:1>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler