On Sun, 2006-09-03 at 19:37 -0400, Peter Tanski wrote:
> // this mess is due largely to List
> val flxPty:Company =
> C (Cons ((D ("R&D", skaller,
> (Cons ((PU tryzelaar),
> Cons ((PU percossi),
> Cons ((PU tanski),
> Empty[SubUnit]) ))))), Empty[Dept]));
>
> var skaller:Manager =
> E (P ("John Skaller", "email hidden"), S 100000);
> var tryzelaar:Employee =
> E (P ("Erick Tryzelaar", "email hidden"), S 80000);
> var percossi:Employee =
> E (P ("Martin Percossi", "email hidden"), S 80000);
> var tanski:Employee =
> E (P ("Peter Tanski", "email hidden"), S 35000);
BTW: also note this won't work in Felix at present,
because flxPty tried to start work before tanski woke up :)
Generally, expressions are eagerly evaluated, statements
are executed in order of writing, and finally variant
constructors always make a heap copy of their argument:
so you'd be copying an uninitialised variable.
You either need to switch the order, 'semi-lazify' the data
by using a pointer, or 'really-lazify' it by using a closure.
The lazified forms provide sharing and permit updates.
In this case the problem could be eliminated if certain
conditions were met, which include:
* Use 'val' for all these, not var
* no intervening executable code
* reorder eval blocks in dependency order
Perhaps a better syntactic form would be a reordered let:
reorderlet x = y
and ...
--
John Skaller <skaller at users dot sf dot net>
Felix, successor to C++: http://felix.sf.net
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