It would be amazing to have clojure like protocols in JS even without `IFn`. I think it's very good feet and very useful in JS where each library has it's own flavored API. I wrote more about it here: http://jeditoolkit.com/2012/03/21/protocol-based-polymorphism.html#post
Also why would callable objects return `function` on `typeof(callable)`. As a matter of fact I think it should be `object` and something new like `Object.isCallable(object)` may be used to check for call-ability. This way old code either will reject non functions or will shim `Object.isCallable` to support new constructs. Regards -- Irakli Gozalishvili Web: http://www.jeditoolkit.com/ On Wednesday, 2012-04-11 at 11:54 , Brendan Eich wrote: > Michael Fogus wrote: > > I know some things about ClojureScript and would be happy to answer > > any direct questions. However, I think its notion (and Clojure proper) > > is that "functions are data are functions" is very powerful. > > > > > It's a great idea (I first met John McCarthy in 1977 when I was 16). Too > bad JS was not allowed to be "Scheme in the browser". > > > A lot of > > interesting patterns fall out of this as others have pointed out. > > > > > I'm ready to jump in with both feet, except for JS's age and the > possibility that too much code on the web counts on things like > > (typeof x == "function") <=> x() works and x.apply is the expected built-in > > No problem, you say, we can leave typeof alone and add a callable > predicate and evangelize that. Ok, provided the callable protocol uses > an ES6 private name (think gensym), any public name could be in use and > make a false positive when testing callability. > > So let's use a well-known private (unique, should say) name, e.g. > > module std { > ... > export const invokeName = Name.create("invoke"); > > export function callable(v) { > if (typeof v == "function") > return true; > if (typeof v == "object" && v != null) > return invokeName in v; // could be pickier but let's start here > return false; > } > } > > // make an object obj be callable: > obj[invokeName] = function (...args) { /* ... */ }; > > Looks ok, ignoring details such as how the client code gets the standard > unique name binding (import invokeName from "@std" or some such). > > One can't assume apply or call or other Function.prototype heritage is > in x just because callable(x) returns true. Callability is wider and > weaker than typeof-result "function". > > IIRC, security conscious folks do not want an attacker to be able to > make any old object callable. Cc'ing Mark for his thoughts. > > /be > _______________________________________________ > es-discuss mailing list > es-discuss@mozilla.org (mailto:es-discuss@mozilla.org) > https://mail.mozilla.org/listinfo/es-discuss > >
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