Scala vals can be modified

Question

I'm starting to play with Scala, and one of the first things I read is that vals are:

variables that are assigned once and never change, and vars, variables that may change over their lifetime

But I'm curious why I can do this:

val foo = Array(1, 3 ,2)
scala.util.Sorting.quickSort(foo)

If I check the foo variable now is ordered, which means it has changed... also if I do print(foo), both have the same, so the variable is pointing to the same object (I could have thought that the variable just pointed to a new object)

Could anyone clarify?

[this](http://stackoverflow.com/a/1792207/298389) could help you — om-nom-nom, Jan 06 '12 at 16:35

score 15 · Accepted Answer · answered Jan 06 '12 at 16:36

15

The Array pointed to by the foo variable is changing, but the fact that foo points at that Array doesn't change. Try re-assigning foo and you will see what you are looking for.

answered Jan 06 '12 at 16:36

cdeszaq

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Of course, I'm not very clear today, the pointer to the object cannot change but the object's value can, so I can make a foo(0) = 5. Thanks – jasalguero Jan 06 '12 at 16:48
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@jasalguero FYI scala does provide immutable collections – Dan Burton Jan 06 '12 at 17:32

score 3 · Answer 2 · answered Jan 07 '12 at 23:56

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The problem is not with val, but with Array. Although values are unchangeable, arrays are. If you are looking to stop this, you can use a class within the package immutable.

answered Jan 07 '12 at 23:56

Ryan __________

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Scala vals can be modified

2 Answers2