Hi Elizabeth!
How would you write that expression using the feed operator?
Thanks,
Shimon
> On Mar 3, 2024, at 7:22 AM, Elizabeth Mattijsen <l...@dijkmat.nl> wrote:
>
>> On 3 Mar 2024, at 03:32, ToddAndMargo via perl6-users <perl6-us...@perl.org>
>> wrote:
>>
>>> On 3/2/24 05:13, Elizabeth Mattijsen wrote:
>>>> <afoo12 afoo2>.sort(*.split(/\d+/, :kv).map({ (try .Numeric) // $_}).List)
>>
>>> Hi Elizabeth,
>>> It works perfectly. Thank you!
>>> I have no idea why, I will ask you in another post
>> Would you take apart your sort piece by piece and explain
>> each part?
>
> Actually, the expression can be refined a bit:
>
> say <afoo12 afoo2>.sort(*.split(/\d+/, :v).map({ (try .Int) // $_}).List)
>
> Sort works by using `cmp` semantics by default.
>
> If `cmp` is called on two lists, it will `cmp` each element and return the
> result of the first comparison that did not produce `Same`.
>
> If you call `sort` with a Callable that takes only one argument, it is taken
> as the producer of the actual values that will be compared, basically doing a
> Schwartzian transform under the hood.
>
> A whatever code (which is what we specified here) produces a Callable with a
> single argument. So we'll be doing a Schwartzian transform under the hood.
>
> The `split` splits the value (each element in the list) on any set of Numeric
> characters (`\d+`), *but* also produces the strings that were split on
> (`:v`). (The previous version had .kv, but that just produces more identical
> entries in the list, which only will make comparisons slower).
>
> The resulting values from the `split` are then mapped to an integer value (if
> possible: `(try .Int)` and if that fails, just returns the value (`// $_`).
> (The previous version had `.Numeric`, which will also work, but since `\d+`
> can only produce integers, it's an extra unnecessary step).
>
> Then convert the `.Seq` that is produced by the `.map` to a `List`.
> Otherwise we'd be comparing `Seq` objects, and the semantics of those are
> undefined.
>
> So for `"afoo12" cmp "afoo2"`, we will be doing `("afoo", 12) cmp ("afoo",
> 2)`. Which would do: `"afoo" cmp "afoo"`, which produces `Same`, and then do
> `12 cmp 2`, which will return `More`, and thus will cause swapping the order
> of <afoo12 afoo2>.
>
>
> Hope that made sense!
