module type Proov
= sig

    type t
    val a : unit -> t

  end

module Proov1
: Proov
    with type t = int

= struct

    type t = int

    let a = 10

  end

module type Proov = sig type t val a : unit -> t end
File "kodutöö.ml", line 14, characters 2-49:
Error: Signature mismatch:
       Modules do not match:
         sig type t = int val a : int end
       is not included in
         sig type t = int val a : unit -> t end
       Values do not match: val a : int is not included in val a : unit -> t
       File "kodutöö.ml", line 6, characters 4-21: Expected declaration
       File "kodutöö.ml", line 18, characters 8-9: Actual declaration