Syntax Proposal: Anonymous Arguments

doodad-js Admin doodadjs at gmail.com
Fri Sep 23 21:20:45 UTC 2016


Should not “private fields” be a decorator ?

 

From: Jordan Harband [mailto:ljharb at gmail.com] 
Sent: Friday, September 23, 2016 4:32 PM
To: Kenneth Powers <ken at kenpowers.net>
Cc: es-discuss <es-discuss at mozilla.org>
Subject: Re: Syntax Proposal: Anonymous Arguments

 

@ is currently reserved for decorators, # currently for private fields. There aren't a lot of compelling syntax options left, to be sure.

 

On Fri, Sep 23, 2016 at 11:35 AM, Kenneth Powers <ken at kenpowers.net <mailto:ken at kenpowers.net> > wrote:

What proposal is "@" reserved for, by chance? I was trying to pick something that both wasn't used and can't be the name of a variable (e.g., underscore). I saw another proposal for "?" for partially applying functions, but that would be potentially ambiguous with the ternary operator.

 

As for resolving ambiguity, why not just do what Scala does <http://stackoverflow.com/questions/19916169/scala-arguments-of-nested-lambdas-with-short-syntax/19917720> ? It would seem to me that nesting these functions would be a sign you need to refactor anyway. 

 

As far as meriting its own syntax, that's why I referenced another language where the implementors found that it did merit its own syntax (though the underscore in Scala also does a lot more).

 

On Fri, Sep 23, 2016 at 2:00 PM, Jordan Harband <ljharb at gmail.com <mailto:ljharb at gmail.com> > wrote:

In Scala, the ambiguity of the underscore causes lots of confusion when you have nested functions - how is that handled in your proposal?

 

Bear in mind, I think it's a tough argument that `@ + 1` is so much better than `n => n + 1` that it warrants its own syntax.

 

Separately, the "@" is reserved for an existing proposal, so you'd have to come up with different syntax anyways.

 

On Fri, Sep 23, 2016 at 10:38 AM, Kenneth Powers <ken at kenpowers.net <mailto:ken at kenpowers.net> > wrote:

I have a proposal for new syntax in ES inspired by the placeholder syntax in Scala Functions <http://docs.scala-lang.org/overviews/quasiquotes/expression-details.html#function> .

 

Essentially, the idea would be to allow anonymous arguments. The most simple example would be a function which takes one argument (as far as the programmer is concerned):

 

    [1, 2, 3].map(@ + 1)

 

This would be the same thing as:

 

    [1, 2, 3].map(n => n + 1)

 

Just like in Scala, an anonymous function is created. This concept can be further extended in ES:

 

    [1, 2, 3].reduce(@0 + @1, 0)

 

Which would be the same thing as:

 

   [1, 2, 3].reduce((sum, n) => sum + n, 0)

 

Thoughts?

 

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