Re: [Caml-list] How much optimized is the 'a option type ?

[Yotam Barnoy <yotambarnoy@gmail.com>]

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I don't really understand how this could work. If the type of a function is
'a * 'b -> 'c then the function expects 2 tuple members, right? It has no
idea what their size is, because it can be called on any tuple. Now let's
say the tuple is float * int. If we unbox the tuple,  we get 3 words, with
the int comprising the 3rd word, and no metadata. How does the function
know how big each member is, or where to find each member? Are you assuming
we monomorphize the function?

Yotam


On Thu, Jan 30, 2014 at 4:31 PM, Jon Harrop <jon@ffconsultancy.com> wrote:

> Yotam wrote:
> > I don't think so. Without metadata, how do you know where one tuple
> member
> ends and another begins?
>
> Use static type information. When the type is known to be 'a * 'b you use
> the unboxed representation. Otherwise you default to the boxed
> representation.
>
> OCaml already does this to some extent because functions that accept a
> tuple
> are compiled to multi-argument functions (IIRC). So this would just be an
> extension to handle the return value too. The same idea could be used with
> many other types, e.g. unboxed optional arguments.
>
> Cheers,
> Jon.
>
>
>

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