[clean-list] observers in your plans?

[Edsko de Vries]

Hi Carlos,

As John showed, Clean's implementation of #! gives you what you need for this example, but is not as powerful as observer types. To make things work, Clean severely restricts the types of the variables that you can assign to (basically, they must be primitive types). Observer types are a lot more general, but whether or not this extra generality is worth the additional complexity of the type system I'm not sure.

Edsko