avoid array creation in matchAt

src/Sapl/FastString.icl

@@ -58,7 +58,10 @@ matchAt :: !String !String !Int -> Bool
 matchAt s1 s2 p 
 	| ((size s1) + p) > (size s2) 
 				= False
-				= and [s1.[i] == s2.[p + i] \\ i <- [0..((size s1) - 1)]]
+				= eqS ((size s1) - 1)
+where
+	eqS 0 = s1.[0] == s2.[p + 0]
+	eqS i = s1.[i] == s2.[p + i] && eqS (i - 1) 
 
 countCharBackwards :: !Char !String -> Int
 countCharBackwards chr str