Fix POD, fix bug in 3rd example

best-of-rosettacode/balanced-brackets.pl

@@ -1,6 +1,8 @@
+use v6;
+
 =begin pod
 
-=head1 Problem
+=head1 Balanced brackets
 
 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.
@@ -10,17 +12,19 @@ =head1 More
 L<http://rosettacode.org/wiki/Balanced_brackets#Perl_6>
 
 =head1 What's interesting here?
-* idiomatic solutions
-* hyper operators
-* switch statement
-* roll
-* grammar
+
+=item idiomatic solutions
+=item hyper operators
+=item switch statement
+=item roll
+=item grammar
 
 =head2 Depth counter
 
 =end pod
 
-sub balanced($s) {
+{
+  sub balanced($s) {
     my $l = 0;
     for $s.comb {
         when "]" {
@@ -32,65 +36,74 @@ ($s)
         }
     }
     return $l == 0;
-}
+  }
 
-my $n = prompt "Number of brackets";
-my $s = (<[ ]> xx $n).pick(*).join;
-say "$s {balanced($s) ?? "is" !! "is not"} well-balanced"
+  my $n = prompt "Number of brackets >";
+  my $s = (<[ ]> xx $n).pick(*).join;
+  say "$s {balanced($s) ?? "is" !! "is not"} well-balanced";
+}
 
 =begin pod
 
 =head2 FP oriented
 
 =end pod
 
-sub balanced($s) {
+{
+  sub balanced($s) {
     .none < 0 and .[*-1] == 0
-        given [\+] '\\' «leg« $s.comb;
-}
+      given [\+] '\\' «leg« $s.comb;
+  }
 
-my $n = prompt "Number of bracket pairs: ";
-my $s = <[ ]>.roll($n*2).join;
-say "$s { balanced($s) ?? "is" !! "is not" } well-balanced"
+  my $n = prompt "Number of bracket pairs: ";
+  my $s = <[ ]>.roll($n*2).join;
+  say "$s { balanced($s) ?? "is" !! "is not" } well-balanced";
+}
 
 =begin pod
 
 =head2 String munging
 
 =end pod
 
-sub balanced($_ is copy) {
-    () while s:g/'[]'//;
+{
+  sub balanced($_ is copy) {
+    s:g/'[]'// while m/'[]'/;
     $_ eq '';
-}
+  }
 
-my $n = prompt "Number of bracket pairs: ";
-my $s = <[ ]>.roll($n*2).join;
-say "$s is", ' not' xx not balanced($s)), " well-balanced";
+  my $n = prompt "Number of bracket pairs: ";
+  my $s = <[ ]>.roll($n*2).join;
+  say "$s is", ' not' xx not balanced($s), " well-balanced";
+}
 
 =begin pod
 
 =head2 Prasing with a grammar
 
 =end pod
 
-grammar BalBrack {
+{
+
+  grammar BalBrack {
     token TOP { ^ <balanced>* $ };
     token balanced { '[]' | '[' ~ ']' <balanced> }
+  }
+
+  my $n = prompt "Number of bracket pairs: ";
+  my $s = <[ ]>.roll($n*2).join;
+  say "$s { BalBrack.parse($s) ?? "is" !! "is not" } well-balanced";
+
 }
-
-my $n = prompt "Number of bracket pairs: ";
-my $s = <[ ]>.roll($n*2).join;
-say "$s { BalBrack.parse($s) ?? "is" !! "is not" } well-balanced";
 
 =begin pod
 
 =head1 Features used
 
-C<roll> - L<http://perlcabal.org/syn/S32/Containers.html#roll>
-C<given> - L<http://perlcabal.org/syn/S04.html#Switch_statements>
-C<prompt> - L<http://perlcabal.org/syn/S32/IO.html#prompt>
-C<grammar> - L<http://perlcabal.org/syn/S05.html#Grammars>
+=item C<roll> - L<http://perlcabal.org/syn/S32/Containers.html#roll>
+=item C<given> - L<http://perlcabal.org/syn/S04.html#Switch_statements>
+=item C<prompt> - L<http://perlcabal.org/syn/S32/IO.html#prompt>
+=item C<grammar> - L<http://perlcabal.org/syn/S05.html#Grammars>
 
 =end pod