Basically, the Excluded Middle is for things neither True nor False.

Yeah okay I get it. The law basically states that 'not true' should be 'false' and vice versa.

I still don't get what's the use of this, or is this just a curiosity? It seems like the result is just a kind of ternary operator? Doesn't this still just compile to if(x.present) return x else y? Just with really obtuse syntax