This topic is about Scala Collections – Fold Method.
fold() method is a member of TraversableOnce trait, it is used to collapse elements of collections.
Syntax
The following is the syntax of fold method.
def fold[A1 >: A](z: A1)(op: (A1, A1) ? A1): A1
Here, fold method takes associative binary operator function as a parameter. This method returns the result as value. It considers first input as initial value and second input as a function (which takes accumulated value and current item as input).
Usage
Below is an example program of showing how to use fold method −
Example
object Demo {
def main(args: Array[String]) = {
val list = List(1, 2, 3 ,4)
//apply operation to get sum of all elements of the list
val result = list.fold(0)(_ + _)
//print result
println(result)
}
}
Here we’ve passed 0 as initial value to fold function and then all values are added. Save the above program in Demo.scala. The following commands are used to compile and execute this program.
Command
\>scalac Demo.scala \>scala Demo
Output
10
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