Re:Pony – High Performance Actor Programming
by ShaneWilton on Sunday May 03, 2015 @08:14PM
(#9483641)
It's also worth noting that the language does have a None primitive, but the distinction from nil or null is that the concept of "nothing" is wrapped in it's own type entirely. This means that it would be a type violation for a method of return type String to ever return a None. Instead, a method that you expect to return a String or a None would need to have a union return type of (None | String).
It's analogous to Maybe, in Haskell.