Checking that all items in a collection match a pr

问题:

What's the most idiomatic way to test whether all items of a collection match a predicate?

Any item?

回答1:

There are built-in functions for this:

List(1,2,3,4).forall(x => x < 5)
res0: Boolean = true

for any:

List(1,2,3,4).exists(x => x > 3)
res1: Boolean = true