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A comment on Show HN: A JavaScript function that looks and behaves like a pipe operator. Parent comment

Re:Show HN: A JavaScript function that looks and behaves lik... by notpushkin on Wednesday September 27, 2023 @09:35AM (#37674457)
It feels a bit unnatural to pipe multiple arguments like that in JS, and you could inline them in the first call without losing legibility:

    a = c(b, 7) |> d(%)
It's the arguments added way down the line that are problematic:

    a = f((e(d(c(b))), 4), 5)
    a = ((b ~> c ~> d), 4 ~> e), 5 ~> f
    a = b |> c(%) |> d(%) |> e(%, 4) |> f(%, 5)
Smart pipes [1] were a bit nicer about that:

    a = b |> c |> d |> e(#, 4) |> f(#, 5)
Basically you would use # token whenever you wanted an expression and just a function name when you needed to pass a single argument. Best of both worlds IMO.

Perhaps it could even be extended for Curry-ish function syntax (although it isn't as obvious):

    a = b |> c(7) |> d
    a = d(c(7, b))
Too bad it was withdrawn.

[1]: https://github.com/tc39/proposal-smart-pipelines

[ Parent | on HN ]
Re:Show HN: A JavaScript function that looks and behaves lik... by notpushkin on Wednesday September 27, 2023 @09:58AM (#37674744)
Aside, but there's another kind of syntax possible here:

    const result = (
      await fetch(url)
        .json()
        ::Object.keys
        .map(key => ...)
        ::new ByteArray
    );
[ Parent | on HN ]
Re:Show HN: A JavaScript function that looks and behaves lik... by oispakaljaa on Wednesday September 27, 2023 @03:23PM (#37679899)
> P. S. When studying Haskell on a CS course in school, I used to define exactly the same squiggly arrow operator for my programs :-)

Haskell base already has the reverse application operator (&) which does the same thing. Not included in the prelude but can be imported from Data.Function. [1] It's defined as:

  (&) :: a -> (a -> b) -> b
  x & f = f x
Not that there's anything wrong with using your own definitions, just thought I'd point it out!

[1] https://hackage.haskell.org/package/base-4.18.1.0/docs/Data-...

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Re:Show HN: A JavaScript function that looks and behaves lik... by mg on Wednesday September 27, 2023 @03:47PM (#37680239)
This:

    a = f((e(d(c(b))), 4), 5)
Seems not to make sense. Replacing c(b) with x we get:

    a = f((e(d(x)), 4), 5)
Replacing d(x) with x we get:

    a = f((e(x), 4), 5)
Replacing e(x) with x we get:

    a = f((x, 4), 5)
What is that?
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Re:Show HN: A JavaScript function that looks and behaves lik... by notpushkin on Wednesday September 27, 2023 @05:03PM (#37681272)
Sorry, messed up parens here. It should have been:

    a = f(e(d(c(b))), 4), 5)
b is passed to c, then the result is passed to d, then to e along with 4 as a second parameter, and finally to f along with 5.
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Re:Show HN: A JavaScript function that looks and behaves lik... by mg on Thursday September 28, 2023 @02:07AM (#37685868) 

    a = f(e(d(c(b))), 4), 5)
That has 4 opening parenthesis and 5 closing parenthesis.

    b is passed to c

        b ~> c

    then the result is passed to d

        b ~> c ~> d

    then to e along with 4 as a second parameter

        b ~> c ~> d,4 ~> e

    and finally to f along with 5

        b ~> c ~> d,4 ~> e,5 ~> f
[ Parent | on HN ]
Re:Show HN: A JavaScript function that looks and behaves lik... by notpushkin on Thursday September 28, 2023 @04:41AM (#37686969) 

    b ~> c ~> d,4 ~> e
This reads as

    b ~> c ~> (d, 4) ~> e
to me. Sure, you can get used to it, but it’s pretty unnatural. Is this syntax used in any other languages?
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Re:Show HN: A JavaScript function that looks and behaves lik... by mg on Saturday September 30, 2023 @03:55AM (#37713492)
The nice aspect of "this ~> that" is that the meaning is simply "put this into that". And that it results in the shortest code.

An alternative would be:

    b ~> c ~> d ~> e(%,4)
Slightly longer, but maybe easier to read. Also easier to handle, as you can remove the fourth part " ~> e(%,4)" without having to change the third part.
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