順列 perl

nise_permutate.pl

#!/usr/bin/perl

use strict;
use warnings;

my $main = sub {
  my $h = shift;
  print $h."\n";
};

my @ascii = qw/2 1/;
my $length = 4;

nise_permutate(\@ascii, $main, $length);

sub nise_permutate {
  my ($set, $subref, $length) = @_; 
  my $nestfor = sub { nestfor($set, $_[0], $_[1]); };
  if ($length != 0) { $subref = gen($subref) for 1..$length; }
  $nestfor->($subref, '');
}

sub gen {
  my $s = shift;
  return sub {nestfor(\@ascii,$s,shift)};
}

sub nestfor {
  my $ary = shift;
  my $sub = shift;
  my $bind = shift || ''; 
  $sub->("$bind$_") for @$ary;
}

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