scala3-DependentMethodFuncTypes1.scala

// Adapted from:
// https://github.com/deanwampler/programming-scala-book-code-examples/blob/master/src/script/scala/progscala3/typesystem/deptypes/DepMethodFunc.scala

scala> trait LinkedList:
     |   type Item            // abstract type alias
     |   def head: Item
     |   def tail: Option[LinkedList]
     
scala> def head(ll: LinkedList): ll.Item = ll.head     // dependent method type for the return value.
     | val h: (ll: LinkedList) => ll.Item = _.head     // dependent function type for the return value (not supported in Scala 2)
     | def tail(ll: LinkedList): Option[LinkedList] = ll.tail   // similar...
     | val t: (ll: LinkedList) => Option[LinkedList] = _.tail   // similar...
def head(ll: LinkedList): ll.Item
val h: (ll: LinkedList) => ll.Item = Lambda$7945/0x0000000801d950d8@7e573edd
def tail(ll: LinkedList): Option[LinkedList]
val t: (ll: LinkedList) => Option[LinkedList] = Lambda$7946/0x0000000801d954a8@2a1e947a