Suggestion: "if is" with dual-union and "else"

[quintesse]

Imagine this:

Foo|Bar gimmeEither() { ... }

and this code trying to use it:

if (is Foo x = gimmeEither()) {
    // We already know x is Foo here
} else {
    // NEW But couldn't the typechecker figure out x has to be Bar here?
}

For dual typed unions (which might be often used in cases like Result|Error) this might be useful.

[ikasiuk]

Is this any different from #74?

[quintesse]

Damn, I had forgotten about that one ;)
Closing