F# forward pipe operator in Swift

PipeOperators.swift

infix operator |> { precedence 95 associativity left }
infix operator <| { precedence 95 associativity right }

infix operator ?> { precedence 95 associativity left }

/// Forward pipe operator.
func |> <T, U>(arg: T, @noescape f: T -> U) -> U {
    return f(arg)
}

/// Backward pipe operator.
func <| <T, U>(@noescape f: T -> U, arg: T) -> U {
    return f(arg)
}

/// Forward pipe operator for optional argument.
func ?> <T, U>(arg: T?, @noescape f: T -> U) -> U? {
    return arg.map(f)
}