(a is not b) results in (a == !b)

[shyamdsundar]

(a is not b) should actually be (a != b)

[epidemian]

In CofeeScript, is is a synonym of ==, and not is a synonym of !, so the current meaning makes sense.

# These are all equivalent.
a == !b
a == not b
a is !b
a is not b

[shyamdsundar]

Oh ok.

I am from python background where, "is not" means !=

Isn't the literal meaning ambiguous in the case of coffee script?

We can always have
a is (not b)

On 13 Oct 2013 14:16, "Demian Ferreiro" notifications@github.com wrote:

In CofeeScript, is is a synonym of ==, and not is a synonym of !, so the
current meaning makes sense.

These are all equivalent.a == !ba == not ba is !ba is not b

—
Reply to this email directly or view it on GitHubhttps://github.com//issues/3201#issuecomment-26212338
.

[thedrow]

I agree @shyamdsundar. It's confusing and misleading.

[vendethiel]

We have the isnt operator already.

[shyamdsundar]

I assumed that is not is equivalent to != and ended up having a few bugs that were quite hard to identify and locate. I believe that there are many people like me out there :-)

[vendethiel]

#814 (comment), #2419 and : #1551

[rlidwka]

is not is not the same as isnt... oops, I mean, is not isnt the same as isnt. Good luck learning english this way.

Just use != and get it over with, any kind of literate programming is a silly idea anyway. ;)

[zsitro]

isnt vs. is not is not clear haha. gave me trouble and lead to this thread.

[carlsmith]

It makes some sense ~ comparisons are just broken in JavaScript and CoffeeScript only sugars them ~ but the inconsistency between is not and isnt is a new issue CoffeeScript introduced.

[] is not [] # false
[] isnt []   # true

Ideally, isnt would be a contraction of is not, basically an alias.

[xyrius]

Definitely a tricky one. I encountered a hard to find bug because of this.
Intuitively I also used "isnt" for "is not", they should be the same as
they mean the same in English. "not" is just bad language design for "!".

On Fri, Sep 5, 2014 at 5:07 PM, Carl Smith notifications@github.com wrote:

It makes some sense ~ comparisons are just broken in JavaScript and
CoffeeScript only sugars them ~ but the inconsistency between is not and
isnt is a new issue CoffeeScript introduced.

[] is not [] # false
[] isnt [] # true

Ideally, isnt would be a contraction of is not, basically an alias.

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Reply to this email directly or view it on GitHub
#3201 (comment)
.

[adius]

@rlidwka Haha, great comment =D

[carlsmith]

Maybe isnt should've been named aint.

[michaelficarra]

Actually, it used to be.

[lydell]

Wow, I had no idea. That sure was some time ago.

$ git log --grep '\baint\b'
commit 985e0a080b14ea4d5a6456dbfbebe110cd3b9de0
Author: Jeremy Ashkenas <jashkenas@gmail.com>
Date:   Thu Dec 24 17:21:20 2009 -0800

    trading aint for isnt -- let's be serious

[michaelficarra]

Yep. Also, it's mentioned in the release notes for 0.1.3.