基本ocamloop问题
我正在尝试学习oCaml,我对以下程序无效的原因有疑问基本ocamloop问题,oop,ocaml,Oop,Ocaml,我正在尝试学习oCaml,我对以下程序无效的原因有疑问 class myClass2 = object method doSomething = Printf.printf "%s\n" "Doing something" end;; class myClass foo = object val dMember = foo method doIt = dMember#doSomething end;; let mc2 = new myClass2;; let mc = new myCl
class myClass2 =
object
method doSomething = Printf.printf "%s\n" "Doing something"
end;;
class myClass foo =
object
val dMember = foo
method doIt = dMember#doSomething
end;;
let mc2 = new myClass2;;
let mc = new myClass mc2;;
mc#doIt;;
我在尝试编译程序时收到的错误是:
File "sample.ml", line 6, characters 5-84:
Some type variables are unbound in this type:
class myClass :
(< doSomething : 'b; .. > as 'a) ->
object val dMember : 'a method doIt : 'b end
The method doIt has type 'a where 'a is unbound
这是无效的。非常感谢任何(我指的是任何)帮助。声明类型:
class myClass (foo:myClass2) =
OCaml对象的签名中不能有自由类型变量。由于未完全指定参数
foo
的类型,因此需要通过foo
类型中的自由变量参数化myClass
class ['a] myClass foo =
object
val dMember = foo
method doIt : 'a = dMember#doSomething
end;;
# let x = new myClass (new myClass2);;
val x : unit myClass = <obj>
# x#doIt ;;
Doing something
- : unit = ()
此定义具有以下类型:
class ['a] myClass :
(< doSomething : 'a; .. > as 'b) ->
object val dMember : 'b method doIt : 'a end
这难道不会破坏在myClass.doIt方法中使用结构类型的目的吗?
# let x = new myClass (new myClass2);;
val x : unit myClass = <obj>
# x#doIt ;;
Doing something
- : unit = ()