Re: x === x

From	Ben Bacarisse <ben.usenet@bsb.me.uk>
Newsgroups	comp.lang.javascript
Subject	Re: x === x
Date	2017-05-30 14:34 +0100
Organization	A noiseless patient Spider
Message-ID	<874lw231ui.fsf@bsb.me.uk> (permalink)
References	<JavaScript-20170530123255@ram.dialup.fu-berlin.de>

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ram@zedat.fu-berlin.de (Stefan Ram) writes:

>   In mathematics, usually, when »...« is a certain term, we have
>
> ... === ...
>
>   for the same term left and right.
>
>   In JavaScript, this does not always hold for expressions, albeit
>   possibly sometimes for different reasons:
>
> Math.random() === Math.random()
> NaN === NaN
> [] === []
> ( {} === {} )
> ( ()=>0 )===( ()=>0 )
>
>   In the first case, we cannot be sure that it will evaluate to
>   »false«, but this is is possibly.
>
>   The last three cases are similar, but it is also remarkable 
>   how one needs to add parentheses: no parens required for the
>   array, outer parens for the objects,

What's wrong with {} === {}?

> and two pairs of parens for the functions.

This one makes sense.  You are much more likely to want === in the body
of the arrow function so you want the grammar to cause (x) => x ===
... to mean (x) => (x === ...) rather than ((x) => x) === ...

-- 
Ben.

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Re: x === x Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-05-30 14:34 +0100
  Re: x === x Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-05-30 15:02 +0100
  Re: x === x Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2017-05-30 16:22 +0200
    Re: x === x Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-05-31 01:02 +0100
      Re: x === x Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2017-05-31 12:39 +0200
        Re: x === x Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-05-31 21:52 +0100
          Re: x === x Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2017-05-31 23:39 +0200
            Re: x === x Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-06-01 01:46 +0100
              Re: x === x Julio Di Egidio <julio@diegidio.name> - 2017-06-01 00:14 -0700
                Re: x === x John G Harris <niam@jghnorth.org.uk.invalid> - 2017-06-01 10:39 +0100
                Re: x === x Julio Di Egidio <julio@diegidio.name> - 2017-06-01 03:37 -0700
                Re: x === x John G Harris <niam@jghnorth.org.uk.invalid> - 2017-06-01 18:54 +0100
                Re: x === x Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-06-01 21:54 +0100
                Re: x === x John G Harris <niam@jghnorth.org.uk.invalid> - 2017-06-02 11:06 +0100
                Re: x === x John G Harris <niam@jghnorth.org.uk.invalid> - 2017-06-02 11:08 +0100
                Re: x === x John G Harris <niam@jghnorth.org.uk.invalid> - 2017-06-02 10:56 +0100
                Re: x === x Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-06-04 12:50 +0100
                Re: x === x John G Harris <niam@jghnorth.org.uk.invalid> - 2017-06-04 14:30 +0100
                Re: x === x Dr J R Stockton <J.R.Stockton@physics.org> - 2017-06-04 09:03 -0700
                Re: x === x Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-06-01 14:45 +0100
                Re: x === x Julio Di Egidio <julio@diegidio.name> - 2017-06-01 07:00 -0700
        Re: x === x Julio Di Egidio <julio@diegidio.name> - 2017-06-01 00:00 -0700

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