14 Jul
2005
14 Jul
'05
6:51 a.m.
On Thu, Jul 14, 2005 at 01:44:05PM +0300, Yitzchak Gale wrote:
Here it is translated into regular monad syntax:
coinsM _ 0 k = return [] coinsM _ _ 0 = [] coinsM cs a k = do t <- init (tails cs) let h = head t unless (h <= a) [] s <- coinsM t (a-h) (k-1) return (h:s)
(The function "unless" is from the Control.Monad module.)
[] is an instance of MonadPlus, which allows you to use "guard" instead of "unless ...": guard (h <= a) Best regards Tomasz