むりやりperlで関数型言語っぽくappend書いてみた

append.pl

#!/usr/bin/env perl
use strict;
use warnings;

my $append; $append = sub {
    my ($X, $Y) = @_;
    if (0 == scalar @$X) {
        return $Y;
    }
    else {
        my $A = shift @$X;
        my $Z = $append->($X, $Y);
        unshift @$Z, $A;
        return $Z;
    }
};

print join " ", @{$append->([1,2,3],[4,5,6])};