CODEWITHSUNDEEP
scala
Joe Johnes
Joe Johnes

Reputation: 27

In scala, is there an alternative to using the :: to append to front or end of a list?

If a have a val x = List(2,3,5,8) and I want to append element 4 to the list, x::a or a::x work as expected. But is there an alternative to this notation?

Upvotes: 0

Views: 88

Answers (1)

Berthur
Berthur

Reputation: 4495

If I understood your question correctly, we have:

val x = List(2,3,5,8)
val a = 4

and you wish to append (in immutable terms) a to x.

a::x works but will return a list with 4 prepended, so not what you asked for. x::a will not work at all because, well, you can't really prepend a list to an integer.

What you can do, for example, is use the :+ method:

x :+ a  // Returns List(2, 3, 5, 8, 4)

Notice however that appending to a List requires linear time and may therefore be a bad idea, depending on your particular application. Consider using a different data structure if the performance of this operation is important. More information here.

Upvotes: 3

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