Arkon's Scala Training

Description

Scala hands on training project. Looking to introduce new team members or anyone interested to the scala programming language and the way it's used within the ArkonData team.

You'll implement a web server exposing a GraphQL API to expose business retrieved from the INEGI's API and query them based on their location.

• Concepts
• Tools
• Libraries
• Exercises
• Basic commands
• Requirements

Concepts

• Functional Programming

• Referential transparency.

• Immutability.

• Recursion (FP).

• Basic concurrency using Scala's Future.

• Functor/Mondad (FP through cats).

• The real world/side effects using the IO Monad.

• Testing

• Conventional Commit

• Types and type clases

• Implicits

• hlists

Books

• https://underscore.io/books

Videos

• Let’s Code Real World App Using Purely Functional Techniques (in Scala) | deprecated link

Tools

• Scala
• IntelliJ (IDE)
• sbt

Libraries

• cats: Library for FP.
• cats-effect: IO Monad in Scala.
• FS2: Functional streams.
• Doobie: Functional layer for JDBC.
• Sangria: Scala library for GraphQL.
• ScalaTest: Scala testing library.
• ScalaCheck: Library for random testing of program properties inspired by QuickCheck.
• http4s: Library fot HTTP

Exercises

• Std lib
• Fp in Scala
• Cats
• Circe
• Doobie
• ScalaCheck

Basic commands

SBT console

$ sbt

Running sbt commands inside the SBT console

// sbt console
$ sbt

// Scala REPL
$ sbt console

// Compile the main module
sbt:arkon-scalatraining> compile

// Compile the test module
sbt:arkon-scalatraining> test:compile

// Run all tests
sbt:arkon-scalatraining> test

// Run a specific test
sbt:arkon-scalatraining> testOnly training.std.OptionSpec

Requirements

Implement a GraphQL API based on the given schema to expose the saved business and query them based on their location. The database to be used should be PostgreSQL with the PostGIS exitension to power the georeferenced queries. To fill the database you'll have to implement a web scrapper to retrieve data from the INEGI's DENUE API and execute the createShop mutation defined on the implemented API.

The implemented API should comply the following rules:

• On the createShop mutation
  • The activity, stratum and shopType fields should search for existing records on the Activity, Stratum and ShopType tables and insert only if there is no previous record.