Explanation of the "Single Arg Rule"

[zoffixznet]

It either needs to be documented, or if it is, indexed/made indexable by search engines.

[pmichaud]

I know I've been out of many recent conversations, but what is meant by "Single Arg Rule" here? Can you point to an example or discussion thread?

[zoffixznet]

The stuff where you put a comma after a single thing to make it do what you intend. That's what I heard it referred to as, but I don't know all the details of it, which is why I was trying to find the docs.

<Zoffix> m: my @list = (1,),; dd @list
<camelia> rakudo-moar 2126ed: OUTPUT«Array @list = [(1,),]␤»
<Zoffix> m: my @list = (1),; dd @list
<camelia> rakudo-moar 2126ed: OUTPUT«Array @list = [1]␤»
<Zoffix> m: my @list = (1); dd @list
<camelia> rakudo-moar 2126ed: OUTPUT«Array @list = [1]␤»
<Zoffix> m: my @list = 1,; dd @list
<camelia> rakudo-moar 2126ed: OUTPUT«Array @list = [1]␤»
<Zoffix> m: my $list = 1,; dd $list
<camelia> rakudo-moar 2126ed: OUTPUT«Int $list = 1␤»
<Zoffix> m: my $list = (1,); dd $list
<camelia> rakudo-moar 2126ed: OUTPUT«List $list = $(1,)␤»
<Zoffix> m: my $list = (1,),; dd $list
<camelia> rakudo-moar 2126ed: OUTPUT«List $list = $(1,)␤»

[stmuk]

I tried to explain this (probably not very well) in

https://perl6advent.wordpress.com/2015/12/14/day-15-2015-the-year-of-the-great-list-refactor/

Also there are details in S07 I think

S

On 17 June 2016 at 00:25, Zoffix Znet notifications@github.com wrote:

The stuff where you put a comma after a single thing to make it do what
you intend. That's what I heard it referred to as, but I don't know all the
details of it, which is why I was trying to find the docs.

m: my @list = (1,),; dd @list rakudo-moar 2126ed: OUTPUT«Array @list = [(1,),]␤» m: my @list = (1),; dd @list rakudo-moar 2126ed: OUTPUT«Array @list = [1]␤» m: my @list = (1); dd @list rakudo-moar 2126ed: OUTPUT«Array @list = [1]␤» m: my @list = 1,; dd @list rakudo-moar 2126ed: OUTPUT«Array @list = [1]␤» m: my $list = 1,; dd $list rakudo-moar 2126ed: OUTPUT«Int $list = 1␤» m: my $list = (1,); dd $list rakudo-moar 2126ed: OUTPUT«List $list = $(1,)␤» m: my $list = (1,),; dd $list rakudo-moar 2126ed: OUTPUT«List $list = $(1,)␤»

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4096R/EA75174B Steve Mynott steve.mynott@gmail.com

[zoffixznet]

Yes, it's in S07: https://design.perl6.org/S07.html#The_single_argument_rule

[JJ]

Where should this go then? List?

[AlexDaniel]

Wait, but we have this? https://docs.perl6.org/type/Signature#index-entry-%2B_%28Single_Argument_Rule_Slurpy%29

[JJ]

Reopened to address @AlexDaniel concerns.

[JJ]

Reopening this because #3268