Pattern or range to the left, value to the right:

if case .enumThing(let x, _) = value { ... }
if 100..<200 ~= value { ... }

The pattern matching operator is pronounced “twiddle-eek” not “bacon rocket”. Not only more fun to say but tells you the order in which to type the symbols. If you insist you’d rather “eeky-twid” instead of proper twiddle-eeking, you can always wrap your own:

infix operator =~ {
  associativity none
  precedence 130
}

public func =~<T : Equatable>(a: T, b: T) -> Bool { return b ~= a }
public func =~<I : ForwardIndexType where I : Comparable>(value: I, pattern: Range<I>) -> Bool { return pattern ~= value }
public func =~<I : IntervalType>(value: I.Bound, pattern: I) -> Bool { return pattern ~= value }
public func =~<T>(lhs: T?, rhs: _OptionalNilComparisonType) -> Bool {return rhs ~= lhs }