Perl 6 - Starting with the basics - Case Study: Data Structure Selection(Random Numbers, pick)

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 11(Case Study: Data Structure Selection)の Random Numbers、Exercise: 5.を取り組んでみる。

Exercise: 5.

コード(Emacs)

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

sub histogram($string) {
    my %histo;
    for $string.comb -> $letter {
        %histo{$letter}++;
    }
    return %histo;
}

sub choose_from_hist(%histogram) {
    my $letter = %histogram.keys.pick;

    return $letter, %histogram{$letter} / [+] %histogram.values;
}

say choose_from_hist(histogram("We all live in a yellow submarine"));
for 1..10 {
    say choose_from_hist(histogram("aab"));
}

入出力結果(Terminal, REPL)

$ ./sample5.pl
(b 0.030303)
(a 0.666667)
(a 0.666667)
(b 0.333333)
(b 0.333333)
(a 0.666667)
(a 0.666667)
(b 0.333333)
(b 0.333333)
(b 0.333333)
(a 0.666667)
$