I've determined that the issue is the +@partials. Sometimes that is returning 1
as the length of the list instead of the full list. It looks to be whenever the
first index set returns the empty set, the size calculation fails.
________________________________
From: perl6 via RT <perl6-bugs-follo...@perl.org>
Sent: Wednesday, November 23, 2016 5:15 PM
To: tim.boll...@live.com
Subject: [perl #130160] AutoReply: [BUG] Flattened list iteration
Greetings,
This message has been automatically generated in response to the
creation of a trouble ticket regarding:
"[BUG] Flattened list iteration",
a summary of which appears below.
There is no need to reply to this message right now. Your ticket has been
assigned an ID of [perl #130160].
Please include the string:
[perl #130160]
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Thank you,
perl6-bugs-follo...@perl.org
-------------------------------------------------------------------------
It appears that when iterating lazily through a list that's been flattened (the
first time), sometimes certain elements are not reached. For background I was
writing some code that used a trie, and was attempting to find the word
"inclusive" out of input trigrams. I have cleared away as much of the
surrounding code as I could to provide a minimal test case. If you enable the
commented line (or otherwise iterate through the @partials list at least once
first), the output will be correct.
Thanks,
Tim Bollman
use v6;
sub find-words(@partials) {
state $output = '';
# my @a = @partials.kv;
for @partials.kv -> $i, $word {
my $backup = $output;
$output ~= $word;
take $output;
find-words(@partials[0 ..^ $i, $i ^..^ +@partials].flat());
$output = $backup;
}
}
my @found = gather find-words(<ive lus inc>);
.say for @found;
# ive
# ivelus
# lus
# lusive
# lusiveinc
# lusinc
# lusincive
# inc
# incive
