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3 points by akkartik 1531 days ago | link | parent

That's a great point. As I've built this, the keystone example in my mind has been the `square` function:

    x square = x x *
So it's really funny that I haven't added it yet. Now added.


2 points by zck 1531 days ago | link

Nice!

Is it that you're trying to reduce stack juggling? That's hard to understand from simple examples (that you need to have to grok the syntax). Maybe compare something like finding the hypotenuse of a right triangle given the two other sides. Without naming arguments, you'd have to do something like:

  hypot = dup * swap dup * + sqrt
But with named arguments:

  hypot x y = x x * y y * + sqrt
That seems a little easier to read, but even the original isn't so complicated. Is there an example that makes it more obvious why it's better? Even your `square` example is more tokens than with stack juggling (without arguments, `square = dup *` is just four tokens, compared to six with named arguments). I'd say the with-arguments one is easier to read, but I've far less familiar with stack-based postfix programming.

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2 points by akkartik 1531 days ago | link

Yeah, some other polynomial might be a better example. The Pythagorean formula has a clean separation when it comes to which args each term uses. How about the roots of a quadratic equation when you start out with a, b and c on the stack?

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2 points by zck 1530 days ago | link

Yes, that is definitely simpler, although the formula is more esoteric. At least, for me, it triggers the "I was taught this in school and haven't used it since" filter.

Maybe something like:

  total-price cost-per-item number-of-items shipping-cost-per-item rush-cost = cost-per-item number-of-items * shipping-cost-per-item number-of-items * + rush-cost +
This doesn't seem super great; it could be refactored to use each thing once, but it's late and I can't think of any better example.

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2 points by akkartik 1530 days ago | link

You're right that in general any such example can be refactored to reduce stack operations. That's even a fun game for many Forth programmers to play. (We lispers have our own equivalents.) But it usually makes the code less comprehensible, in my experience.

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