> Booleans can be true, false or maybe. […] Technical info: Booleans are stored as one-and-a-half bits.

Most languages would need at least ²log(3) bits. That’s about 1.58496250072, so that cuts more than 5% in storage.

I guess they’re using the fact that most real-life booleans have the value maybe, but don’t see how to implement this.