Checking if a string consists of balanced parenthesis

Question

I wrote the following program to check strings for balanced parenthesis:

isBalanced xs = isBalanced\' xs []

isBalanced\' [] [] = True
isBalanced\' [] _  = False         


        

Answer 1

Probably overkill for a problem this simple, but you could try looking up parser combinators.

As a more elementary simplification, you could rewrite your recursion into folding over a function that takes a stack and a character from the string to a new stack. (Whether this would make actually it simpler is in the eye of the beholder, though).