The "assignment from a lazy list" section of RFC 123 suggests a system
for requesting the first however many items out of a map or grep by
making it lazy and then assigning it to an array of that size.
"last" is more flexible, if you are looking for a condition more
complex than the first one, say you want all the temperature on all
the days preceding the day the all-time record was broken, you can do
that with "last" if you have the old record, otherwise you need to
iterate over and refuse the rest of the records.
Using a function-based lazy list
@days_up_to_recordbreaker = () = lazy {
my $day;
while($day++){
(yield $high[$day]) > $AllTimeRecord and return ();
}
}
Using grep without last
my $unbroken = 1;
@days_up_to_recordbreaker = @high [
grep {
$unbroken &&= $high[$_] <= $AllTimeRecord
} (0..$#high)
]
Using for/push
for @high {
push @days_up_to_recordbreaker, $_;
last if $high[$_] > $AllTimeRecord;
}
Using map/last
@days_up_to_recordbreaker = map{
$_ > $AllTimeRecord
?
$_ , last # is this right?
:
$_
} @high
I wrote a map w/o last but erased it for brevity :)
--
David Nicol 816.235.1187 [EMAIL PROTECTED]
perl -e'map{sleep print$w[rand@w]}@w=<>' /usr/dict/words
