dyckword (hackage): The binary Dyck language consists of all strings of evenly balanced left and right parentheses, brackets, or some other symbols, together with the empty word. Words in this language are known as Dyck words, some examples of which are ()()(), (())((())), and ((()()))().  The counting sequence associated with the Dyck language is the Catalan numbers, who describe properties of a great number of combinatorial objects.
Keywords: bsd3|library|math|formal-languages|haskell|parentheses