Scala Training: 2018 Q2

Attendees:

Name	Email	Project
Paolo	antonio.mateo@47deg.com	@AntonioMateoGomez
Juan Carlos García Ruiz	jcgbuzon@gmail.com	@JCGhub
Javier Osuna Herrera	javier.osunaherrera@gmail.com	@javosuher
Carlos Gallardo Polanco	carlosgallardopolanco@gmail.com	@gpcarlos
David Corral	david.corral@uca.es	@DavidCorral94
Ana Gómez	angoglez@gmail.com	angoglez
Jose Gutiérrez	gutiory@gmail.com	@gutiory
Juan de la Cruz García	jcruzgar@gmail.com	jdlcgarcia
Daniel Peralta	dani.peralta.de@gmail.com	@DaniPeralta
Ignacio González Sainz	ignacio.glez.s@gmail.com	@ignaciogs
José Joaquín Arias Gómez-Calcerrada	tatinarias@hotmail.com	@empiremay

Welcome email:

Hi all!

If you have received this email is because you have been selected to attend the first sponsored Scala Training by 47Degrees Academy. So, congratulations for that.

As you probably know, the entire course will actually be just six intensive sessions, so we expect you all to be fully motivated and ready to learn a huge of passionating concepts.

The content:

• Mon. 28th May: Environment, SBT, Scala.
• Wed. 30th May: Scala - Stdlib.
• Fri. 1st June: FP Principles: Semigroup, Monoid, Applicative, Monad.
• Mon. 4th June: REST API - Http4s + Circe.
• Wed. 6th June: DB Doobie Postgres - Concepts. Relational DB, NoSQL.
• Fri. 8th June: Project - Testing + altogether + Deployment.

What do we expect from you guys, during this course?

• Just motivation, commitment, and happiness.

What do we expect from you to have ready next Monday?

• SBT (Scala Build Tool) installed
• IntelliJ IDEA Community installed:
• A valid GitHub account.

How is the course to work?

Well, it's our first edition and probably we will learn along with you all. We are not an actual academy, we are consultants, so we want to teach you how a real project works. That means that we won't pay attention just to the code exclusively, but also we'll focus the course on the methodology as well. If we use strict version-control procedures, English communication, agile methodologies for planning, etc. why don't to take all these valuable capabilities into account in a training?

So next Monday I will extend more information about all these details, but in summary, you will have your own repository where the advances need to be merged through Pull Request with its valid code review, we will use Slack to communicate each other (in English), etc.

That's all for now.

Day 1

Hello World in the command line

We start with the basic Scala Hello World:

sbt new scala/scala-seed.g8

We can name the app as my-tasks:

A minimal Scala project.

name [Scala Seed Project]: my-tasks

Template applied in ./my-tasks

Setting up the Git repo

After creating a new public repository in GitHub, we can:

cd my-tasks
git init
git add *
git commit -m "first commit"
git remote add origin git@github.com:<org>/<repo>.git
git push -u origin master

Commit

Run the app

Run:

sbt run

We'll have [info] Running example.Hello and hello as result.

Test the app

We can even run the tests:

sbt test
...
[info] HelloSpec:
[info] The Hello object
[info] - should say hello
[info] Run completed in 882 milliseconds.
[info] Total number of tests run: 1
[info] Suites: completed 1, aborted 0
[info] Tests: succeeded 1, failed 0, canceled 0, ignored 0, pending 0
[info] All tests passed.

Let's invite other team-mate to collaborate (and the teacher as well).

Hello World in IntelliJ

Requirements:

• Install Java 8
• Install plugin in IntelliJ: SBT

Open IntelliJ IDEA and add the project. Explain some concepts:

• Sbt shell
• Running tests in IntelliJ
• Version Control
• Add .gitignore

Issues, branches and pull-requests

• Issues
• Branches naming convention
• PR specs

Standard Library

Create new package called exercises.

Road map:

• Types: Classes, Objects, Case classes, Traits, Tuples, Literals and Option
• Collections: List, Maps, Sets, Ranges, Sequences, Array, Iterables, Traversable
• Statements: Pattern Matching, For-expression, Implicit.
• Functions: Higher Order Functions, Partially Applied Functions, Partial Functions, Infix/Postfix Operation, Byname Parameters, Repeated Params.

Types

Create a new package called types in exercises (also in test).

Classes

• Create new object called classes in exercises.types
• Create a new suite called ClassesSpec in test.exercises.types
• Commit

Objects

• Create new object called objects in exercises.types
• Create a new suite called ObjectsSpec in test.exercises.types
• Commit

Case classes

• Create new object called caseclasses in exercises.types
• Create a new suite called CaseClassesSpec in test.exercises.types
• Commit

Traits

• Create new object called traits in exercises.types
• Create a new suite called TraitsSpec in test.exercises.types
• Commit

Tuples

• Create a new suite called TuplesSpec in test.exercises.types
• Commit

Literals

• Create a new suite called LiteralsSpec in test.exercises.types
• Commit

Option

• Create new object called options in exercises.types
• Create a new suite called OptionsSpec in test.exercises.types
• Commit

Collections

Create a new package called collections in exercises (also in test).

Lists

• Create new object called lists in exercises.collections
• Create a new suite called ListsSpec in test.exercises.collections
• Commit

Maps

• Create a new suite called MapsSpec in test.exercises.collections
• Commit

Sets

• Create a new suite called SetsSpec in test.exercises.collections
• Commit

Ranges

• Create a new suite called RangesSpec in test.exercises.collections
• Commit

Sequences

• Create a new suite called SequencesSpec in test.exercises.collections
• Commit

Iterables

• Create a new suite called IterablesSpec in test.exercises.collections
• Commit

Traversables

• Create a new suite called TraversablesSpec in test.exercises.collections
• Commit

Statements

Create a new package called statements in exercises (only in test).

Pattern matching

• Create a new suite called PatternMatchingSpec in test.exercises.statements
• Commit

For expressions

• Create a new suite called ForExpressionsSpec in test.exercises.statements
• Commit

Implicits

• Create a new suite called ImplicitsSpec in test.exercises.statements
• Commit

Functions

Create a new package called functions in exercises (only in test).

High order functions

• Create a new suite called HighOrderFunctionsSpec in test.exercises.functions
• Commit

Partially applied functions

• Create a new suite called PartiallyAppliedFunctionsSpec in test.exercises.functions
• Commit

Partial functions

• Create a new suite called PartialFunctionsSpec in test.exercises.functions
• Commit

Infix prefix and postfix operators

• Create a new suite called InfixPrefixandPostfixOperatorsSpec in test.exercises.functions
• Commit

By-name parameter

• Create a new suite called ByNameParameterSpec in test.exercises.functions
• Commit

Repeated parameters

• Create new object called RepeatedParametersHelper in exercises.functions
• Create a new suite called RepeatedParametersSpec in test.exercises.functions
• Commit

Functional Programming fundamentals:

• Exposed the problem: Ignoring side effects
• Created the Maybe date type to wrap non existing values
• We need to be able to combine
  • Added the Combinator typeclass.
  • Added its instances for Int and Maybe
  • Added its implicits instances
  • And some syntax
• Exposed another problem: We need to handle the content
  • Added the Transformer typeclass.
  • Added its instances for Maybe
  • Added its implicits instances
  • And some syntax
• Exposed another problem: We need to lift values
  • Added the Lifter typeclass.
  • Added its instances for Maybe
  • Added its implicits instances
  • And some syntax
• Exposed another problem: We need to compute operations sequentially
  • Added the Flattener typeclass.
  • Added its instances for Maybe
  • Added its implicits instances
  • And some syntax
• Shown the same solution using:
  • scala.Option instead of Maybe
  • Some instead of Yes
  • None instead of No
  • cats.Semigroup instead of Combinator
  • cats.Functor instead of Transformer
  • cats.Applicative instead of Lifter
  • cats.Monad instead of Flattener

Commit

Tagless Final and Transport layer (REST API - Http4s + Circe)

• Models:

  • Task
  • User

• Algebras:

  • Tasks
  • Users

• Interpreters:

  • TasksInterpreter
  • UsersInterpreter

• Module:

  • Workflow

• Runtime:

  • Implicits

• HttpService:

  • Routes
  • Codecs
  • Server