Using unicode variables in Scala tuple assignment

Question

val ©® = 1
val (©, ®) = (1, 2)

Line 1 works fine in both Scalac and the REPL but line 2 chokes on both.

Is this a bug? Or is there a special syntax that I'm missing?

Disclaimer: I know that using non-ASCII variable names is a terrible idea. I came across this by complete accident. My codebase isn't full of wacky symbols, I swear. Please don't lynch me :)

Answer 1

Maybe this helps:

scala> val (x, y) = (1, 2)
x: Int = 1
y: Int = 2

scala> val (X, Y) = (1, 2)
<console>:7: error: not found: value X
       val (X, Y) = (1, 2)
            ^
<console>:7: error: not found: value Y
       val (X, Y) = (1, 2)
               ^

What happens is that unicode is treated like uppercase characters when it comes to pattern matching, which means that, since it "starts" with an "uppercase letter", it thinks you are comparing to a constant instead of assigning values.

Another example:

val © = 1
val ® = 3

(1, 2) match {
  case (©, ®) => "Both match"
  case (_, ®) => "Second matches"
  case (©, _) => "First matches"
  case _      => "None match"
}

results in

res0: java.lang.String = First matches