yes, you're right,
so if think i prefer to 'allow a free intermixing of any number of steps (var
updates) with any other number of pred/fini pairs' which requires less brain
power to understand that the double encoding you are proposing :)
Something like:
public interface InnerLoopBuilder {
// variableIndex in [0..inits.length[
void addVariableUpdate(int variableIndex, MethodHandle step);
void addLoopExit(MethodHandle predicate, MethodHandle finisher);
}
MethodHandle loopMH(MethodHandle[] inits, Consumer<InnerLoopBuilder> consumer)
{ ... }
cheers,
Rémi
----- Mail original -----
De: "John Rose" <[email protected]>
À: "Rémi Forax" <[email protected]>
Cc: "Da Vinci Machine Project" <[email protected]>
Envoyé: Jeudi 27 Août 2015 01:28:20
Objet: Re: What can we improve in JSR292 for Java 9?
On Aug 26, 2015, at 6:06 AM, Rémi Forax < [email protected] > wrote:
it's less powerful but it seems you can encode all your examples of loops too.
No, I don't think so. Multiple pred/fini pairs implement multiple loop exits.
Any loop with an "if-return" in it has an exit distinct from the loop's main
test.
And each exit requires a different fini function, to encode a special result.
The match loop has this multi-exit character:
for (int i; i < a.len; i++) {
Object e = a[i];
if (ok(e)) return e; // first fini function; could also be e.payload
}
return null; // second fini function; could also be throwNotFound or
Optional.none
Sometimes even "&&" type predicate logic expands into multi-exit code, if the
loop needs to return a value that encodes which sub-predicate caused the exit.
— John
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