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Date: Sun, 18 Jun 2017 21:44:58 +0200
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Subject: Re: [PHP-DEV] [RFC]Discuss] Syntax for Arrow Functions
From: ilija.tovilo@me.com (Ilija Tovilo)

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Sorry, I wasn=E2=80=99t aware of that.

What do you think of the Ruby/Rust style syntax that Levi proposed a =
while back?

$someDict
    ->map(|$v| $v * 2)
    ->filter(|$v| $v % 3);

This one has a few advantages:

1. It has syntax (a lot of) developers are already familiar with
2. It has no ambiguities and is fully backward compatible
3. It=E2=80=99s the shortest of all options available (two `|` =
characters and one space)


> On 18 Jun 2017, at 20:48, Rasmus Schultz <rasmus@mindplay.dk> wrote:
>=20
> I understand it's not ambiguous to the parser if it's a keyword.
>=20
> I was referring to the visual ambiguity - the fn($x) part of the =
syntax is indistinguishable from a function-call.
>=20
>=20
> On Sun, Jun 18, 2017 at 8:42 PM, Ilija Tovilo <ilija.tovilo@me.com =
<mailto:ilija.tovilo@me.com>> wrote:
> > I don't agree that the fn keyword solves the ambiguity problem - it =
looks
> > exactly like a function call.
>=20
>=20
> Right. But it does solve the ambiguity if `fn` is a keyword which is =
what the RFC suggests.
>=20
>=20
> > On 18 Jun 2017, at 18:40, Rasmus Schultz <rasmus@mindplay.dk =
<mailto:rasmus@mindplay.dk>> wrote:
> >
> > I don't agree that the fn keyword solves the ambiguity problem - it =
looks
> > exactly like a function call.
> >
> > As for the backslash, my honest reaction is, ugh, please, no more
> > backslashes - PHP (and every other language) uses backslashes for =
escaping
> > in strings, it already looks pretty awkward in namespaces, this =
won't help.
> >
> >
> > On Sun, Jun 18, 2017 at 12:58 PM, Ilija Tovilo <ilija.tovilo@me.com =
<mailto:ilija.tovilo@me.com>> wrote:
> >
> >> The backslash has actually been one of the earlier options if I =
remember
> >> correctly.
> >> I definitely prefer the `fn` keyword as it=E2=80=99s only one =
character more but
> >> adds a better visual hint to the arrow function.
> >>
> >> I=E2=80=99m also not sure why we=E2=80=99d choose a different arrow =
(`=3D=3D>` or `~>`) when
> >> the ambiguity is solved through either a the backslash or the `fn` =
keyword.
> >>
> >>
> >>> On 15 Jun 2017, at 17:00, Bj=C3=B6rn Larsson =
<bjorn.x.larsson@telia.com <mailto:bjorn.x.larsson@telia.com>>
> >> wrote:
> >>>
> >>> Den 2017-06-15 kl. 15:34, skrev Fleshgrinder:
> >>>
> >>>> On 6/15/2017 3:29 PM, Bj=C3=B6rn Larsson wrote:
> >>>>> Seems like the constraints on this feature makes it hard to fly, =
i.e.
> >>>>> 1. Not a hackish implementation
> >>>>> 2. Non ambiguous syntax
> >>>>> 3. Easy to parse & use syntax for the human
> >>>>>
> >>>>> HackLang then prioritised 2 & 3 making the end-users happy, but
> >>>>> had to sacrifise a clean implementation. Any clue if this was a =
one-
> >>>>> time effort once it was done or something with a lot of =
drawbacks
> >>>>> in terms of maintenance, performance, evolution etc?
> >>>>>
> >>>>> r//Bj=C3=B6rn
> >>>>>
> >>>> On Reddit someone proposed the following syntax:
> >>>>
> >>>>    \() =3D> echo 'Hello, World'
> >>>>
> >>>> It is used by Haskell if I remember correctly and should not be
> >>>> ambiguous since `(` is not allowed in names of classes or =
functions. It
> >>>> actually aligns well with functions that are called with a
> >>>> fully-qualified name (e.g. `\printf('')`).
> >>>>
> >>>> Not sure if it would still require hacks though.
> >>>>
> >>> So applying that one on Sara's example becomes with some
> >>> options for the arrow:
> >>> 8. $someDict->map(\($v) =3D> $v * 2)->filter(\($v) =3D> $v % 3);
> >>> 9. $someDict->map(\($v) =3D=3D> $v * 2)->filter(\($v) =3D=3D> $v % =
3);
> >>> 10. $someDict->map(\($v) ~> $v * 2)->filter(\($v) ~> $v % 3);
> >>>
> >>> Interesting :)
> >>>
> >>> r//Bj=C3=B6rn
> >>>
> >>> --
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> >>
>=20
>=20


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