foldLeft
trait Collection[A] {
def foldLeft[B](z: B)(op: (B, A) => B): B
}
foldLeft
applies, going from left to right, the binary operator op
to each element and the previous op
result.
The first time op
is applied it’s fed with the initial value z
.
On empty collections this function doesn’t apply op
and the initial value z
is directly returned.