Scala Functional Programming Patterns

Infinite sequences – Scala streams

We have seen many examples of Scala's list. Lists are sequences. Moreover, lists are strict sequences. Meaning all elements of the list are constructed upfront. However, there are non-strict sequences, whose elements are constructed as needed.

A list is formed by connecting cons cells. There are two cases:

1. 1 :: Nil

   In this case, the cons cell has a value and the empty list as a tail. This list has only one element. Let's fire up the REPL and try the following snippets:

   scala> 1 :: Nil
   res2: List[Int] = List(1)
   

2. 1 :: 2 :: Nil

   Here, we have the cons cell having a value and another list as a tail:

   scala> (1 :: (2 :: Nil)).tail
   res11: List[Int] = List(2)
   

A list with three elements looks like the following:

scala> val ...