Need clarification on Scala literal identifiers (backticks)

Exactly. Using backticks, you can more or less give any name to a field identifier. In fact, you can even say

val ` ` = 0

which defines a variable with name (one character of whitespace).

The literal definition of identifiers is useful in two cases. The first case is, when there is already a reserved word of the same name in Scala and you need to use a Java library which does not care about that (and of course, why should it).

The other use case comes with case statements. The convention is that lower case names refer to match variables, whereas upper case names refer to identifiers from the outer scope. So,

val A = "a"
val b = "b"
"a" match {
  case b => println("b")
  case A => println("A")

prints "b" (if the compiler were dumb enough not to fail with saying case A were unreachable). If you want to refer to the originally defined val b, you need to use backticks as a marker.

"a" match {
  case `b` => println("b")
  case A => println("A")

Which prints "A".

Add There is a more advanced use case in this recent question method with angle brackets (<>) where the backticks were needed to get the compiler to digesting the code for a setter method (which in itself uses some ‘magic’ syntax).

Leave a Comment