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[Caml-list] double-functors for types and values
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Brian Naylor
-
Jacques Garrigue
- Brian Naylor
-
Jacques Garrigue
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Date: | 2002-06-13 (15:36) |
From: | Brian Naylor <bwv211mail@y...> |
Subject: | Re: [Caml-list] double-functors for types and values |
--- Jacques Garrigue <garrigue@kurims.kyoto-u.ac.jp> wrote: > There 's something fishy in struct type btype = B.btype end: > if you're still inside B, you cannot refer to yourself as B. Whoops, sorry. You're right - the actual code uses more nested modules or type renaming, which I left out of the sample code. > Functors should incur three costs: > * type abstraction cost: if you depend on abstract types, some data > structure accesses cannot be optimized. I would like to see an example of an unoptimizable case > * function abstraction cost: all imported functions and (some?) > exported functions cannot be called directly. Expensive. So in the following code: module MakeA (A : sig type x end) = struct let foo = ... module MakeB (B : sig val quux : ... end) = struct let bar = ... end end Both [foo] and [bar] will not cost anything to evoke, but [quux] will cost an extra indirection since it was imported in the functor parameter? > * structure access cost: you have to dereference to get to your > closures. I believe it's cheap compared to the function abstraction > cost. Xavier Leroy had recently some figures showing that a method > call (double indirection) was not that much more expensive than an > abstract function call. Is this referring to closures over over local modules (using [let module]) only, or does it have an impact on top-level modules as well? Can someone come up with a link to the figures mentioned above? Thanks. __________________________________________________ Do You Yahoo!? Yahoo! - Official partner of 2002 FIFA World Cup http://fifaworldcup.yahoo.com ------------------- To unsubscribe, mail caml-list-request@inria.fr Archives: http://caml.inria.fr Bug reports: http://caml.inria.fr/bin/caml-bugs FAQ: http://caml.inria.fr/FAQ/ Beginner's list: http://groups.yahoo.com/group/ocaml_beginners