Re: [RFC][Discuss] Arrow Functions

On Mon, May 29, 2017 at 10:48 PM, Levi Morrison <levim@php.net> wrote: > Based on the discussion there are a few different syntax choices that > we probably just need to vote between. It's a feature that people seem > to want but everyone seems to prefer a different syntax choice. > > 1. fn(params) => expr > 2. function(params) => expr > > 3. (params) ==> expr > 4. (params) => expr > TL;DR - I'll be happy with whatever the group can agree on, with a personal ordering of: 1 > 3 > 2. I excluded #4 because I just don't see how you disambiguate this: [ ($x) => $x ] . It's already valid syntax: https://3v4l.org/NedDu . With zero or 2+ args it's disambiguable, but one arg has to be possible or it's a no-go. > This is why everyone is so divisive. All options have drawbacks. > Additionally some people don't like binding by value and would prefer > ref, and others really would be against by-ref. > Again, I'll accept the group's opinion because I don't care enough to block it, but I'm registering my preference for the record, as by-ref. > Which brings me to an option I don't think was ever discussed on list: > > [](params) => expr // binds no values > [=](params) => expr // binds by value > [&](params) => expr // binds by reference > As a C++ developer, I have no inherent problems with this **in theory**, but I agree with your statement that it's a bit symbolic soupish. I also suspect that we'll run into grammar ambiguities. Imagine: [ []($x) => $x ]. This is current legal syntax (at the point of compilation) because it *could* be interpreted as an array with a single element (value $x) who's key is the result of calling a function defined by an empty array passing a single arg ($x). It's invalid at runtime (See: https://3v4l.org/IcK3B ), but that means special casing our way around the ambiguities. Further, if we're going to follow the C++ model, we'd be well suited to allow explicit per-var by-val/by-ref syntax, e.g.: [$foo, $bar]() => $foo * $bar Again, this is legal syntax to the parser, but now it's even potentially current legal syntax to the runtime (assuming is_callable([$foo, $bar]). So yeah, probably doesn't fit PHP, but good thinking outside the box. :D -Sara