Igor Stasenko wrote:
> I don't see how [...] values can be implemented without modifying VM.
> You need to call some primitive to activate a block and execute
> statements. 
Yes, exactly as I suggested.

> Of course, having a source(or parse tree) , you can parse
> it and then convert each statement in separate block and execute them
> one by one. Then you don't need to modify VM code. 
Yes, you could do it that way, as Paolo and others including myself have 
thought of.

> But speed ...
>   
That is always an issue to be considered.
> Also, some use patterns don't fit the purpose and can lead to errors
> and undefined behavior.
>   
Well, anyone can make spagetti of out any feature in a language.

> Consider following:
>
> block := [ | temp |    temp := 1.   temp:= temp+1.   temp ].
>
> and somewhere later:
>
> result := block doInParralell
>
> Suppose you sending #doInParralell message to some unknown block
> (which contents is unknown at compile time). It's very interesting
> what results will be.
>
>
>   
As always you need to be congnizant of what features you are using and why.

All the best,

Peter