Oh dang!
This may very well be a rakudobug. I've actually never used the sub form
of comb, only ever the method form, for which the "match" named
parameter definitely exists:
"a;b;c".comb(/\w/, match => True);
(｢a｣ ｢b｣ ｢c｣)
Someone will have to fix that and then the code from my mail will
retroactively become correct ;)
HTH
- Timo
On 16/11/2019 18:35, William Michels wrote:
> Hello Timo, and thank you for taking the time to explain how "comb"
> routine signatures work. I have no doubt your description is the
> correct way to use comb routine(s) in Raku/Perl6.
>
> First of all, I should preface my remarks by saying that I'm using
> Rakudo (moar) 2019.07.1, with the Linenoise module to run the
> Raku/Perl6 REPL. It has been suggested to me that my install might
> somehow be broken, because I tried to 'roll-my-own' Rakudo-Star
> release (basically I copied over pre-installed modules from my Rakudo
> 2019.03 install, and ran 'zef update').
>
> In any case, I haven't been able to get the code you posted to work. I
> checked all six examples in the REPL, and the last example I checked
> at the command line as well. I'm hoping someone on the list running
> Rakudo (moar) 2019.07.1 can confirm/refute my results:
>
>> #Timo
> Nil
>> comb(/\w/, "a;b;c", match => True);
> Unexpected named argument 'match' passed
> in block <unit> at <unknown file> line 1
>
>> comb(/\w/, "a;b;c", :match);
> Unexpected named argument 'match' passed
> in block <unit> at <unknown file> line 1
>
>> comb(/\w/, "a;b;c", :match(True));
> Unexpected named argument 'match' passed
> in block <unit> at <unknown file> line 1
>
>> comb(/\w/, "a;b;c", :!match);
> Unexpected named argument 'match' passed
> in block <unit> at <unknown file> line 1
>
>> comb(/\w/, "a;b;c", :match(False));
> Unexpected named argument 'match' passed
> in block <unit> at <unknown file> line 1
>
>> comb(/\w/, "a;b;c", 2, :match);
> Unexpected named argument 'match' passed
> in block <unit> at <unknown file> line 1
>
>> $*VM
> moar (2019.07.1)
>> exit
> mbook:~ homedir$ perl6 -e 'comb(/\w/, "a;b;c", 2, :match);'
> Unexpected named argument 'match' passed
> in block <unit> at -e line 1
> mbook:~ homedir$
>
> As for what's going on, I'm wondering if there might be an issue with
> "comb" signatures in general. There exists both a '(Str) routine comb'
> and a '(Cool) routine comb'. Maybe these two routines are somehow
> interfering with each other?
>
> Thank you, and any further help appreciated, Bill.
>
>
> On Sat, Nov 16, 2019 at 6:34 AM Timo Paulssen <t...@wakelift.de> wrote:
>> Hi Bill,
>>
>> In your repl examples you're actually passing the True or False as a
>> positional parameter, which makes it go into the slot for $limit, not the
>> slot for :$match.
>>
>> In order to pass true or false for the "match" named parameter you have
>> different syntactical options:
>>
>> comb(/\w/, "a;b;c", match => True) # maybe the simplest is using a pair
>>
>> comb(/\w/, "a;b;c", :match) # using "colon pair" syntax; it's syntax that
>> puts a colon at the beginning and makes a pair
>>
>> comb(/\w/, "a;b;c", :match(True)) # :match is short for match => True, and
>> :match(True) is long for match => True
>>
>> comb(/\w/, "a;b;c", :!match) # putting a ! after the : negates the pair,
>> i.e. it's now match => False
>>
>> comb(/\w/, "a;b;c", :match(False)) # same value
>>
>> And on top of that, you can add the third positional parameter to pass a
>> value for $limit
>>
>> comb(/\w/, "a;b;c", 2, :match) # output up to two results, as match objects
>>
>> Here's a few comments on the examples you pasted:
>>
>>
>>> On another note (or possibly the same note), I tried code similar to >
>>> Joe's with fair success. I was able to get the REPL to understand a >
>>> "True" or "False" parameter, but never in conjunction with a > "$limit"
>>> parameter. Is this the correct behaviour, and why?
>> The surprise here comes from Bool actually being derived from Int, and
>> therefore being totally acceptable values to pass for $limit.
>>>> #REPL > Nil >> say comb(/\w/, "a;b;c", False).perl; > ().Seq You can see
>>>> here that it gave no results; that's because it interpreted the False as 0
>>>> in the $limit parameter.
>>>> say comb(/\w/, "a;b;c", True).perl; > ("a",).Seq
>> Here the True is interpreted as 1 for $limit, giving you just "a", and it's
>> a string because the match named parameter wasn't given and defaulted to
>> False.
>>>> say comb(/\w+/, "a;b;c", True).perl; > ("a",).Seq
>> The difference between \w and \w+ isn't noticeable here, as the source
>> string only ever has single word character in a row, but you can try with
>> "ab;cd;ef" for example with both \w and \w+.
>>
>>>> say comb(/\w+/, "a;b;c", 2).perl; > ("a", "b").Seq >> say comb(/\w+/,
>>>> "a;b;c", 3).perl; > ("a", "b", "c").Seq >> say comb(/\w+/, "a;b;c",
>>>> 4).perl; > ("a", "b", "c").Seq >> say comb(/\w+/, "a;b;c", True).perl; >
>>>> ("a",).Seq
>> Same as above; True being interpreted as 1
>>
>>>> say comb(/\w+/, "a;b;c", 2, True).perl; > Too many positionals passed;
>>>> expected 2 or 3 arguments but got 4 in > block <unit> at <unknown file>
>>>> line 1
>> There's no syntax here that distinguishes 2, a positional parameter, from
>> True, also a positional parameter.
>>
>>>> say comb(/\w+/, "a;b;c", 2, :True).perl; > Unexpected named argument
>>>> 'True' passed in block <unit> at <unknown > file> line 1
>> The issue here is that :True is short for True => True, i.e. passing the
>> value True to the named parameter called "True", easy to get confused by the
>> error message here!
>>> Any help appreciated, Bill.
>> I hope the explanations make sense!
>> - Timo
