Thanks guys for all your help, finally through code, sweat and tears i have found the solution;
isSubStrand:: String -> String -> Bool
isSubStrand [] [] = True
isSubStrand [] (y:ys) = False
isSubStrand (x:xs) [] = False
isSubStrand (x:xs) (y:ys)
| length(x:xs)>length(y:ys) = False
| take (length (x:xs)) (y:ys)==(x:xs) = True
| otherwise = isSubStrand (x:xs) ys
thanks again
Peter Stranney
Ketil Malde
You might also want to look at the earlier `any prefix of tails' suggestion, as it makes the solution a rather simple one-liner.
Wouldn't that be looking for a sub*string*, and not a (general) sub*sequence* (which I think does not have to be contigous?) -kzm -- If I haven't seen further, it is by standing in the footprints of giants Peter Stranney --------------------------------- Do you Yahoo!? Yahoo! Mail - You care about security. So do we.