OCaml中具有多个参数的函子 [英] Functors with multiple arguments in OCaml

问题描述

我有以下情况:

module type M = sig type s = ...  end

module Make(P: Something) : (M with type s = P.t) = struct
   type s = P.t
   ...
end

可以很好地生成M类型的模块，该模块在其实现内使用类型为Something的模块的特定实现.

that works fine to generate modules of M type that use specific implementation of modules of type Something inside their implementation.

现在假设我将另一个模块定义为

Now suppose I have another module defined as

module type AU = sig
  val feed : float -> unitv
  val nth : int -> (float -> float)
  val reset : unit -> unit
end

具有多种实现方式

module SUAlg : AU = struct ... end
module MLAlg : AU = struct ... end
module ACEAlg : AU = struct ... end

问题的关键是，现在应该在两件事上对M模块进行参数化设置:Something模块和AU模块，以使其类似于

The point of the question is that the M module should be parametrized over two things now: a Something module and a AU module so that it's something like

module Make(P: Something) : (M with type s = P.t) = struct
   type s = P.t
   module Alg = MLAlg (* just an example *)
   ...
end

但我想有一个给定Something和给定AU的通用仿函数，它会生成一个模块，两者都具体化.有没有办法轻松获得它?

but I would like to have a generic functor that given a Something and given an AU it produces a module with both things concretized. Is there a way to obtain that easily?

由于functor语法很奇怪，而且我仍然很陌生，所以我不知道我要问的内容是否可以通过简单的方式解决.

Since functor syntax is quite strange and I'm still new to it I don't know if what I'm asking can be solved in a simple way or not.

预先感谢

推荐答案

是的，函子可以具有多个参数.语法如下:

Yes, a functor can have several arguments. The syntax is like this:

module Make_LOffset
            (V:Lattice_With_Isotropy.S)
            (LOffset : Offsetmap.S with type y = V.t and type widen_hint = V.widen_hint) =
struct
   …
end

然后可以将Make_LOffset(V)(LOffset)应用于函子.

The functor can then be applied with Make_LOffset(V)(LOffset).

在此示例中，为确保语法正确而从现有代码中提取了Make_LOffset的内容，并分别使用了两个签名Lattice_With_Isotropy.S和Offsetmap.S的模块V和LOffset对其进行了参数化.在with type … and type …部分这两个签名之间还有其他类型约束.

In this example, taken from existing code to ensure it is syntactically correct, Make_LOffset is parameterized by two modules V and LOffset, of respective signatures Lattice_With_Isotropy.S and Offsetmap.S. There are additional type constraints between the two signatures, the with type … and type … part.

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