Re: [Caml-list] Local functions with arguments or closures ?

[Ville-Pertti Keinonen <will@iki.fi>]

On Jun 7, 2012, at 8:34 PM, Daniel Bünzli wrote:

> In the past I remember having indirectly benchmarked two different styles for writing local functions :

 …

> without being able to reach a conclusion. Is there any particular style that is definitively faster ? Does it maybe depend on the number of arguments and/or on whether loop is recursive or not ? 

As others have said the difference on modern CPUs shouldn't be too big for the loop itself.

However, if the inner function is a helper function (or a loop that only iterates a few times) and it's f that is called in a tight loop…it could be the case that without closures, f would allocate no memory, in which case there will be a definite difference.

It's still premature optimization unless you're actually running into problems.

Lambda lifting should be done by the compiler, not the programmer.  It probably wasn't worth it for OCaml because closures are dirt cheap compared to many other language implementations, and spending any significant time not allocating memory is quite rare.