MLtonWeak - MLton Standard ML Compiler (SML Compiler)

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    signature MLTON_WEAK =
       sig
          type 'a t

          val get: 'a t -> 'a option
          val new: 'a -> 'a t
       end

A weak pointer is a pointer to an object that is nulled if the object becomes unreachable due to garbage collection. The weak pointer does not itself cause the object it points to be retained by the garbage collector -- only other strong pointers can do that. For objects that are not allocated in the heap, like integers, a weak pointer will always be nulled. So, if `w: int Weak.t` then `Weak.get w = NONE`.

- `type 'a t`
  the type of weak pointers to objects of type `'a`

- `get w`
  returns `NONE` if the object pointed to by `w` no longer exists. Otherwise, returns `SOME` of the object pointed to by `w`.

- `new x`
  returns a weak pointer to `x`.

Last edited on 2007-08-23 03:45:54 by MatthewFluet.