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[Raphael Collet]

Dear Andreas,

> It seems that all other problems we had could be eliminated by two 
> work-arounds:
> 
> 1. Explicitly requesting the arguments before calls to '=='.

The implementation of '==' may not request its arguments if they are
equal.  Actually '==' requests its arguments only when it blocks on
them.  If you expect '==' to always need its arguments, they you must
request them explicitely.

> 2. Avoiding the "fun lazy" construction.
> 
> Regarding "fun lazy", I'm not sure what its precise semantics are 
> supposed to be now.

I thought I clearly explained this in the past (apparently I didn't).
The "fun lazy" construct no longer uses read-onlys (a.k.a. futures).
The statement

	fun lazy {Foo X} blah end

is expanded to

	proc {Foo X Y}
	   thread {WaitNeeded Y} Y=blah end
	end

> One of our problems was that under some circumstances it seems to
> generate a "simple" variable, which causes an exception on blocking.
> Since nobody here thoroughly understands what simple vars are and how
> they may appear in a program we would appreciate if somebody could
> enlighten us :-).

Simple variables are free variables.  This is an implementation term.  A
free variable is represented in the emulator by either an "optimized",
or a "simple" variable.  Optimized variables have no suspension list.

The definition of "fun lazy" above implies that, under ALL circumstances
it generates a free (simple) variable...  If you want "lazy futures",
you should use !!{ByNeed ...}, or even {ByNeedFuture ...}.


Cheers,

raph