[Caml-list] C++ templates to OCaml

[Caml-list] C++ templates to OCaml

[Jonathan Roewen]

Hi,

What's the best way to imitate C++ templates in OCaml? I have some
code that makes extensive use of templates that I want to rewrite in
OCaml, and using record types and functions is getting messy, and a
lot more convoluted than the C++ code.

Are objects the way to go here? And if so, can someone give me a
simple example of how this would work?

Jonathan

Re: [Caml-list] C++ templates to OCaml

[Jacques Carette]

Jonathan Roewen <jonathan.roewen@gmail.com> wrote:
> 
> What's the best way to imitate C++ templates in OCaml? 

<plug>
I have been quite successful at doing C++ template-like things in MetaOCaml.

In fact, using Functors and Modules judisciously, it is possible to hide all of the code-generation aspects and write 
quite straightforward code that can be instantiated in many different ways.

An earlier version of this work (joint with Oleg Kiselyov) is available at 
http://www.cas.mcmaster.ca/~carette/metamonads/, and has been accepted at GPCE 2005.
</plug>

Thanks for asking ;-)

Jacques

Re: [Caml-list] C++ templates to OCaml

[padiolea]

> Hi,
>
> What's the best way to imitate C++ templates in OCaml?

Well, simply use polymorphic types and functions.

> I have some
> code that makes extensive use of templates that I want to rewrite in
> OCaml, and using record types and functions is getting messy, and a
> lot more convoluted than the C++ code.
>
> Are objects the way to go here? And if so, can someone give me a
> simple example of how this would work?

read the ocaml manual,  or code in list.ml for instance in the
ocaml standard library.

> Jonathan
>
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Re: [Caml-list] C++ templates to OCaml

[Jonathan Roewen]

> I'd venture that you probably want functions and/or modules. Without any
> detail, though, it's difficult to say more.

Ok. Well, I want to rewrite the antigrain geometry library in OCaml
(www.antigrain.com). They make extensive use of chaining together
template classes. So, I'd use a module to represent each template
class, and polymorphic functions?

Re: [Caml-list] C++ templates to OCaml

[Benjamin Geer]

On 19/06/05, Jonathan Roewen <jonathan.roewen@gmail.com> wrote:
> So, I'd use a module to represent each template
> class, and polymorphic functions?

The book _Developing Applications with Objective Caml_ gives a good
comparison of modules, functors and classes, which might help you find
the best approach for your library.  See chapters 14, 15 and 16:

http://caml.inria.fr/pub/docs/oreilly-book/html/index.html

Ben

Re: [Caml-list] C++ templates to OCaml

[Brian Hurt]

On Sun, 19 Jun 2005, Jonathan Roewen wrote:

> Hi,
>
> What's the best way to imitate C++ templates in OCaml? I have some
> code that makes extensive use of templates that I want to rewrite in
> OCaml, and using record types and functions is getting messy, and a
> lot more convoluted than the C++ code.
>
> Are objects the way to go here? And if so, can someone give me a
> simple example of how this would work?

95-99% of the uses of templates are easily replaced with either universal 
types (so List<T> becomes 'a list) or with templates (see Set and Map). 
The remainder is template meta programming, for which you probably need 
pcaml, or I'd recommend rethinking the approach (template metaprogramming 
is, IMHO, one of things wrong with C++).

Brian