Rounding

The round() built-in function takes an optional second argument. From a typing perspective, round() has two overloads, one with 1 parameter, and one with two. For both overloads, optype provides separate operand interfaces: CanRound1[R] and CanRound2[T, RT]. Additionally, optype also provides their (overloaded) intersection type: CanRound[-T, +R1, +R2] = CanRound1[R1] & CanRound2[T, R2].

operator			operand
expression	function	type	method	type
`round(_)`	`do_round/1`	`DoesRound`	`__round__/1`	`CanRound1[+R=int]`
`round(_, n)`	`do_round/2`	`DoesRound`	`__round__/2`	`CanRound2[-T=int, +R=float]`
`round(_, n=...)`	`do_round`	`DoesRound`	`__round__`	`CanRound[-T=int, +R1=int, +R2=float]`

For example, type-checkers will mark the following code as valid (tested with pyright in strict mode):

x: float = 3.14
x1: CanRound1[int] = x
x2: CanRound2[int, float] = x
x3: CanRound[int, int, float] = x

Furthermore, there are the alternative rounding functions from the math standard library:

operator			operand
expression	function	type	method	type
`math.trunc(_)`	`do_trunc`	`DoesTrunc`	`__trunc__`	`CanTrunc[+R=int]`
`math.floor(_)`	`do_floor`	`DoesFloor`	`__floor__`	`CanFloor[+R=int]`
`math.ceil(_)`	`do_ceil`	`DoesCeil`	`__ceil__`	`CanCeil[+R=int]`

Almost all implementations use int for R. In fact, if no type for R is specified, it will default in int. But technically speaking, these methods can be made to return anything.