Hello, I think that Swift could use the 'double modulo' operator which is for example in CoffeeScript (some discussion can be found here https://github.com/jashkenas/coffeescript/issues/1971).
This operator, unlike normal modulo, takes sign from the divisor, not the dividend e.g. -10 % 3 == -1, but -10 %% 3 == 2. In practice, this operator is useful for 'cyclical' indexing. For example, it would be useful for calculating the real index into a collection when we are using an index outside of the range of valid indices and could be used to index into a collection using a negative index à la Python and Ruby (where [1,2,3,4][-1] == 4). The implementation would probably be something along these lines: infix operator %% { associativity left precedence 150 } func %%<T: IntegerArithmeticType>(lhs:T, rhs:T) -> T { return (lhs % rhs + rhs) % rhs } If accepted, this could be later incorporated into a method or operator that works directly with collections using their count property. Maybe the syntax could be something like [1,2,3,4] %% -1 == 4. Ideas, suggestions?
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