Along a similar vein, is it time to discuss optional typing a la flow/typescript which seem to be going a very similar direction with different tooling?
Though I'm really unsure about the need/bloat beyond tooling and kind of feel that generic expression support for catch blocks may be enough. -- Michael J. Ryan - track...@gmail.com - http://tracker1.info Please excuse grammar errors and typos, as this message was sent from my phone. On Mar 19, 2017 8:24 AM, "kdex" <k...@kdex.de> wrote: > Well, there has been some discussion of potentially adding something like > static type hints at some point in the future. > Pattern matching is a feature that inevitably requires type information at > runtime. > > So as long as the "optional typing" story isn't dead, I would assume that > pattern matching isn't quite dead either, it's just not in the currently > possible scope of things. > ECMAScript wouldn't be the only language which would have taken years to > come around to implementing type hinting: IIRC Python got its type hinting > feature pretty late, too. > > On Sunday, March 19, 2017 4:22:26 PM CET Michał Wadas wrote: > > Is there a serious push to add pattern matching to language? Does any > > popular dynamically typed language have pattern matching? > > I read that TC39 agreed on adding pattern matching to language in March > > 2013. 4 years later we don't have even stage 0 proposal - so I would > > consider it to be a dead end or wishful thinking. > > > > On Sat, Mar 18, 2017 at 5:16 PM, kdex <k...@kdex.de> wrote: > > > > > I'm not sure if embedding this idea into the language will make future > > > ideas about true pattern matching harder to implement or not. > > > Destructuring assignments are pretty slow from what I've measured, and > > > they still made it in, so I hardly see performance being a showstopper > here. > > > > > > On Saturday, March 18, 2017 12:18:22 PM CET Michael J. Ryan wrote: > > > > The if condition doesn't need to be limited to instance of... > > > > > > > > catch (err if !isNaN(err.status)) > > > > > > > > Aside: entering code in a phone is hard... > > > > > > > > > `instanceof` doesn't work across realms (iframes, for example). If > we > > > > > introduced conditional catch blocks, I'd want a more reliable > matching > > > > > mechanism than instanceof. > > > > > > > > > > On Fri, Mar 17, 2017 at 5:01 PM, Zach Lym <zach...@indolering.com> > > > wrote: > > > > > > > > > >> Firefox supports the following conditional `catch` syntax: > > > > >> > > > > >> try { > > > > >> let result = await (); > > > > >> } catch (e if e instanceof ErrorType) { > > > > >> ... > > > > >> } > > > > >> > > > > >> > > > > >> This was originally implemented in Spidermonkey as part of an ES > > > proposal > > > > >> around 2000, but it was rejected for unknown reasons [0]. A 2012 > > > email to > > > > >> this list suggesting standardization of the syntax was passed > over in > > > favor > > > > >> of waiting for a generic pattern matching facility [0][1]. Later > > > > >> discussion suggests that the pattern matching proposal would have > > > been very > > > > >> slow [2]. A proposal for a Java-like type-based conditional was > > > proposed in > > > > >> 2016, but was criticized for lacking generality [2]. > > > > >> > > > > >> If the above summary is accurate, I would like to try to > standardize > > > the > > > > >> vanilla syntax once again. It's imperative, general, and doesn't > > > preclude > > > > >> the use of any hypothetical pattern matching functionality. > > > > >> > > > > >> Javascript's control flow has improved dramatically in recent > years: > > > > >> promises got rid of callbacks, `async`/`await` clipped promise > > > chains, and > > > > >> classes make it easy to create custom Error objects that preserve > > > > >> stacktraces. Conditional catch is the last bit of syntax needed > to > > > make JS > > > > >> look like it was designed to handle asynchronous functions. > > > > >> > > > > >> Thoughts? > > > > >> > > > > >> -Zach Lym > > > > >> > > > > >> [0]: https://esdiscuss.org/topic/conditional-catch-clause# > content-10 > > > > >> [1]: https://esdiscuss.org/topic/conditional-catch > > > > >> [2]: https://esdiscuss.org/topic/error-type-specific-try-catch-bl > > > > >> ocks#content-14 > > > > >> > > > > >> _______________________________________________ > > > > >> es-discuss mailing list > > > > >> es-discuss@mozilla.org > > > > >> https://mail.mozilla.org/listinfo/es-discuss > > > > >> > > > > >> > > > > > > > > > > _______________________________________________ > > > > > es-discuss mailing list > > > > > es-discuss@mozilla.org > > > > > https://mail.mozilla.org/listinfo/es-discuss > > > > > > > > > > > > > > > > > > > > _______________________________________________ > > > es-discuss mailing list > > > es-discuss@mozilla.org > > > https://mail.mozilla.org/listinfo/es-discuss > > > > > > > > > _______________________________________________ > es-discuss mailing list > es-discuss@mozilla.org > https://mail.mozilla.org/listinfo/es-discuss > >
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