Ocaml: Exporting a type in an mli file

Question

I have a file context.ml where a map is defined

module CtxMap = Map.make(struct type t = int let compare = compare end)

and a function map_get with type CtxMap.key -> 'a CtxMap.t -> 'a

How do I add the CtxMap declaration to the context.mli file? I can't find a way to do it as mli files can't contain code.

Answer 1

module CtxMap : Map.S with type key = int

在ocaml提供的map.ml文件中， map.ml函数的签名名称为S ， key是您要向外部模块公开的唯一抽象类型。

Answer 2

For reference, you can always do:

ocamlc -i -c context.ml

to output the default .mli file to stdout. The only issue with this (in your case) is that it expands the signature of the map.