Re: What does `:_` and/or `:_:` signify?

The code tried to do the same with `dd` as with `say`. There are two 
differences:

  * `dd`, as a kind of debug tool, doesn't assign any special meaning to
    named arguments so it's more than willing to give a Pair back with a
    colon syntax representation even if was understood as a named argument.
  * there is no `dd` method. I think nowhere in the core but at least
    not in the interface of a Pair.

By the way, I don't think the underscore has any special significance in 
these examples. It would be all the same with `:foobar`, `dd :foobar`, 
`dd foobar`, `dd :foobar:`

Hope this helps ^^

On 2023. 09. 26. 23:02, William Michels wrote:
> Hi Marton, Thanks for the reply.
>
> Below last example (in the REPL), does `dd` not work on Pairs?
> Or is this Indirect Object Notation at work?
>
>
> [3] > :_
> _ => True
> [4] > dd :_
> :_
> Nil
> [5] > dd _
> ===SORRY!=== Error while compiling:
> Undeclared name:
>     _ used at line 1
>
> [5] > dd :_:
> No such method 'dd' for invocant of type 'Pair'
>   in block <unit> at <unknown file> line 1
>
>
>
>
>> On Sep 24, 2023, at 23:40, Polgár Márton 
>> <[email protected]> wrote:
>>
>> Hi Bill,
>>
>> :_ is a Pair with the colon syntax that stands for "_" => True. In 
>> the first case, it got passed as a named argument and say ignored it. 
>> The second case was a method call using the colon syntax - the syntax 
>> lizmat challenged not so long ago. 
>> https://github.com/Raku/problem-solving/issues/384 so, ultimately, it 
>> was (:_).say, a normal say method call on a Pair.
>>
>> Cheers
>>
>>
>>
>> A(z) Galaxy eszközömről küldve
>>
>>
>>
>> -------- Eredeti üzenet --------
>> Feladó: William Michels <[email protected]>
>> Dátum: 2023. 09. 25. 7:15 (GMT+01:00)
>> Címzett: perl6-users <[email protected]>
>> Tárgy: What does `:_` and/or `:_:` signify?
>>
>> Hello,
>>
>> While playing around in an attempt to define new operators, I 
>> stumbled upon some curious results.
>>
>> In the REPL, trying `say :_` returns a blank line.
>>
>> In the REPL, trying `say :_:` returns `_ => True`.
>>
>> What is the meaning of this?
>>
>> admin@mbp ~ % raku
>> Welcome to Rakudo™ v2023.05.
>> Implementing the Raku® Programming Language v6.d.
>> Built on MoarVM version 2023.05.
>>
>> To exit type 'exit' or '^D'
>> [0] > say _
>> ===SORRY!=== Error while compiling:
>> Undeclared name:
>>     _ used at line 1
>>
>> [0] > say :_
>>
>> [0] > say :_:
>> _ => True
>> [0] >
>