[tel]

To be clear, "closures" are merely an implementation of lamdbas which were invented in the 30s. I wouldn't mention it except you're trying to shame someone for not "knowing" that Smalltalk beat Haskell to the punch despite both of them borrowing from a much richer history.

To drive the point home, you can implement lamdbas (and thus Haskell) without using closures. In fact, this is easy in a pure language since bindings are static. One way to do this is to compile the language into a basis of combinators like SKI. These no longer have any notion of binding so we don't need closures. Likewise, you could compile it into a categorical semantics and maybe implement this on FPGAs—again, no need for closures.

Lamdbas are merely a syntax and theory. Closures are merely one interpretation given a Von Neumann machine.

[klibertp]

I happen to know all this; what I wanted to stress is not the nature of closures, which is exactly as you say, but that they were used since long ago in a "purely object oriented" languages, which - AFAIK - are not meant to implement lambda calculus in any shape or form.

GP wrote that - in short "everything in OOP is bad, let's use FP only". I responded with an argument that, in fact, certain OOP languages used FP features long before Haskell (because that's the example GP provided). I don't think the fact that closures are just one interpretation of an abstract concept of "lambda" is very relevant to this argument.

And about "shaming" people: I meant to gently point out that advocates for some cause should at the very least get their facts straight. Bashing some concept without knowing it well is the thing I objected to, a "not knowing it well" part by itself wouldn't be anything one should feel ashamed of.

[tel]

I suppose I read it overly antagonistically then. Honestly, the entire FP/OO thing is so draining. I wish we'd all just start talking about Church/Curry debates instead. It's dispense with most of the marketing mumbo jumbo.