Author: Filip Sergot

Generate a string with N opening brackets (“[”) and N closing brackets (“]”), in some arbitrary order.

Determine whether the generated string is balanced; that is, whether it consists entirely of pairs of opening/closing brackets (in that order), none of which mis-nest.

More

http://rosettacode.org/wiki/Balanced_brackets#Raku

What's interesting here?

• idiomatic solutions

• hyper operators

• switch statement

• roll

• grammar

Features used

• roll - https://doc.perl6.org/routine/roll#class_List

• given - https://doc.perl6.org/syntax/given#language_documentation_Control_Flow

• prompt - https://doc.perl6.org/routine/prompt

• grammar - https://doc.perl6.org/language/grammars

Depth counter

FP oriented

String munging

Parsing with a grammar

Source code: balanced-brackets.pl

use v6;

{

    grammar BalBrack {
        token TOP { ^ <balanced>* $ };
        token balanced { '[]' | '[' ~ ']' <balanced> }
    }

    my $s = <[ ]>.roll($n*2).join;
    say "Parsing brackets with a grammer";
    say "$s { BalBrack.parse($s) ?? "is" !! "is not" } well-balanced";

}