在OCaml中动态切换模块

我在OCaml中有一个由另一个模块参数化的模块，它表示一个数据结构（H=Hashtable，M=Map，L=LossyMap）。我现在希望通过命令行选择此数据结构

我创建主处理模块的方式是：

module HashSampler = MakeSampler(HashtableMatrix)
module MapSampler = MakeSampler(MapMatrix)

etc.

不幸的是，在它们之间多路传输的代码很难看：

match representation with
| "Hashtable" ->
       let matrix = HashSampler.create () in
           HashSampler.process_file matrix file
| "Map" -> 
       let matrix = MapSampler.create () in
           MapSampler.process_file matrix file

---

有没有更好的方法来防止代码重复？

您可以使用一流的模块。下面的一些示例代码显示了一种可能性

module type Sampler = sig
    type t
    val create : unit -> t
    val process_file : t -> string -> unit
end
module HashSampler : Sampler = struct
    type t = unit
    let create () = ()
    let process_file () file = ()
end
module MapSampler : Sampler = struct
    type t = unit
    let create () = ()
    let process_file () file = ()
end

let choose_sampler : string -> (module Sampler) = function
    | "Hashtable" -> (module HashSampler)
    | "Map" -> (module MapSampler)

let process representation file =
    let (module M) = choose_sampler representation in
    let matrix = M.create () in M.process_file matrix file

---

您可以使用第一类模块。下面的一些示例代码显示了一种可能性

module type Sampler = sig
    type t
    val create : unit -> t
    val process_file : t -> string -> unit
end
module HashSampler : Sampler = struct
    type t = unit
    let create () = ()
    let process_file () file = ()
end
module MapSampler : Sampler = struct
    type t = unit
    let create () = ()
    let process_file () file = ()
end

let choose_sampler : string -> (module Sampler) = function
    | "Hashtable" -> (module HashSampler)
    | "Map" -> (module MapSampler)

let process representation file =
    let (module M) = choose_sampler representation in
    let matrix = M.create () in M.process_file matrix file