optics

Author: kryptt

constructive-programming/optics.sc

@@ -0,0 +1,62 @@
+     //What could go wrong here?!/
+     type Gender = Boolean
+     type BirthDate = LocalDate
+
+     case class Person(name: String, birthDate: BirthDate, gender: Gender)
+     case class Man(name: String, birthDate: BirthDate)
+
+     val personToMan: Person => Option[Man] = _ match {
+       case Person(name, birthDate, True) => Some(Man(name, birthDate))
+       case p => None
+
+     }
+
+     val manToPerson: Man => Person = m => Person(m.name, m.birthDate, True)
+
+     val getTime: IO[LocalDate] = ???
+
+     val personAge: Person => IO[Int] = p => getTime.map(p.birthDate.yearsBetween)
+
+     val manAge_1: Man => Option[IO[Int]] = ???
+     val manAge_2: Man => IO[Int] = ???
+
+     case class Lens[S, A](get: S => A, set: A => S => S) {
+       def modify(A => A): S => S = ???
+
+       def compose[T](other: Lens[T, S]): Lens[T, A] = ???
+
+       def choice[T](other: Lens[T, A]): Lens[S \/ T, A] = ???
+
+       def split[T, B](other: Lens[T, B]): Lens[S /\ T, A /\ B] = ???
+
+     }
+
+     //What could go wrong here?!/
+     trait Functor[F[_]] {
+
+        def map[A, B](fa: F[A])(f: A => B): F[B] = ???
+ 
+      }
+
+      //What could go wrong here?!/
+     case class Const[A, B](a: A) implicit def constFunctor[AA] = new
+     Functor[Const[AA, ?]] {
+
+     def map[A, B](fa: Const[AA, A])(f: A => B): Const[AA, B] = ???
+
+   }
+
+   type TVL[S, A] = (Const[A, S], A => S) implicit def tvlFunctor[A] = new
+     Functor[TVL[?, A]] {
+
+     def map[S, T](fa: TVL[S, A])(f: S => T): TVL[T, A] = ???
+
+   } trait Lens[S, A] {
+     def apply[F[_]: Functor](A => F[A]): S => F[S]
+     def get(s: S): A = ???
+     def set(a: A, s: S): S = ???
+     def modify(A => B): Lens[S, B] = ???
+     def compose[T](other: Lens[T, S]): Lens[T, A] = ???
+     def choice[T](other: Lens[T, A]): Lens[S \/ T, A] = ???
+     def split[T, B](other: Lens[T, B]): Lens[S /\ T, A /\ B] = ???
+   }