Swift ranges weirdness.

gistfile1.swift

import Foundation

let a = 1
let b = 10

func thisFailsToCompile() -> Bool {
    // type 'Range<Int>' does not conform to protocol 'IntervalType'
    let range = a..<b
    return range ~= 3
}

func butThisIsOk() -> Bool {
    return a..<b ~= 3
}

func thisIsAlsoOk() -> Bool {
    let range: HalfOpenInterval<Int> = a..<b
    return range ~= 3
}