[Haskell] factoring `if'

[Colin Runciman]

Serge,

>How do you think, is the program (1) equivalent to (2) 
>in the meaning of Haskell-98 ?
>
>(1)   (\ x -> (if p x then  foo (g x)  else  foo (h x))
>              where
>              p ... g ... h ... foo ...
>      )
>
>(2)   (\ x -> foo  ((if p x then  g x  else  h x)
>                    where
>                    p ... g ... h ... foo ...
>                   )
>      )
>  
>
Both examples are illegal -- there are no where-expressions in Haskell, 
only where-equations. 

Ignoring the local definition part, however, the answer is no.  Lifting 
foo out of the branches of the conditional is only valid if foo is strict.

Colin R