patch applied (ghc): Small improvement to CorePrep

[Simon Peyton Jones]

Mon Dec 20 04:37:15 PST 2010  simonpj at microsoft.com
  * Small improvement to CorePrep
  
  This change avoids unnecessary bindings. Example
  
       foo (let fn = \x.blah in
            in fn)
  
  We were generating something stupid like
  
      let fn = \x.blah in
      let fn' = \eta. fn eta
      in foo fn
  
  Now we don't.  The change is quite small.
  
  Thanks to Ben for showing me an example of this happening.

    M ./compiler/coreSyn/CorePrep.lhs -6 +6

View patch online:
http://darcs.haskell.org/cgi-bin/darcsweb.cgi?r=ghc;a=darcs_commitdiff;h=20101220123715-1287e-6f7f8844054d1ff8e48fb5824b8721afeee2e68e.gz