Difference between fold and foldLeft or foldRight?

Question

NOTE: I am on Scala 2.8—can that be a problem?

Why can\'t I use the fold function the same way as foldLeft or foldRight?

Answer 1

For your particular example you would code it the same way you would with foldLeft.

val ns = List(1, 2, 3, 4)
val s0 = ns.foldLeft (0) (_+_) //10
val s1 = ns.fold (0) (_+_) //10
assert(s0 == s1)