Default

Provides default values of case class-like types.

The Out type parameter is an HList type whose length is the number of fields of T. Its elements correspond to the fields of T, in their original order. It is made of None.type (no default value for this field) and Some[...] (default value available for this field, with ... the type of the field). Note that None.type and Some[...] are more precise than simply Option[...], so that the availability of default values can be used in type level calculations.

The apply method returns an HList of type Out, with None elements corresponding to no default value available, and Some(defaultValue) to default value available for the corresponding fields.

Use like

case class CC(i: Int, s: String = "b")

val default = Default[CC]

// default.Out is  None.type :: Some[String] :: HNil

// default() returns
//   None :: Some("b") :: HNil,
// typed as default.Out