On Thu, Apr 9, 2015 at 4:04 PM, liorean <[email protected]> wrote: > Do we really need it? > Your «foo(1, ?, 2);» is equivalent to «a=>foo(1,a,2)». > Your «foo(?, 1, ???);» is equivalent to «(a,...b)=>foo(a,1,...b)». > Your «foo(1, ???, 2);» is equivalent to «(...a)=>foo(...[1,...a,2])». >
Not exactly. Using the placeholder syntax, `this` remains context dependent, whereas with your examples you get `null` as `this`. This might not seem like such a big deal until you consider it in combination with the proposed bind syntax [1]. Also in your examples, redefining `foo` will lead to different results. The placeholder syntax has a lot more room for optimization in the JIT compiler (the partially applied result is guaranteed to have no side effects for example, so the compiler can create a version of the original function where it can inline the specified arguments; less moving parts, easier to optimize). [1] http://wiki.ecmascript.org/doku.php?id=strawman:bind_operator > Also, the ? token is already taken by the ternary conditional > operator. Do we really want to overload it here for a nullary > operator/special form, when we have as low overhead syntax as we > already do in fat arrows for doing the exact same thing? > -- > David "liorean" Andersson > _______________________________________________ > es-discuss mailing list > [email protected] > https://mail.mozilla.org/listinfo/es-discuss >
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