module Main
total
strReplace : String -> String -> String -> String
strReplace needle replacement = go "" Z (unpack needle) . unpack
where
go : String -> Nat -> List Char -> List Char -> String
go acc _ [] text = acc ++ pack text
go acc _ _ [] = acc
go acc (S k) needle (x::xs) = go acc k needle xs
go acc _ (n::ns) (x::xs) =
if isPrefixOf (n::ns) (x::xs)
then go (acc ++ replacement) (length ns) (n::ns) xs
else go (acc ++ cast x) Z (n::ns) xs
main : IO ()
main = putStrLn $ strReplace "foo" "bar" "foo"
