13)   What is function currying in Scala?

Currying is the technique of transforming a function that takes multiple arguments into a function that takes a single argument Many of the same techniques as language like Haskell and LISP are supported by Scala. Function currying is one of the least used and misunderstood one.

14)   What are implicit parameters in Scala?

Implicit parameter is the way that allows parameters of a method to be “found”.  It is similar to default parameters, but it has a different mechanism for finding the “default” value.  The implicit parameter is a parameter to method or constructor that is marked as implicit.  This means if a parameter value is not mentioned then the compiler will search for an “implicit” value defined within a scope.

15)   What is a closure in Scala?

A closure is a function whose return value depends on the value of the variables declared outside the function.

16)   What is Monad in Scala?

A monad is an object that wraps another object. You pass the Monad mini-programs, i.e functions, to perform the data manipulation of the underlying object, instead of manipulating the object directly.  Monad chooses how to apply the program to the underlying object.

17)   What is Scala anonymous function?

In a source code, anonymous functions are called ‘function literals’ and at run time, function literals are instantiated into objects called function values.  Scala provides a relatively easy syntax for defining anonymous functions.

18)   Explain ‘Scala higher order’ functions?

Scala allows the definition of higher order functions.  These are functions that take other functions as parameters, or whose result is a function.  In the following example, apply () function takes another function ‘f’ and a value ‘v’ and applies function to v.

Example:

When the above code is compiled and executed, it produces following result.

19)    What is the difference between var and value?

In scala, you can define a variable using either a, val or var keywords.  The difference between val and var is,  var is much like java declaration, but val is little different.  We cannot change the reference to point to another reference, once the variable is declared using val. The variable defined using var keywords are mutable and can be changed any number of times.

20)   What are option, some and none in scala?

‘Option’ is a Scala generic type that can either be ‘some’ generic value or none.  ‘Queue’ often uses it to represent primitives that may be null.