Re^4: Generating lists of strings

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.

Comment on Re^4: Generating lists of strings Select or Download Code

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Re^5: Generating lists of strings by BrowserUk (Patriarch) on Jan 24, 2010 at 22:38 UTC
What does that have to do with anything? Everything! First: Had I found the NestedLoops() syntax intelligable, I might never have sought my own solution, but as is, I would never have come up with the right syntax to do what you've done. Second: The application I originally wrote nFor() for needed to be as efficient as possible: `c:\test>junk94 Took 0.557000 c:\test>nfor Took 0.09644` [download] Given the very essence of the problems these routines are designed to handle is deeply nested algorithms, that nearly 6x difference can become very significant. Plus, if I need to tweak the function for specific purposes, my code is infinitely simpler to modify than NestedLoops(). Read more... (2 kB) Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error. "Science is about questioning the status quo. Questioning authority". In the absence of evidence, opinion is indistinguishable from prejudice. "I'd rather go naked than blow up my ass"	[reply] [d/l] [select]
Re^6: Generating lists of strings by ikegami (Patriarch) on Jan 24, 2010 at 22:48 UTC
The application I originally wrote nFor() for needed to be as efficient as possible: So make a module. Don't suggest that the OP use and support that big chunk of complex code. and your my code is infinitely simpler to modify than NestedLoops(). Really? Unless each level of nesting is the same, `nFor` degrades to `nFor { print map $lists[$_][ $_[$_] ], 0..$#_; } map 0+@$_, @lists;` [download] I wrote that and I can't even read it.	[reply] [d/l] [select]
Re^7: Generating lists of strings by BrowserUk (Patriarch) on Jan 24, 2010 at 23:08 UTC
Don't suggest that the OP use and support that big chunk of complex code. What are you on about? If it works for him, then he has no need to "support it". If it doesn't quite work for him, he stands a far better chance of understanding and modifying Read more... (1110 Bytes) Than Read more... (3 kB) And far more chance of modifying code that is entirely within his own control. in a timely manner, than of making a persuasive enough case to have a remote author make application specific changes to a complex, generic routine. nFor degrades to `nFor { print map $lists[$_][ $_[$_] ], 0..$#_; } map 0+@$_, @lists;` I wrote that and I can't even read it. No, neither can I. Nor whatever obscure point you are trying to make by it. Why should it "degrade"? Unless as a result of your corrosive comments. I offered the OP a simple, correct, perlish solution to his question. As have others. It is his choice to use whichever he finds most suitable. Why the **** are you jumping up and down over my correct solution, whilst ignoring the incorrect ones? Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error. "Science is about questioning the status quo. Questioning authority". In the absence of evidence, opinion is indistinguishable from prejudice. "I'd rather go naked than blow up my ass"	[reply] [d/l] [select]
Re^8: Generating lists of strings by ikegami (Patriarch) on Jan 24, 2010 at 23:21 UTC
Re^9: Generating lists of strings by BrowserUk (Patriarch) on Jan 25, 2010 at 00:07 UTC
Some notes below your chosen depth have not been shown here
Re^5: Generating lists of strings by BrowserUk (Patriarch) on Jan 25, 2010 at 01:16 UTC
For the record, the above modified-out-of-all-recognition post originally contained following which is entirely different in both content and tone: What does that have to do with anything? `#! 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]	[reply] [d/l]
Re^5: Generating lists of strings by BrowserUk (Patriarch) on Jan 25, 2010 at 00:56 UTC
nFor would require: `local $, = ", "; local $\ = "\n"; nFor { print map $lists[$_][ $_[$_] ], 0..$#_; } map 0+@$_, @lists;` [download] Baloney! You just like complicated don't you. All that's needed is the intuative: `my @list1 = qw( apple orange tomato ); my @list2 = qw( dog cat platypus ); my @list3 = qw( 1 2 III ); nFor{ print join ' ', $list1[ $_[0] ], $list2[ $_[1] ], $list3[ $_[2] ], } ( 3 ) x 3;` [download] Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error. "Science is about questioning the status quo. Questioning authority". In the absence of evidence, opinion is indistinguishable from prejudice. "I'd rather go naked than blow up my ass"	[reply] [d/l] [select]
Re^6: Generating lists of strings by ikegami (Patriarch) on Jan 25, 2010 at 02:54 UTC
You assume they all have the same number of elements.	[reply]
Re^7: Generating lists of strings by BrowserUk (Patriarch) on Jan 25, 2010 at 03:07 UTC
Yup! The OPs problem description. How about you try and find one SoPW here calling for the iteration of a varible length list of variable length lists? Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error. "Science is about questioning the status quo. Questioning authority". In the absence of evidence, opinion is indistinguishable from prejudice. "I'd rather go naked than blow up my ass"	[reply]
Re^8: Generating lists of strings by ikegami (Patriarch) on Jan 25, 2010 at 03:11 UTC