What is flatMap Scala?

2020-03-07 by No Comments

What is flatMap Scala?

In Scala, flatMap() method is identical to the map() method, but the only difference is that in flatMap the inner grouping of an item is removed and a sequence is generated. It can be defined as a blend of map method and flatten method.

How does reduce work in Scala?

Scala | reduce() Function

  • The reduce() method is a higher-order function that takes all the elements in a collection (Array, List, etc) and combines them using a binary operation to produce a single value.
  • The order in which numbers are selected for operation by the reduce method is random.
  • Output :

What does => mean in Scala?

5. 140. => is syntactic sugar for creating instances of functions. Recall that every function in scala is an instance of a class. For example, the type Int => String , is equivalent to the type Function1[Int,String] i.e. a function that takes an argument of type Int and returns a String .

What is the easiest way to implement singleton in Scala?

In Scala, a singleton object can extend class and traits. In Scala, a main method is always present in singleton object. The method in the singleton object is accessed with the name of the object(just like calling static method in Java), so there is no need to create an object to access this method.

What is fold in Scala?

The fold function is applicable to both Scala’s Mutable and Immutable collection data structures. The fold method takes an associative binary operator function as parameter and will use it to collapse elements from the collection. The fold method allows you to also specify an initial value.

How do you fold Kotlin?

Kotlin Fold methods

  1. fold() This function helps to accumulate value starting with initial value, then apply operation from left to right to current accumulator value and each element.
  2. foldRight() foldRight() is the same as fold() , but works from right to left.
  3. foldIndexed()

What is Scala list?

A list is a collection which contains immutable data. List represents linked list in Scala. The Scala List class holds a sequenced, linear list of items. Lists are immutable whereas arrays are mutable in Scala. Lists represents a linked list whereas arrays are flat.

How to use foldleft method in Scala collections?

Scala Collections – FoldLeft Method 1 Syntax. The following is the syntax of fold method. Here, foldLeft method takes associative binary operator function as… 2 Usage. 3 Example. Here we’ve passed 0 as initial value to fold function and then all values are added. Save the above program in… More

Which is the second constraint of fold in Scala?

The second constraint of fold is that the start value must be neutral, i.e. it must not change the result. For example, the neutral value for an addition operation would be 0, 1 for multiplication, Nil lists, etc. Those are the basics! Have a fresh tip?

Why do you use foldleft in recursive function?

The order for traversing the elements in the collection is from left to right and hence the name foldLeft. The foldLeft method allows you to also specify an initial value. Using foldLeft is fundamental in recursive function and will help you prevent stack-overflow exceptions.

What’s the difference between fold, foldleft, and foldright?

Now, the difference between fold, foldLeft, and foldRight. The primary difference is the order in which the fold operation iterates through the collection in question. foldLeft starts on the left side—the first item—and iterates to the right; foldRight starts on the right side—the last item—and iterates to the left.