progress on challenge 2

cw/src/Challenges.hs

@@ -161,16 +161,26 @@ insertString :: RandGrid -> String -> StdGen -> (RandGrid,StdGen)
 insertString rg s gen | elemAt rg (x,y) /= Rand &&
                         elemAt rg (x,y) /= Letter (head s) = insertString rg s newGen        --guard:if position is invalid, generate new position
                       | length vDirs == 0                  = insertString rg s newGen        --guard:if no valid orientations exist, generate new position
-                      | otherwise                           
+                      | otherwise                          = 
     where
       ((x,y),newGen) = generatePos gen (length rg)
       vDirs = validDirs rg s (x,y)
 
-      addToGrid :: String -> Orientation -> RandGrid
-      addToGrid s dir = iterate 
-      --iterate to get positions
-      --zip together with string
-      --map to add to grid
+      addToGrid :: Orientation -> String -> (Int,Int) -> RandGrid
+      addToGrid dir (c:cs) (x',y') = addToGrid dir cs (nextPos dir (x',y')) charAdded
+          where
+            charAdded = insertAt2D (Letter c) (x',y') rg
+      --addToGrid dir = map (\(c,(m,n)) -> insertAt2D (Letter c) (m,n) rg) (zip s (take (length s) $ iterate (nextPos dir) (x,y)))
+
+
+--inserts element at location in 2d array
+insertAt2D :: a -> (Int,Int) -> [[a]] -> [[a]]
+insertAt2D newElement (x,y) grid = insertAt a x (grid !! y)
+
+--using code from https://stackoverflow.com/questions/43291442/haskell-insert-an-element-on-nth-position
+insertAt :: a -> Int -> [a] -> [a]
+insertAt newElement 0 as = newElement:as
+insertAt newElement i (a:as) = a : insertAt newElement (i - 1) as
 
 
 generatePos :: StdGen -> Int -> ((Int,Int),StdGen)