5 ms·

In JavaScript, "0 < -1 < 2" evaluates to true. The coercion rules were a big surprise to me when I first started to work in JS. Sometimes codes were obvious bu

In JavaScript, "0 < -1 < 2" evaluates to true. The coercion rules were a big surprise to me when I first started to work in JS. Sometimes codes were obvious but the underlying interpretation is a surprise call.

geerlingguy 7y ago
Reminds me of https://www.destroyallsoftware.com/talks/wat https://www.destroyallsoftware.com/talks/wat Javascript is convenient for many use cases, but it definitely violates POLA on many levels, in many situations!
saagarjha 7y ago
And it does in C as well!
- r00fus 7y ago
  So does this mean that JS does satisfy the principle of least astonishment for an experienced c-coder (something important when it was developed in the early 2000s)? In what language (other than a RPN based language like Lisp) would this expect to return something meaningful?
  - dingo_bat 7y ago
    > So does this mean that JS does satisfy the principle of least astonishment for an experienced c-coder No, this means don't use weird ambiguous syntax even if it is legal in the language.
  - saagarjha 7y ago
    Yes, you could say that. It preserves the order of operations and “reverse-truthiness” (i.e. boolean-to-integer) conversions from C.
skrebbel 7y ago
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 :-)
- benatkin 7y ago
  It's a big ask, to have a binary operator and ternary operator that use the same symbol.
  - Doxin 7y ago
    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.
    - benatkin 7y ago
      I know, but it isn't a very useful feature, so why bother?
- ghettoimp 7y ago
  Works beautifully in Common Lisp. Of course, it is not mainstream. ? (< 0 1 2) T ? (< 0 -1 2) NIL
  - deleted 7y ago
    [deleted]
  - jdminhbg 7y ago
    In Clojure: user=> (< 0 1 2) true And user=> (< 0 -1 2) false
deleted 7y ago
[deleted]

geerlingguy 7y ago

Reminds me of https://www.destroyallsoftware.com/talks/wat https://www.destroyallsoftware.com/talks/wat Javascript is convenient for many use cases, but it definitely violates POLA on many levels, in many situations!

saagarjha 7y ago

And it does in C as well!

r00fus 7y ago
So does this mean that JS does satisfy the principle of least astonishment for an experienced c-coder (something important when it was developed in the early 2000s)? In what language (other than a RPN based language like Lisp) would this expect to return something meaningful?
- dingo_bat 7y ago
  > So does this mean that JS does satisfy the principle of least astonishment for an experienced c-coder No, this means don't use weird ambiguous syntax even if it is legal in the language.
- saagarjha 7y ago
  Yes, you could say that. It preserves the order of operations and “reverse-truthiness” (i.e. boolean-to-integer) conversions from C.

skrebbel 7y ago

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 :-)

benatkin 7y ago
It's a big ask, to have a binary operator and ternary operator that use the same symbol.
- Doxin 7y ago
  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.
  - benatkin 7y ago
    I know, but it isn't a very useful feature, so why bother?
ghettoimp 7y ago
Works beautifully in Common Lisp. Of course, it is not mainstream. ? (< 0 1 2) T ? (< 0 -1 2) NIL
- deleted 7y ago
  [deleted]
- jdminhbg 7y ago
  In Clojure: user=> (< 0 1 2) true And user=> (< 0 -1 2) false

deleted 7y ago

[deleted]