Re: [RFC] Pipe Operator, take 2

Just to clarify, I said it didn't look like it could be a pure AST implementation, and that it looks like you may need one additional instruction. It does look that way to me - if only to throw a sensible error specifically for pipes but also because it makes the imposition of specific behaviour for pipes a little easier, but it doesn't make it a super complicated thing. I also said I didn't know what the right answer was with regard to refs. I still don't, although I lean towards blocking them at the moment having spent a little more time looking at it. I don't really think we've had long enough to have this conversation properly. Cheers Joe On Tue, 6 Jul 2021 at 19:05, Larry Garfield <larry@garfieldtech.com> wrote: > On Mon, Jul 5, 2021, at 11:05 AM, Larry Garfield wrote: > > On Sat, Jul 3, 2021, at 9:12 PM, Larry Garfield wrote: > > > On Mon, Jun 7, 2021, at 2:00 PM, Larry Garfield wrote: > > > > Hi folks. Me again. > > > > > > > > A year ago, I posted an RFC for a pipe operator, |>, aka function > > > > concatenation. At the time, the main thrust of the feedback was > "cool, > > > > like, but we need partial function application first so that the > syntax > > > > for callables isn't so crappy." > > > > > > > > The PFA RFC is winding down now and is looking quite good, so it's > time > > > > to revisit pipes. > > > > > > > > https://wiki.php.net/rfc/pipe-operator-v2 > > > > > > > > Nothing radical has changed in the proposal since last year. I have > > > > updated it against the latest master. I also updated the RFC to use > > > > more examples that assume PFA, as the result is legit much nicer. i > > > > also tested it locally with a combined partials-and-pipes branch to > > > > make sure they play nicely together, and they do. (Yay!) Assuming > PFA > > > > passes I will include those tests in the pipes branch before this > one > > > > goes to a vote. > > > > > > Hi again. > > > > > > With PFA being declined, I've again reworked the Pipes RFC. > > > > > > 1) It now does not use PFA in any examples, but it does use Nikita's > > > first-class-callables RFC that looks like it's going to pass easily. > > > > > > 2) With major hand-holding from Levi Morrison and Joe Watkins, the > > > implementation has shifted a bit. It now evaluates left-to-right, > > > always, whereas the previous version evaluated right-to-left. That > is, > > > instead of $a |> $b |> $c desugaring into $c($b($a)), it now becomes > > > effectively $tmp = $a; $tmp = $b($tmp); $tmp = $c($tmp); That matters > > > if $b or $c are function calls that return a callable, as they are > then > > > only called when the pipeline gets to that part of the expression. > (If > > > all the functions involved are pure functions, then it doesn't make a > > > difference in practice.) > > > > > > 3) I included references to several existing PHP libraries that > > > implement similar logic, in mostly complex and ugly ways. > > > > > > 4) Of note, Brent posted a Twitter poll last week about pipes, and the > > > response was overwhelmingly in favor. > > > (https://twitter.com/brendt_gd/status/1408271132650885123) Naturally > a > > > Twitter poll is extremely unscientific, but I think between the > > > existing libraries and the response there the answer to the question > > > "is there actually a demand for this feature?" is unquestionably yes. > > > > > > 5) Examples have been reworked to be a bit prettier. > > > > > > 6) Added another language reference that has a pipe operator that > works > > > basically like described here. (OCaml) > > > > > > I am planning to take this version of the RFC to a vote on Monday or > > > Tuesday, as Tuesday is the last day possible to start a vote for 8.1 > > > features. > > > > > > --Larry Garfield > > > > Based on feedback on the PR, I've updated the RFC to forbid functions > > that pass or return by reference. They're not really useful in pipes > > at all, and were only supported before because the implementation > > happened to allow it. > > > > The PR hasn't been updated for that yet, but I figure that's easy > > enough to update post-vote if it passes. > > Sorry for the noise, but after some discussion with Joe it looks like > blocking references in pipes is actually much harder than it sounded like, > and would require a completely opcode based implementation rather than the > completely AST-based implementation. References on pipes are not really > useful but in practice they don't hurt anything. I've instead added more > tests to validate that they behave "as expected" and noted that in the RFC > instead. > > --Larry Garfield > > -- > PHP Internals - PHP Runtime Development Mailing List > To unsubscribe, visit: https://www.php.net/unsub.php > >