Since the standard notation for open interval $(a,b)$ can be confused with the coordinates, gcd, and other stuffs (open brackets have been used A LOT!), I've seem notations like 

$]a,b[$ 

occurred in the book "Elementary Classical Analysis" by Marsden,
and we can denote half-open half-closed interval like this:

$]a,b]$ or $[a,b[$.