On Tuesday 14 August 2007 10:17:53 Dougal Stanton wrote:
I'm looking for cool but mind-bending examples of functional brilliance.
Let us say, hypothetically, you had a bathroom without any reading material. And having read all the Dilbert and Garfield you could seriously stomach, decide you should educate yourself while "on the job". :-)
So you decide to print up some "one-liner" style programs into a little booklet. Something between credit-card and postcard sized, with a neat but mind-bending program on it. Don Stewart occasionally swoops in with some fixpoint malarkey to defuse heated discussions. I mean that kind of thing, but with a slightly wider scope than just fibs...
Suggestions, please!
D.
Here's a small puzzle: without using a Haskell interpreter, explain what the 'foo' function does.
foo = filterM (const [True, False])
In case you aren't familiar, here's the definition of filterM:
filterM :: (Monad m) => (a -> m Bool) -> [a] -> m [a] filterM _ [] = return [] filterM p (x:xs) = do flg <- p x ys <- filterM p xs return (if flg then x:ys else ys)
Cheers, Spencer Janssen