On mobile, sorry for top posting.
Multiple $$ means the resulting closure will accept multple arguments.
I'm definitely against dropping the ($$) on the right hand side because it
would use non standard symbol lookup rules.
$x = trim;
This normally will look up a constant, and then apply barewords if it
doesn't exist. Let's not go down the road of special casing things.
On Jan 20, 2017 3:53 AM, "François Laupretre" <[email protected]> wrote:
> Le 19/01/2017 à 22:53, Levi Morrison a écrit :
>
>> On Thu, Jan 19, 2017 at 11:12 AM, François Laupretre <[email protected]>
>> wrote:
>>
>>> Le 19/01/2017 à 13:54, Levi Morrison a écrit :
>>>
>>>> The `|>` symbol would be the piping operator with these semantics:
>>>> 1. Evaluate the left-hand side.
>>>> 2. Evaluate the right-hand side. Assert that the result is
>>>> callable.
>>>> 3. Pass the result from 1. as the single argument to 2.
>>>>
>>>
>>> May I suggest extending your 3rd rule to : when the right hand side has
>>> the
>>> form of a function call, insert the result from 1. as first argument of
>>> 2.
>>> This way, right hand side may specify additional arguments
>>>
>> If we only had `|>` this may be good but since we are also proposing
>> `$$` then this renders your suggestion unnecessary:
>>
>> $string |> trim($$)
>>
>> Would work just fine with no performance overhead.
>>
>> Additionally, you could write:
>>
>> $input |> array_map($fn, $$)
>>
>> Or:
>>
>> $input |> array_filter($$, $fn)
>>
>> Basically, `$$` gives the flexibility of passing additional arguments
>> and keeps `|>` simple. No need for additional rules for `|>`.
>>
>
> Right, I just suggest to make the '$$' optional when used as first arg of
> a rhs call. Except complex cases like array_xx() functions which will
> generally require an explicit '$$', most cases will feature a '$$' as first
> arg of a function call. This may be considered as better because more
> explicit, but I think the case is prominent enough to justify this
> 'shortcut'.
>
> Another question: Will you accept several occurences of '$$' in a RHS ?
>
> Last, a cosmetic suggestion : replace '$$' with '$<' (more explicit as
> 'input data', imo).
>
> Regards
>
> François
>
