Scalastyle proposed rules (Types)

This page contains proposed rules for Scalastyle, for the category Types

Types

Type Annotation

Checks that types are annotated with the colon in the correct place This passes: def method(): Int = 1 This fails def method() : Int = 1 Rationale: This is standard behaviour in the scala library, and avoids confusion in certain circumstances.

Type Parameter Shadowing

Checks that a type parameter does not shadow another one:

def meth[A](a: A, f: A => A): List[A] = {
  val as = List(f(a))
  def inner[A](a: A) = f(a)
  inner(a) :: as
}

This code example does not compile and fails with the following cryptic error message:

<console>:10: error: type mismatch;
 found   : a.type (with underlying type A)
 required: A
         def inner[A](a: A) = f(a)
                                ^

Scalasyle can do a better job and raise a warning on the declaration of the type parameter of inner.