mutability - pannous/warp GitHub Wiki

see constant and final

mutating modifying member functions are to be suffixed with an exclamation point (by the linter?)

# sketch: a C-like class
class string{
	data chars
	void upper!{
		chars[0]=chars[0].upper()
	}

variables can be force mutated by adding an exclamation point

x="test"
x.upper!

# same as x = x.upper()