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Comment by skrebbel | Hacker News Reader

0 < -1 < 2

To be fair, is there any mainstream language other than Python where that expression makes sense at all?

And even Python had to make explicit, syntactical support for it, and IMO it's a pretty non-obvious language hack. I mean, there's an invisible AND in there, that's pretty astonishing to me at least :-)

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Perl 5.32 will support this syntax: https://perldoc.pl/5.31.10/perldelta#Chained-comparisons-cap...

Works beautifully in Common Lisp. Of course, it is not mainstream.

? (< 0 1 2)

? (< 0 -1 2)

NIL

In Clojure:

   user=> (< 0 1 2)
   true

And

   user=> (< 0 -1 2)
   false

It's a big ask, to have a binary operator and ternary operator that use the same symbol.

It's honestly some fairly trivial AST-twiddling to support that feature. the compiler can simply detect cases where the left-hand-side of a comparison is /also/ a comparison and change the AST to make it two comparisons combined with an AND statement.

That said I find comparison chaining rather confusing and unexpected so I make a point of avoiding its use. Typing it out as two comparisons hardly saves any effort in any case.

I know, but it isn't a very useful feature, so why bother?

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