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[Caml-list] currying...
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Date: -- (:)
From: Chris Hecker <checker@d...>
Subject: [Caml-list] currying...

How does caml know when to call a function?  For example, say I have:

val f: int -> int -> int -> unit

and the definition of f is 

let f x y = Printf.printf "%d %d" x y;Printf.printf "%d"

so f actually takes two ints, prints them, and then returns a function that takes an int and returns unit.  From the val declaration above in a .cmi file, how can caml tell the difference between that f and this one:

let f x y z = Printf.printf "%d %d %d" x y z

How does it know "when" to call f, since you need a different number of parameters for the different definitions?  The top f prints x y when it's called with two parms, so it doesn't wait until all three parms have been passed.

I have a feeling I'm missing something fundamental here, or else the definition of a function internally has a field for its arity and it just partially applies until it reaches the total arity.  I thought I remembered seeing some documentation on this months ago, but I can't find it now...

It doesn't seem to partially evaluate the function or anything insane like that.

Chris

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