How would one implement OCaml / F#'s "function" construct in Scala?

Question

A common tendency I've discovered in Scala is something like this:

def someFunction(a: SomeClass) = a match { ... }

And from there on a is never used ever again. This pattern is SO common in FP that OCaml and F# have a built-in construct to let you ditch that parameter entirely.

Instead of writing this:

let someFunction a = 
  match a with
  | 0 -> true
  | _ -> false

you can simply write this:

let someFunction =
  function
  | 0 -> true
  | _ -> false

So my question is, is it possible to write something like this in Scala?

def someFunction = function {
  case 0 => true
  case _ => false
}

Saving an otherwise unnecessary parameter.

I've attempted to write it as a function that takes a call-by-name parameter, but Scala won't let me make an empty match block.

Is it possible? Or does scala perhaps already have something like this built in?

Answer 1

Use a function instead of a method:

val someFunction: Int => Boolean = {
  case 0 => true
  case _ => false
}

You have to explicitly write the type annotations, but that must not be a drawback - for API usage it is useful documentation.