Perl 6 - Starting with the basics - Strings(String Traversal with a while or for Loop, substr, chars, index)

Think Perl 6

開発環境

• macOS Sierra - Apple (OS)
• Emacs (Text Editor)
• Perl 6 (プログラミング言語)
• Rakudo(コンパイラ、実装)

Think Perl 6: How to Think Like a Computer Scientist (Laurent Rosenfeld(著)、Allen B. Downey(著)、Oreilly & Associates Inc)のPart 1(Starting with the basics)、Chapter 7(Strings)、String Traversal with a while or for Loop の Exercise: String Traversal.を取り組んでみる。

Exercise: String Traversal.

コード(Emacs)

#!/usr/bin/env perl6
# -*- coding: utf-8 -*-

sub backward($word) {
    say 'backward';
    my $index = $word.chars;

    while $index > 0 {
        my $letter = substr $word, $index - 1, 1;
        say $letter;
        $index--;
    }
}

backward '';
backward 'a';
backward 'banana';
backward '日本語';

入出力結果(Terminal, REPL)

$ ./sample_traversal.pl
backward
backward
a
backward
a
n
a
n
a
b
backward
語
本
日
$