The Scarpet language has the += operator, but it doesn't have -=. Should be there for simetry's sake.

It also does not have ++ or --. That's not a big deal, but the error message when one does use it is very cryptic (complaining about extraneous ; in a completely different place).

there will not be a ++ or -- support due to the parser its using. -= could be added but would not have intuitive usecase for collections or strings. For numbers you can always do foo += -5 instead of foo -= 5