#!/usr/bin/perl

use strict;
use warnings;
use feature 'say';

use List::Util ();
use List::Gen qw(:modify :filter);

use Benchmark 'cmpthese';

for my $first (0, 1) {
    my $list = [$first, (1) x (1_000_000)];
    say "first: $first";
    cmpthese(0, {
            lu => sub {all_lu($list)},
            for => sub {all_for($list)},
            lg => sub {all_gen($list)},
        });
    say '';
};

say "chaining:";
my @list = (1 .. 10_000);
# Lookahead (default) would generate one more value
local $List::Gen::LOOKAHEAD = 0;

cmpthese(0, {
        mgm => sub {
            (map {$_->[0]} grep {!($_->[1] % 10)} map {[$_, tf($_)]} @list)[0]
        },
        gfg => sub {
            (gen {$_->[0]} filter {!($_->[1] % 10)} gen {[$_, tf($_)]} \@list)->[0]
        },
    });

# artificially "heavy" transformation.
sub tf {
    select(undef, undef, undef, 0.000001);
    $_[0] + 1;
}

# short-circuit "all"
sub all_lu {
    List::Util::all {$_} @{shift()};
}

# short-circuit for-loop
sub all_for {
    for (@{shift()}) {
        return 0 unless $_;
    }
    1;
}

# short-circuit lazy generator
sub all_gen {
    !List::Gen(shift)->do(sub {&last(1) unless $_});
}

__DATA__
first: 0
          Rate       lu       lg      for
lu       396/s       --     -99%    -100%
lg     27574/s    6869%       --    -100%
for 10156692/s 2567064%   36734%       --

first: 1
      Rate    lg   for    lu
lg  4.62/s    --  -90%  -93%
for 48.5/s  949%    --  -31%
lu  70.6/s 1427%   46%    --

chaining:
      Rate    mgm    gfg
mgm 12.5/s     --  -100%
gfg 3790/s 30320%     --