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Comment by kaeluka | Hacker News Reader

You make a claim here but don't back it up.

I think that a functional program, compiled to native code is STILL a functional program. You seem to not think that. Edit: If so, why?

Edit 2: Oh, maybe your point is that FP is statically typed?

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Of course not. Functional program compiled to machine code becomes imperative program.

It's now all about global variables (memory, stack and registers) and side effects. How is that functional?

Well, you can think of it as functional, if you consider every machine instruction to be function (whole machine state->whole machine state), but it's not practical and nobody really thinks about machine code like that. And anyway - if you want to think about it like that - evey imperative program becomes functional :)

I am not entirely sure that ASM can be used directly for functional programming. Also I am not entirely sure that functional == declarative although that is a very powerful combination. As far as I am concerned functional programming centers around the guarantee that f(x) has the properties associated with a function, i.e. for every x, exactly one f(x) is correct. That's why your data structures must be immutable. That's why you need referential transparency, etc. But how you calculate f(x) really doesn't determine whether this is FP or not. There's certainly a lot of power that can come from a language that can compose or decompose functions for you. But I wouldn't use that as a litmus test for FP.

But I suspect (not entirely sure, but suspect) that if you apply sufficient discipline, and omit from the equation the global necessities of registers, you can probably create functions in assembly, and call them in a functional way. In fact I suspect if this were not possible, then FP languages would not be possible to create.

But FP in ASM sounds really really painful.

But it accesses the global variables in way that is functional.. I.e does not overwrite memory that other variables have references to and such. Anyway, it is -- to me -- a superficial difference, but I think it causes this disagreement about whether you can program functionally in some other language. According to my view, you can, according to your's you can't. It comes down to your definition of what 'functional' is.

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