To quote Jonathan Worthington: do not want(). We had a discussion on #perl6 tonight about how to implement want(), and basically came to no conclusion. Then I came up with the idea that any lazy implementor will come up with: drop it from the language.
The reason is that it seems impossible to come up with a way to determine context information efficiently. Consider the code 1+a(). One would expect want() in the body of a to return something like Num, right? But how could it get to that conclusion? After all there's a sub infix:<+>(Any $a, Any $b) defined (that will probably coerce to Num, but how the heck is the compiler supposed to know that, in the general case, from user supplied operators? after all we don't want to make "core" things special) that doesn't look like Num at all. Instead we should provide a very DWIMmy way to (lazily) create objects that behave differently in different contexts. Patrick pointed out that it can currently be done with return $value but role { method Bool { $code_for_boolean_context_here } }; (which would be fine by me, but perhaps might not be pretty enough for others). What do you think? And if you propose to keep want(), how would you think it could work? Cheers, Moritz