"Unusable theoretical crap" is better than the current trap :-)
We hare "pure" in D, but still we have not grown up to actually
use it in Phobos, for higher order functions, or parallelism.
I don't think that Nordlöw presented a serious trap. This might
lead to bugs, yes, like anything else, for example: void
foo(int[] arr) { ... arr ~= ... }
Same error, if you expect arr to be changed outside the function.
In the case of Nordlöw: If you add a warning* it will issue many
warnings for a huge amount of perfectly fine code making the
warning useless. Forbidding it, would be even worse (since the
code wouldn't work, a more verbose alternative needs to be used
etc ..). For what? To prevent a possible bug that is easily found
and fixed? Wrong trade-off if you ask me.
* When should the warning actually be issued? Whenever a closure
is passed to map? Whenever a closure passed to map closes over
something where hasAliasing!T is true?
