Open Radar

 
Swift officially only supports custom operators using a small set of characters.  However, the current Swift compiler accepts many Unicode characters for custom operators.  This allows some elegant constructions:

operator infix ≤ {associativity none precedence 130}
func ≤<T : Comparable>(a: T, b: T) -> Bool {
    return a <= b
}
println(1 ≤ 2)

operator infix → {associativity left precedence 105}
func →<ArgType,ResultType>(arg: ArgType, f: (ArgType) -> ResultType) -> ResultType {
    return f(arg)
}
"arrow" → println

operator infix ∑ {associativity none precedence 125}
func ∑(sequence: Double[], transform: (Double) -> Double) -> Double {
    return reduce(map(sequence, transform), 0, +)
}
println([1, 2, 3, 4] ∑ {$0*$0})

I request that the current support of Unicode custom operators become an official part of the language.