"ocaml_beginners"::[] polymorphic methods (and I've read the same named section of the manual :-)

Hello,

I have this code (just a container class) :

  class ['a] myclass (a_list : 'a list) =
  object 
    val the_list = a_list
    method map : 'b. ('a -> 'b) -> 'b myclass =
      fun f -> new myclass (List.iter f the_list)
  end

The compiler gives me this error :

  Characters 87-115:
      method map : 'b. ('a -> 'b) -> 'b myclass =
                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  This type scheme cannot quantify 'b :
  it escapes this scope.

I can't understand why ! (I REALLY can't, half a day I'm
on that...)

Thanks
Vincent






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