Comments on: Cute Haskell Code

By: Morten

Morten — Sun, 01 Feb 2009 19:19:39 +0000

Sorry, I forgot the i import Monad cipherText = "LUXDZNUAMNDODJUDTUZDGYQDLUXDGOJDCKDTKKJDOZ" i = 20 main = print (sequence $ cipherText >>= (\x -> [foldM (\y a -> lookup y (zip ('Z':['A'..'Y']) ['A'..'Z'])) x [1..i]]))

By: Morten

Morten — Sun, 01 Feb 2009 17:21:10 +0000

cipherText = "LUXDZNUAMNDODJUDTUZDGYQDLUXDGOJDCKDTKKJDOZ" main = print (sequence $ cipherText >>= (\x -> [lookup x (zip ('Z':['A'..'Y']) ['A'..'Z'])])) This solution uses monad bindings.

By: batterseapower

batterseapower — Sun, 13 May 2007 19:57:02 +0000

Ah, that’s very nice indeed . And yeah, about the compile error: mea culpa. In my code that was “undefined”, but I felt I should add some error handling to clean it up for the post .

By: Peter

Peter — Sun, 13 May 2007 14:42:13 +0000

I had to add a $ after error to get your program to compile. Now, here's my attempt at being cute: shift i x = (dropWhile (/=x) $ ['A'..'Z']++['A'..'Z']) !! i This gives the error "index too large" from (!!) when x is not in ['A'..'Z'] or i is not in the proper range. (You'd want to check the arguments more carefully in a real program.)

By: batterseapower

batterseapower — Sun, 13 May 2007 14:24:01 +0000

Mmm, that’s a nice solution too. Though what I particularly liked about the ['A'..'Z'] style is that it never at any point did the ASCII conversion: it was just a literal encoding of how a human would think about the problem.

By: Vineet Kumar

Vineet Kumar — Sun, 13 May 2007 08:47:20 +0000

Maybe more readable?

> import Char
> shift i x = chr $ constrain $ ord x + i
> where constrain n =
> let a = ord ‘A’ in
> (n – a) `mod` 26 + a

Maybe not…