On Mar 8, 2006, at 1:29 PM, zell_ffhut wrote:
Im afraid im baffled again!
Im now trying to add a char to a string of strings (eg - ["434233434" "444929192" "909313434"]
Im sure i can use my previous function to help me achive this, but i can't seem to get it workinging
charToGrid :: Char -> Position -> Grid -> Grid charToGrid c (row,col) g = concat g (changeValue c(row*9 + col))
Im not sure i should be using concat, as i have to return a grid as it was given, just with the added char.
As before, the idea is to create a new list with the changes you want, only now you have a list "two levels deep". So the first thing to do is to pick out the sublist (row) you want to "change" and create a new changed sublist (row), and then rebuild your grid. Try this, it may get you started: updateList :: (a -> a) -> Int -> [a] -> [a] updateList f i l = begin ++ (f x : end) where (begin, x : end) = splitAt i l BTW, lists aren't very good for these kinds of manipulations. If you really need an indexable, mutable data structure, try one of Data.Array.* Rob Dockins Speak softly and drive a Sherman tank. Laugh hard; it's a long way to the bank. -- TMBG