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class List[+T] {
def isEmpty: Boolean
def head: T
def tail: List[T]
def prepend [U >: T] (x: U): List[U] = new Cons(x, this)
def map[U](f: T => U): List[U] = if (isEmpty) Nil else tail.map(f).prepend(f(head))
}
object Nil extends List[Nothing] {
def isEmpty = true
def head = throw new Error
def tail = ???
}
class Cons[T](hd: T, tl: List[T]) extends List[T] {
def isEmpty = false
def head = hd
def tail = tl
}
object Inferred {
def foo[T](x: T): T = x
val x = foo(1)
val y = foo("abc")
def bar[U](xs: List[U]): List[U] = xs
val n = Nil
val nn = bar(Nil)
val ints: List[Int] = Nil prepend 1
val a = if (1 == 0) Nil else ints
val n2 = scala.collection.immutable.Nil
val ss2: scala.collection.immutable.List[String] = "abc" :: n2
val ss3 = "abc" :: n2
def cl = ((x: Int) => x + 1)
val ints2 = ints map (_ + 1)
}
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