Hi,
On Sun, Jul 5, 2009 at 3:44 PM, Daniel Fischer
Am Sonntag 05 Juli 2009 21:05:20 schrieb Patrick LeBoutillier:
Hi,
Thanks for the help. I figured it out after that. I'm having a hard time with the other exercises though, I'm currently stuck at 14:
class Misty m where banana :: (a -> m b) -> m a -> m b unicorn :: a -> m a
-- Exercise 14 -- Relative Difficulty: 6 moppy :: (Misty m) => [a] -> (a -> m b) -> m [b] moppy = error "todo"
moppy [] mop = ? moppy (a:as) mop = (mop a) ?? (moppy as mop)
use (among other things) banana and unicorn to replace the question marks
I came up with this:moppy [] mop = unicorn [] moppy (a:as) mop = banana (\b -> banana (\bs -> unicorn (b:bs)) (moppy as mop)) (mop a) moppy [] mop = unicorn [] moppy (a:as) mop = banana (\b -> banana (\bs -> unicorn (b:bs)) (moppy as mop)) (mop a) How do I make the second one nicer/shorter? Patrick
Does anyone know if the solutions are posted anywhere?
They're (under different names) in the standard libraries :)
I found it: forM
Patrick
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-- ===================== Patrick LeBoutillier Rosemère, Québec, Canada