Perl 6 - Starting with the basics - Strings(String traversal with a for loop, while loop, substr, chars(length))

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)の String traversal with a for loop の Exercise.を取り組んでみる。

String traversal with a for loop の Exercise.

コード(Emacs)

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

say '1.';

sub backward($letters) {
    my $index = $letters.chars;    
    while $index > 0 {
        $index--;
        my $letter = substr $letters, $index, 1;
        say $letter;
    }
}

my $fruit = "banana";

backward($fruit);


my $suffix = 'ack';

for 'J'..'Q' {
    if ($_ eq 'O' or $_ eq 'Q') {
        say $_ ~ 'u' ~ $suffix;
    } else {
        say $_ ~ $suffix;
    }
}

入出力結果(Terminal, REPL)

$ ./sample_for.pl 
1.
a
n
a
n
a
b
Jack
Kack
Lack
Mack
Nack
Ouack
Pack
Quack
$