patch applied (ghc): Teach SpecConstr how to handle mutually-recursive functions

Wed Nov 29 13:39:31 PST 2006  [email protected]
  * Teach SpecConstr how to handle mutually-recursive functions
  
  Roman found cases where it was important to do SpecConstr for
  mutually-recursive definitions.  Here is one:
  	foo :: Maybe Int -> Int
  	foo Nothing  = 0
  	foo (Just 0) = foo Nothing
  	foo (Just n) = foo (Just (n-1))
  By the time SpecConstr gets to it, it looks like this:
  	lvl = foo Nothing
  	foo Nothing  = 0
  	foo (Just 0) = lvl
  	foo (Just n) = foo (Just (n-1))
  
  Happily, it turns out to be rather straightforward to generalise the
  transformation to mutually-recursive functions.  Look, ma, only 4 
  extra lines of ocde!
  
  
  

    M ./compiler/specialise/SpecConstr.lhs -72 +76