Feature expressions would allow for this by allowing you to define the function multiple times, once per platform. Something like this (cljx) code:
#+clj (defn foo [] (println "Clojure implementation") #+cljs (defn foo [] (js/console.log "ClojureScript implementation") On 15 November 2014 14:59, Andrew Oberstar <[email protected]> wrote: > I apologize if this is naïve and/or incomplete; I'm very new to Clojure. > Would a better solution be to use something closer to protocols and > multimethods, where functions could be "polymorphic" by platform rather > than polymorphic by arguments? > > This would make it open for users to add support for platforms the library > author didn't support. At a quick glance, it looks like a feature > expression wouldn't allow for this. > > Andrew Oberstar > > > On Sat, Nov 15, 2014, 6:56 AM Daniel Kersten <[email protected]> wrote: > >> I didn't ask for feature expressions in the survey, but I've been wishing >> for a better way for writing cross-target code, especially libraries. >> >> I've never quite managed to bring myself to develop with cljx - I love it >> as a consumer of libraries, but I haven't quite managed to make it wo >> wellrk in my workflow for my own code, so haven't been using it. >> I've found it a bit too slow and clunky and don't quite know how it fits >> with other tools I use: eg, browser repl, figwheel, devcards. >> I also find it less than desirable to run yet another java process >> alongside my client nrepl, cljsbuild auto (or figwheel) and server clj >> application. Its already a heavier weight setup than I'd like. >> >> I imagine most of these concerns can be addressed in cljx itself, of >> course, but as it stands it's not ideal and improvements are needed >> -somewhere-. If it's part of the reader, though, then I don't need a >> separate stage. Plus any code invoking the reader would be target aware. >> >> On Sat, 15 Nov 2014 12:08 Julien Eluard <[email protected]> wrote: >> >>> Hi Colin, >>> >>> CLJX definitively does the job but at the price of being very brittle >>> and having to juggle with paths and classpaths. Also this is a leaky hack >>> as you have to make all tooling aware of it (editor, nrepl, ..). It usually >>> sort of work up to the point it doesn't. CLJX does the magic by generating >>> files and I must be aware of it while I would expect this to disappear with >>> Feature Expressions. >>> I would very much like to see something like that standardized and >>> transparent. >>> >>> Some specific answers: >>> 3. No. This goes much beyond. On the browser you have access to much >>> more than one would expect being part of a standard librairies. >>> See [1] for an example. >>> Also it's not clear how macro could be handled this way. >>> >>> 4. Node support (and related scenario) is a real problem. It's not clear >>> to me how to handle it and if this should be addressed by Feature >>> Expressions. See [2] for a concrete example. >>> >>> >>> [1] https://github.com/davidsantiago/hickory >>> [2] https://github.com/davidsantiago/hickory/issues/17 >>> >>> Julien >>> >>> 2014-11-15 4:09 GMT-03:00 Max Kreminski <[email protected]>: >>> >>> On Friday, November 14, 2014 7:22:39 PM UTC-8, Colin Fleming wrote: >>>> > Hi all, >>>> > >>>> > There's a discussion going on right now on clojure-dev ( >>>> https://groups.google.com/d/topic/clojure-dev/6pnIeXFRwnI/discussion) >>>> about the Feature Expressions functionality currently slated for Clojure >>>> 1.7. This was one of the most requested features in the recent state of >>>> clj/cljs survey, particularly by cljs users. However there seems to be a >>>> lot of confusion about exactly what the needs are here. I think everyone >>>> would be very interested in feedback, either here or on the clojure-dev >>>> thread if you have access, on why this is so important to cljs users. >>>> Specifically: >>>> > Is there something specific in the current proposal that is >>>> especially attractive to you, or is Feature Expressions more a proxy for >>>> "it should be easier to write cross-platform code"?Is there a strong >>>> argument for having this in the language, instead of in a tool like CLJX? >>>> Is this a fundamental failing of CLJX, or is the tooling perhaps just more >>>> awkward to use than it could be? >>>> > Could these needs be totally or mostly met by better cross platform >>>> libraries, like string and date handling?Would more features be useful than >>>> simply "this is CLJS code", i.e. would this be helpful for Node support? Is >>>> there no other way to get that support, i.e. through better libraries or >>>> macros? >>>> > I don't know the answers to any of these questions or have strong >>>> opinions about them since I don't use CLJS or CLJX, but I do write tooling >>>> that has to support them so I'd really like to understand this better. >>>> > >>>> > If any of you are interested in this and will be at the conj, >>>> there'll be an unsession about Feature Expressions there - please come and >>>> tell us what you think! >>>> > Cheers, >>>> > Colin >>>> >>>> I'm primarily a ClojureScript dev but I sometimes work with Clojure on >>>> the JVM as well. Here's my perspective. >>>> >>>> 1. I have no strong feelings about feature expressions in particular; >>>> I'm just excited to see the core team endorsing anything that will make >>>> cross-platform development simpler out of the box. >>>> >>>> 2. I have no major problems with CLJX (I suppose it's a bit of a hack, >>>> but it suffices for my purposes) except that of adoption. If I want to make >>>> any of the Clojure core repos CLJS-compatible, I can't use CLJX to write >>>> shared platform-agnostic code – the core team doesn't allow it. If a >>>> particular JVM Clojure library's maintainer doesn't like CLJX for whatever >>>> reason, I can't use that library in my CLJS project without forking it and >>>> maintaining the fork. At the moment, Clojure and CLJS code are incompatible >>>> by default, which feels like the opposite of how things "should be". >>>> >>>> 3. Better cross-platform libraries might get us halfway there but they >>>> won't completely obviate the need for CLJX, feature expressions, or >>>> something similar. When trying to write cross-platform exception handling >>>> code, for instance, I still regularly find myself needing to replace >>>> instances of "Exception" with "js/Error"; as long as these sorts of >>>> situations are still coming up I'll always want to have something like CLJX >>>> or feature expressions in my toolbox. >>>> >>>> 4. I can't really speak to this point too much, as I've never really >>>> run into any problems trying to work with e.g. Node vs browser JS. In the >>>> long term it might make sense to divide the "Clojure platform" into a set >>>> of specific features (e.g. macros, reified namespaces, clojure.string, etc) >>>> and allow users to test whether each of these features is "present" on any >>>> given implementation, but whether there exists an actual use-case for this >>>> is beyond me and it seems totally out of scope for the current discussion >>>> anyway. >>>> >>>> To get on my soapbox for a bit, I think the gap between Clojure and >>>> CLJS is gradually widening because the language as currently implemented >>>> makes it difficult to write and maintain cross-platform code. CLJX's >>>> feature set is all I really need, but right now every member of the >>>> community has to specifically "opt in" to writing cross-platform code by >>>> manually setting up CLJX for every project. Couple that with the fact that >>>> I specifically can't use CLJX when I'm contributing to the core libraries, >>>> and we wind up with a lot of duplicated effort on both sides of the >>>> Clojure/CLJS fence. >>>> >>>> The sooner we get feature expressions or something equivalent baked >>>> into core, the better. Only once the core team has blessed a particular >>>> solution will we see the current situation replaced by the "cross-platform >>>> by default" scenario I'd prefer. >>>> >>>> -- >>>> Note that posts from new members are moderated - please be patient with >>>> your first post. >>>> --- >>>> You received this message because you are subscribed to the Google >>>> Groups "ClojureScript" group. >>>> To unsubscribe from this group and stop receiving emails from it, send >>>> an email to [email protected]. >>>> To post to this group, send email to [email protected]. >>>> Visit this group at http://groups.google.com/group/clojurescript. >>>> >>> -- >>> Note that posts from new members are moderated - please be patient with >>> your first post. >>> --- >>> You received this message because you are subscribed to the Google >>> Groups "ClojureScript" group. >>> To unsubscribe from this group and stop receiving emails from it, send >>> an email to [email protected]. >>> To post to this group, send email to [email protected]. >>> Visit this group at http://groups.google.com/group/clojurescript. >>> >> -- >> Note that posts from new members are moderated - please be patient with >> your first post. >> --- >> You received this message because you are subscribed to the Google Groups >> "ClojureScript" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to [email protected]. >> To post to this group, send email to [email protected]. >> Visit this group at http://groups.google.com/group/clojurescript. >> > -- > Note that posts from new members are moderated - please be patient with > your first post. > --- > You received this message because you are subscribed to the Google Groups > "ClojureScript" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To post to this group, send email to [email protected]. > Visit this group at http://groups.google.com/group/clojurescript. > -- Note that posts from new members are moderated - please be patient with your first post. --- You received this message because you are subscribed to the Google Groups "ClojureScript" group. 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