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ProcedureSyntax

"Procedure syntax" is a deprecated Scala feature that allows methods to leave out the result type and assignment character =. For example,

def debug { println("debug") }

This rule replaces procedure syntax with an explicit : Unit result type for both method implementations and abstract declaration.

// before: procedure syntax
def main(args: Seq[String]) { println("Hello world!") }
trait A { def doSomething }

// after: regular syntax
def main(args: Seq[String]): Unit = { println("Hello world!") }
trait A { def doSomething: Unit }

This syntax no longer exists in Scala 3 and therefore this rule only makes sense in Scala 2.