scala _ parameter

Given that sequence, use reduceLeft to determine different properties about the collection. The following example shows how to get the sum of all the elements in the sequence:

scala> a.reduceLeft(_ + _)
res0: Int = 64

Don’t let the underscores throw you for a loop; they just stand for the two parameters that are passed into your function. You can write that code like this, if you prefer:

a.reduceLeft((x,y) => x + y)

The following examples show how to use reduceLeft to get the product of all elements in the sequence, the smallest value in the sequence, and the largest value:

scala> a.reduceLeft(_ * _)
res1: Int = 388800

scala> a.reduceLeft(_ min _)
res2: Int = 2

scala> a.reduceLeft(_ max _)
res3: Int = 20