Philippe Sigaud <[email protected]> wrote:
Now, the 'real'/intriguing/mind-bending amb operator (from the 60's) does
like the Haskell implementation linked in SO does: backtracking on the
results to avoid some condition. If someone is up to the challenge of
implementing it in D, great! Maybe with closures? I never really thought
about it.
I guess the D syntax would be
auto x = amb([1,2,3]);
auto y =amb([4,5,6]);
x*y == 8; // forces desambiguation => the ambs explore the possibilities.
I believe this will only work with arrays as input. Either that, or I need
a way to make this work:
struct Foo( R ) if ( isForwardRange!R ) {
bool delegate( ElementType!R ) bar;
Filter!( bar, R ) range;
}
Or, well, something like it. I need a static type for a Filter that
delegates to a struct member, in this case bar.
assert(x == amb([2]));
assert(y == amb([4]));
There is only one value left, no more ambiguity. Maybe in this case an
'alias possibilities[0] this' could do the trick:
assert(x == 2);
assert(y == 4);
Can we do alias someArray[0] this; ?
For a simple assert like that, overloading opEquals ought to do the
trick, no?
--
Simen
