On 6/18/22 22:16, Bruce Gray wrote:
On Jun 18, 2022, at 10:42 PM, ToddAndMargo via perl6-users
wrote:
On 6/16/22 10:10, Rick Bychowski wrote:
sub MAIN($n = 20) {
.say for factors($n); # Nil
}
I thought `MAIN` was a reserved variable. Am
I missing something?
MAIN has a special
> On Jun 18, 2022, at 10:42 PM, ToddAndMargo via perl6-users
> wrote:
>
> On 6/16/22 10:10, Rick Bychowski wrote:
>> sub MAIN($n = 20) {
>>.say for factors($n); # Nil
>> }
>
>
> I thought `MAIN` was a reserved variable. Am
> I missing something?
MAIN has a special meaning as a sub
On 6/16/22 10:10, Rick Bychowski wrote:
sub MAIN($n = 20) {
.say for factors($n); # Nil
}
I thought `MAIN` was a reserved variable. Am
I missing something?
Clever!
I had missed checking "is-prime" straight away! Checked some large
primes, and my function hung badly. Thank you!
Is grep running on all "2 ..^ $n/2" values, and then picking the first,
or is that somehow lazily evaluated? I assume the former, or you'd have
no need to halve $n. But
Here's my new go to prime-factors function :
sub prime-factors( Int $n is copy where * > 1 ) {
gather {
while ( $n > 1 ) {
if ( $n.is-prime ) {
take $n;
last;
}
my $f = (2..^$n/2).grep($n %% *).first(*.is-prime);
This is because if there isn't an explicit return the last statement
evaluated is the implied return value.
So the last call (which returns Nil) was your implicit return.
Generally I try and avoid an implicit return if a function has more than a
couple of lines.
On Thu, 16 Jun 2022, 21:41 Rick
For example here:
https://github.com/manwar/perlweeklychallenge-club/blob/master/challenge-168/rick-bychowski/raku/ch-2.raku
I called the recursive function at various points in an if/else
statement, but each call was always the very last statement of the
branch/routine. Otherwise, even a
Yep, the "return factors($q, @f)" fixes it. I've not called a recursion
from anywhere other than the end of a routine, so haven't run into this
issue before. Learned something today!
Thanks to Simon, William and Andinus for your assistance!
- Rick
On 6/16/22 11:07, Simon Proctor wrote:
I
Here is the code:
...
} else {
return factors($q, @f);
}
...
Return the values during recursive calls too.
Output:
[2 2 5]
2
2
5
Simon Proctor @ 2022-06-16 19:07 +01:
> I think, and I don't have my computer to hand to double check but I
> think you
Hi Rick (and Simon)!
If I change the final (and only) call to `last`, and make it a call to
`exit` instead, the `Nil` disappears. Helpful?
Best Regards, Bill.
On Thu, Jun 16, 2022 at 11:07 AM Simon Proctor wrote:
>
> I think, and I don't have my computer to hand to double check but I think
I think, and I don't have my computer to hand to double check but I think
you want a return before your recursive.call to factors passing in @f.
When dealing with recursive functions you need to make sure what you're
returning back up the stack.
On Thu, 16 Jun 2022, 18:10 Rick Bychowski,
Hi Everyone,
I've been lurking quite a while, this will be my first post to perl6
users. I've written a lot of short scripts in perl5 for system admin
type stuff at home and work. Lately I'm playing with Raku, which is a
lot of fun. Error reporting is excellent, as is the online
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