Re: why do i have to repeat so much here?

You may be interested in this long caml-list thread about precisely this
question:
  https://sympa.inria.fr/sympa/arc/caml-list/2012-10/msg00205.html
The short answer is "there is no well-understood way to do better without
design hacks".

Some people have designed meta-programming tools to macro-away some of the
boilerplate (eg. recently https://github.com/whitequark/ppx_import ). I
would recommend first trying to do it the usual way, to get a feeling of
how sufferable it actually is.


On Tue, Aug 19, 2014 at 7:50 AM, Martin DeMello [email protected]
[ocaml_beginners] <[email protected]> wrote:

>
>
> I'm learning my way around the module system, and trying to write a small
> Environment module that creates a record based on a given type. My code
> works, but it looks like i had to essentially write out the record
> definition thrice. Is there a better way to do this?
>
> Here's the definition of the module
>
> /--------------------------------
> $ cat environment.mli
>
> module type ENV = sig
>   type dict
>
>   type env = {
>     dict : dict;
>     op : Types.uop
>   }
> end
>
> module Make (Dict : sig type t end) : ENV with type dict = Dict.t
>
> $ cat environment.ml
>
> module type ENV = sig
>   type dict
>
>   type env = {
>     dict : dict;
>     op : Types.uop
>   }
> end
>
> module Make (Dict : sig type t end) = struct
>   type dict = Dict.t
>
>   type env = {
>     dict : dict;
>     op : Types.uop
>   }
> end
>
> \--------------------------------
>
> and I'm using it in the following code:
>
> /--------------------------------
> module Evaluator =
>   functor (Env : ENV) ->
>   functor (E : ENGINE with type dict = Env.dict) ->
>   struct ... end
>
> module Env = Environment.Make (Trie)
>
> module Eval = Evaluator.Evaluator (Env) (TrieEngine)
> \--------------------------------
>
> martin
>
>
>
> 
>