I much prefer the far simpler syntax of nFor.

And nothing's stopping you from providing that interface. 

#! perl -slw
use strict;

use Algorithm::Loops qw( NestedLoops );

sub nFor(&@) {
    my $cb = shift;
    NestedLoops([ map [ 0..$_-1 ], @_ ], $cb);
}

my @digits = 1 .. 3;

nFor {
    print join '', @digits[ @_ ];
} ( 3 ) x 4;

[download]

than the tortuous documentation for NestedLoops which I've still never wrapped by brain around.

Say you want 

apple, dog, 1
apple, dog, 2
apple, dog, III
apple, cat, 1
apple, cat, 2
apple, cat, III
apple, platypus, 1
apple, platypus, 2
apple, platypus, III
orange, dog, 1
orange, dog, 2
orange, dog, III
orange, cat, 1
orange, cat, 2
orange, cat, III
orange, platypus, 1
orange, platypus, 2
orange, platypus, III
tomato, dog, 1
tomato, dog, 2
tomato, dog, III
tomato, cat, 1
tomato, cat, 2
tomato, cat, III
tomato, platypus, 1
tomato, platypus, 2
tomato, platypus, III

[download]
from 
# Variable number of lists of variable length
my @lists = (
   [qw( apple orange tomato )],
   [qw( dog cat platypus )],
   [qw( 1 2 III )],
);

[download]

That's what NestedLoops is for: 

local $, = ", ";
local $\ = "\n";
NestedLoops(\@lists, sub { print @_ });

[download]

nFor would require: 

local $, = ", ";
local $\ = "\n";
nFor { print map $lists[$_][ $_[$_] ], 0..$#_; } map 0+@$_, @lists;

[download]

Maybe you wouldn't have a problem understanding NestedLoops if it provided a map-ish interface? 

sub nested(&@) {
    my $cb = shift;
    NestedLoops(\@_, $cb);
}

local $, = ", ";
local $\ = "\n";
nested { print @_; } @lists;

[download]

Update: Switched initial line to something less rude.

In reply to Re^4: Generating lists of strings by ikegami
in thread Generating lists of strings by Anonymous Monk

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.