On Mon, May 25, 2020 at 1:24 PM ToddAndMargo via perl6-users
<perl6-users@perl.org <mailto:perl6-users@perl.org>> wrote:
Hi All,
Looking at the following:
> my @things = <a5.1 a2.3 b1a23 a1b33 a1 a2rc2>.sort: *.Version; dd
@things; for @things {say $_;}
Array @things = ["a1b33", "a1", "a2rc2", "a2.3", "a5.1", "b1a23"]
a1b33
a1
a2rc2
a2.3
a5.1
b1a23
Other than not quite getting the alpha, beta, and
release candidate thing down, I do not understand:
.sort: *.Version
1) What does the `:` do?
2) Why the space?
3) What does the `*` do?
4) Is the dot before Version mean something other
than .Version being a method?
Yours in confusion,
-T
On 2020-05-25 14:00, Brad Gilbert wrote:
In the following the ｢:｣ makes it so you don't need parenthesis
(…).sort: …
(…).sort(…)
The reason there needs to be a space is so it isn't confused for an adverb.
｢*.Version｣ is a method call turned into a lambda.
Basically it creates a lambda where the only thing it does is call a
method named ｢Version｣
A ｢*｣ where a term is expected is an instance of Whatever.
If you use that with an operator it becomes a WhateverCode lambda.
sub say-the-type ( $_ ) {
say .^name
}
say-the-type *; # Whatever
say -the-type *.method; # WhateverCode
Hi Brad,
Thank you!
So the same as
> my @things = <5 2 1 33 22>.sort( *.Version )
[1 2 5 22 33]
Why don't these two work? Or at least give the
wrong answer. I thought Version was a method.
> my @things = <5 2 1 33 22>.sort.Version
No such method 'Version' for invocant of type 'Seq'
in block <unit> at <unknown file> line 1
> my @things = <5 2 1 33 22>.Version.sort
No such method 'Version' for invocant of type 'List'
in block <unit> at <unknown file> line 1
What is a "lambda" λ?
-T
