On Nov 2, 2010, at 21:10, Daniel Fischer wrote:
On Saturday 30 October 2010 16:59:00, Jonathan Phillips wrote:
I have a list (more precisely a string) which I'm trying to recurse through, editing sections as I come to it. It's obvious how to do it with a for loop, but I'm doing it all wrong in haskell, as this simple task is running mind-numbingly slowly.
Maybe you should split the string into lines using 'lines' from Data.List, then divide each line into 23-4-rest chars somehow using 'splitAt', apply the "show ((read str :: Integer) + 1)" part, justify the answer, probably by appending four spaces and then taking the first four characters, put the 23-changed4-rest parts back together with ++, and finally join all the lines again with 'unlines'.
l | l < 4 -> s ++ " " ++ addOneNum' xs (n+4) -- guessing it's the same number of spaces for those
I suppose it shall justify the number to length 4. I.e.
changeNo v (w:x:y:z:xs) n = case length(s@(show((read([w,x,y,z])::Integer) + 1))) of 0 -> addOneNum (v ++ " ") xs (n+4) 1 -> addOneNum (v ++ s ++ " ") xs (n+4) 2 -> addOneNum (v ++ s ++ " ") xs (n+4) 3 -> addOneNum (v ++ s ++ " ") xs (n+4) 4 -> addOneNum (v ++ s) xs (n+4) _ -> error "asdf"
Cheers, Bastian