Created
September 20, 2019 13:39
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Non Breaking Option
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import scalaz.Monad | |
import scalaz._, Scalaz._ | |
object OptionTest { | |
case class User(name: String, image: String) | |
// Gets a user, optionally | |
def getUserOp: Option[User] = Some(User("Paul", "paul.jpg")) | |
// later, refactor so that we get a user always! | |
def getUserExactly: Id[User] = User("Paul", "paul.jpg") | |
// can only be used with Option[User], so this usage would break when we refactor getUserExactly | |
def extractImage(userOp: Option[User]): Option[String] = | |
userOp.map(_.image) | |
// can be used for _any_ F, such that F can be treated as a Functor | |
// (Option and Identity can be treated as such!) | |
def extractImageNonBreaky[F[_]: Functor](userOp: F[User]): F[String] = | |
Functor[F].map(userOp)(_.image) | |
def main(args: Array[String]): Unit = { | |
println(extractImage(getUserOp)) | |
// println(extractImage(getUserExactly)) <- this doesn't compile | |
println(extractImageNonBreaky(getUserOp)) | |
println(extractImageNonBreaky(getUserExactly)) | |
} | |
} |
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