Re: [Haskell-cafe] least fixed points above something

I always feel that the compiler should do such optimizations for me :) On 19 Mar 2009, at 16:21, Neil Mitchell wrote:

...

I've used a similar function myself, but why write it in such a complicated way? How about

lfp :: Eq a => (a -> a) -> a -> a lfp f x | f x == x = x | otherwise = lfp f (f x)

I've used a similar function too, but your version computes f x twice per iteration, I wrote mine as:

fix :: Eq a => (a -> a) -> a -> a fix f x = if x == x2 then x else fix f x2 where x2 = f x

I find this fix much more useful than the standard fix.

Thanks

Neil