patch applied (ghc): Float casts out of lambdas

[Simon Peyton Jones]

Mon Feb  5 09:35:44 PST 2007  simonpj at microsoft.com
  * Float casts out of lambdas
  
  See Note [Casts and lambdas] in SimplUtils.  I found this transformation
  when staring at some cast-heavy code generated by
  Language.Haskell.Lexer.hs in the haskell-src library.
  
  The basic transformation is this:
  	(\x. e `cast` g1)  -->  (\x.e) `cast` (tx -> g1)
  where x:tx.
  

    M ./compiler/simplCore/SimplUtils.lhs +23