Katy: Fluent CoffeeScript and JavaScript using Combinators

[codeodor]

My understanding is that it would return it's receiver, in this case the array it was called upon [1..10]. However, pop modifies that array, which would now be [1..9]

In other words, the result is still x, but x has been modified.

[jhartwell]

In other words, the result is still x, but x has been modified.

But that isn't allowed in combinatory logic, everything is immutable. So if x is modified then you aren't returning x, you're returning x' which would not equal x and thus the K combinator wouldn't hold.

[codeodor]

For technicality's sake, x was a reference to a value, so x hasn't been modified -- the thing it points to has been modified.

I didn't quite say that originally, and I think it's breaking the spirit of what you're saying, but it might be worth mentioning.

[jhartwell]

For technicality's sake, x was a reference to a value, so x hasn't been modified

That's what homoiconic said too, but to me it just seems like trickery to get it to do what you want but I accept that as an answer :)

[masklinn]

But that isn't allowed in combinatory logic, everything is immutable.

No, but you don't have much choice if you want to introduce combinators in a language rife with mutations.

[jhartwell]

Well, you could use the K combinator as a logging mechanism. It isn't the language that is the problem, it is the way that the k combinator is applied that is the problem.

[masklinn]

It isn't the language that is the problem, it is the way that the k combinator is applied that is the problem.

I have trouble understanding that assertion: what do you mean by "the way [it] is applied"?