Explore creating robust HTTP services in Scala's functional programming paradigm. Gain insights into pure vs. impure implementations, their pros and cons, and effective tool usage.

scala-platform.tar.gz

Scala-Pure

Scala-Impure

Scala-Tapir

Scala-Impure-Test

Scala-Pure-Test

Scala-Tapir-Test

Test

Scala - Run Code Widget 

Scala-Pure-copy

Scala is one of the most popular general-purpose languages that supports both object-oriented and functional programming. In this course, you will learn how to create back-end HTTP services using Scala's functional programming paradigm.

You will also learn how to develop, test, and document the service using both pure and impure ways. You will be exposed to the differences between pure and impure implementation, their respective pros and cons, and how pure implementation can be more robust in terms of performance, understandability, testability, and type safeness. 

By the end of the course, you will have a clear idea of how functional programming works in Scala and how you can use the available tools more effectively.

Pure Functional HTTP APIs in Scala

override def loadProduct(id: ProductId) =
  sql"""SELECT products.id, names.lang_code, names.name
        FROM products
        JOIN names ON products.id = names.product_id
        WHERE products.id = $id"""
    .query[(ProductId, LanguageCode, ProductName)]
    .to[Seq]
    .transact(tx) 


The `loadProduct` function simply returns all rows for a single product from the database, exactly like its [*Slick* counterpart](https://www.educative.io/courses/pure-functional-http-apis-scala/functions-for-data-access-JPBxBE360Z9). The parameter will be correctly interpolated by *Doobie* which is why we don’t need to worry about SQL injections here. We specify the type of query, instruct _Doobie_ to transform it into a sequence, and give it to the transactor. 
Please note that the code does not run at this point! While the `db.run` from *Slick* will run your code, the `transact` from *Doobie* will not. It just provides a free structure (essentially free monads) that can be interpreted later on. 

Learn how to implement functions to manipulate data and carry out main service.

Introduction

Impure Implementation

Pure Implementation

Testing Impure Services

Testing Pure Services

Benchmarks

Documentation

Epilogue

Functions for Data Access

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