CODEWITHSUNDEEP
scalacollectionsfunctional-programmingscala-collections
user1026498
user1026498

Reputation: 443

Scala List building

I am having trouble understanding Scala lists. I just want to create a list of lists: List(list(1,2), List(3,4)) In the REPL I am trying:

val list= List()
val lt = List(1,2)
val ls = List(3,4)
list::lt resolves to - res0: List[Any] = List(List(), 1, 2) 
list::ls resolves to - res1: List[Any] = List(List(), 3, 4)

I'm coming from java and have never programmed functionally. I am just not getting it.

Thanks for any help!!

Upvotes: 1

Views: 74

Answers (1)

som-snytt
som-snytt

Reputation: 39587

You'll want to read the book, where it explains that cons :: prepends to the thing on the right.

one way to initialize new lists is to string together elements with the cons operator, with Nil as the last element.

scala> List(1,2) :: Nil
res1: List[List[Int]] = List(List(1, 2))

The book also explains about operators ending in a colon.

If you stick a List[Nothing] on the front of a List[Int], you get the List[Any] you witnessed.

Upvotes: 6

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