1.
Presented By:
Humera Ahmad
Kuldeepak Gupta
Software Consultant
Knoldus Inc
Deep Dive into Monads
and Cats Lib

2.
Lack of etiquette and manners is a huge turn off.
KnolX Etiquettes
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time and conclude on time!
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session in case you need to attend
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Avoid Disturbance
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the session.

3.
Our Agenda
Introduction to Scala Cats
01
Type Class Components
02
Semigroups
03
Monoids
04
05 Monads

4.
Introduction to
Scala Cats

5.
LEARN NOW
c
Scala Cats
● A Library that provides the abstraction
for functional programming in scala.
● Goal is to provide a foundation for an
ecosystem of pure, typeful libraries to
support functional programming in
Scala applications.
● The name is a playful shortening of the
term category, from “Category Theory”

6.
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● Fast - It provides lightweight fibers for
asynchronous, highly concurrent applications
● Reliable - Keeps your application up and
running under high resource contention.
● Ecosystem - Provides a thriving ecosystem of
streaming frameworks, database layers, HTTP
Servers and much more!
● Community - Cats Effect is OS software
maintained by Typelevel community.

7.
Type Class
Components

8.
Type Class Components
Type Class Type Class Use Type Class Instance
Interface Objects Interface Syntax

9.
LEARN NOW
c
Type Class
● Type classes are a pattern in
programming originating in HASKELL.
● The intent is to extend the existing
libraries with new functionality.
● Also, don’t need to use traditional
inheritance, and also without altering
the original library source code.
● API represented by trait with atleast
one type parameter.

10.
LEARN NOW
c
Type Class
Instances
● Used to provide an implementation of
the type class for a specific type.
● Instances are defined by creating
concrete implementations of the type
class and tagging them with the implicit
keywords.
● These instances are also known as
implicit values.

11.
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c
Type Class
Use
● Simplest way of creating an interface
that uses a type class is to place in a
singleton object.
○ To use the object, just import any type
class instance.
● Alternative to Singleton objects, use
extension methods to extend existing
types with interface methods
○ To use syntax, import it alongside the
instances for the types needed.

12.
Semigroups

13.
LEARN NOW
c
Semigroups
● In mathematics, It is an algebraic
structure consisting of a set together
with an associative binary operation
● A generic type with a binary operation
and satisfying associativity.
Example
trait Semigroup[T] {
def combine(x: T, y: T): T
}

14.
Monoids

15.
LEARN NOW
c
Monoids
● An algebraic structure with a single
associative binary operation and an
identity element.
● Let’s make it easier: It allows us to add
or combine values. Working with lists,
adding values or concatenating strings.
Example
trait Monoid[T] extends Semigroup[T] {
def empty: T
}

16.
Monads

17.
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c
Monad
● Common abstraction in Scala
● An abstraction that allows us to
represent sequences of operations
within the context such as a List, an
Option, Future, etc.
● Definition of Monad:
trait Monad[F[_]] {
def unit[A](val: A): F[A]
def flatMap[A, B](value: F[A])(func: A => F[B]): F[B]
}

18.
Demonstration

19.
Thank You !