AndreasKostler

object UnionTypes {
  private type ¬[A] = A => Nothing
  private type ¬¬[A] = ¬[¬[A]]

  private type ∈[S, T <: Disjunction] = ¬¬[S] <:< ¬[T#D]
  private type ∉[S, T <: Disjunction] = ¬¬[S] <:!< ¬[T#D]

  /** `S` is `T`. */
  type Is[S, T] = ∈[S, OneOf[T]#Or[Nothing]]

AndreasKostler

package model

import algebra.DeleteDealerErrors.SellIdError
import cats.MonadError
import play.api.libs.json._
import play.api.mvc.PathBindable
import scala.util.Try

final case class SellId(value: String)

AndreasKostler

Keybase proof

I hereby claim:

• I am andreaskostler on github.
• I am kandre1980 (https://keybase.io/kandre1980) on keybase.
• I have a public key ASAXdg4Wt3DUsCSjWq9LXIf6oCNka0lb1LbHvzYhbEyKMAo

To claim this, I am signing this object:

AndreasKostler

// Super simple, recursive flatten
// The _ means we have a weakly polymorphic type
// i.e. we don't care about what type _ is (it will, or will not, be resolved later)
// the type signature for flatMap on Seq is Seq[A] => (A => Seq[B]) => Seq[B]
def flatten(s: Seq[_]): Seq[_] = s flatMap {
  case s: Seq[_] => flatten(s) // If s is a Seq, we recursively flatten
  case s => Seq(s) // If s is atomic, we're done; just package up s
}

// degenerate case