PartialOperators.swift

/// Partially applies the right argument of a binary function
func partialRightApply<A, B, C>(_ f: @escaping (A, B) -> C, arg rhs: B) -> (A) -> C {
    return {lhs in f(lhs, rhs)}
}

prefix operator >

prefix func > <T: Comparable>(rhs: T) -> (T) -> Bool {
    return partialRightApply(>, arg: rhs)
}

prefix operator ?<

prefix func ?< <T: Comparable>(rhs: T) -> (T) -> Bool {
    return partialRightApply(<, arg: rhs)
}

prefix operator ?>

prefix func ?> <T: Comparable>(rhs: T) -> (T) -> Bool {
    return partialRightApply(>, arg: rhs)
}

/// Partially applies the left argument of a binary function
func partialLeftApply<A, B, C>(_ f: @escaping (A, B) -> C, arg lhs: A) -> (B) -> C {
    return {rhs in f(lhs, rhs)}
}

postfix operator >?

postfix func >? <T: Comparable>(lhs: T) -> (T) -> Bool {
    return partialLeftApply(>, arg: lhs)
}

postfix operator <?

postfix func <? <T: Comparable>(lhs: T) -> (T) -> Bool {
    return partialLeftApply(<, arg: lhs)
}