Sha256: 9e6d526443f08b38f88ccdaf6cda09d1cdc46d7a5b8a41c9fe199810cb1f784a
Contents?: true
Size: 928 Bytes
Versions: 254
Compression:
Stored size: 928 Bytes
Contents
module Brackets (arePaired) where
data BracketType = Opening | Closing
data Stack a = Empty | Elem a (Stack a)
push :: Char -> Stack Char -> Stack Char
push = Elem
pop :: Stack Char -> Stack Char
pop Empty = Empty
pop (Elem _ stack) = stack
arePaired :: String -> Bool
arePaired xs = checkBalance xs Empty
checkBalance :: String -> Stack Char -> Bool
checkBalance [] Empty = True
checkBalance [] _ = False
checkBalance (x:xs) stack =
case classify x of
Just Opening -> checkBalance xs $ push x stack
Just Closing -> (x `closes` stack) && checkBalance xs (pop stack)
_ -> checkBalance xs stack
classify :: Char -> Maybe BracketType
classify x
| x `elem` "([{" = Just Opening
| x `elem` ")]}" = Just Closing
| otherwise = Nothing
closes :: Char -> Stack Char -> Bool
closes _ Empty = False
closes x (Elem y _) =
x == ')' && y == '('
|| x == ']' && y == '['
|| x == '}' && y == '{'
Version data entries
254 entries across 254 versions & 1 rubygems