I’m currently learning about functors in my university course on OCaml. Right now, I’m having trouble using an instance of a functor, here’s my code ensemble.ml: (* Signature ELT (element) *) module type ELT = sig type t val compare : t -> t -> int end (* Signature S (set) *) module typ…

I think you want to do one of the following: module A = struct type t = int let compare x y = x - y end module A : ELT with type t = int = struct type t = int let compare x y = x - y end What you had before was hiding the concrete type of A.t On a further note, I want to know how to acc…

[image] orbitz: module A = struct type t = int let compare x y = x - y end module A : ELT with type t = int = struct type t = int let compare x y = x - y end [image] orbitz: The name of a file is implicitly a module name. So if A is in foo.ml, then you would access it with Foo.A …

Never mind, the problem was that l1 wasn’t actually initialised as Test.t. I replaced it with l1 = Test.vide and it worked fine. The issue of accessing the modules from another file is still there. Even with open Ensemble. Can I see a clear example of how it’s done?

[image] LiDazhao: Am I missing something? I thought l1 is already of type A.t list since A.t = int as implemented. I’ve copied your code into TryOCaml, see the link <a href="https://try.ocamlpro.com/#code/(*'Signature'ELT'(element)'*)!module'type'ELT'='sig!type't!val'compare':'t'-$.'t'-$.'int!end!!(*'Signature'S'(set)'*)!module'type'S'='sig!type'elt!type't!val'vide':'t!val'element_de':''elt'-$.'t'-$.'bool!val'ajout':'t'-$.'elt'-$.'t!end!!(*'Implementation'A'of'signature'ELT'*)!module'A':'ELT'='struct!type't'='int!let'compare'x'y'='x'-'y!end!!(*'Functor'MakeL'with'signature'argument'E'of'type'ELT'that'produces'a'module'S'with'type'elt'='E.t'(same'element'type)'*)!module'MakeL(E':'ELT)':'S'with'type'elt'='E.t!=!struct!type'elt'='E.t!type't'='elt'list!let'vide'='$/$1!let'element_de'elt't'='List.exists'(fun'e'-$.'(compare'e'elt)'='0)'t!let'ajout't'elt'='elt'::'t!end!!module'Test'='MakeL(A)" rel="noopener nofollow ugc">here . If you click on the ‘Eval code’ button, you’ll see what the types are for the various modules. In particular, you’ll see…

Implementation of Functors

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yawaramin November 11, 2021, 11:11pm 3

One more thing, once you start organizing your code into multiple files, you will save yourself a lot of hassle by using dune to build the project instead of manually typing in ocamlc commands.

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Implementation of Functors

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