[Haskell-cafe] least fixed points above something
Jens Blanck
jens.blanck at gmail.com
Thu Mar 19 05:49:18 EDT 2009
Hi,
I found myself writing the following
leastFixedPoint :: (Eq a) => (a -> a) -> a -> a
leastFixedPoint f x = fst . head . dropWhile (uncurry (/=)) $ zip l (tail l)
where l = iterate f x
and was a bit surprised that I couldn't get any matches on hoogle for the
type above. The closest one is fix :: (a -> a) -> a but that sort of assumes
that we're starting the fixed point search from the bottom element
(undefined).
Anyway, is there a nicer way of doing the above?
Jens
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