raymondtay / HandsonFP

Contains code to answers and exercises during the conduction of the functional programming class in Scala

HandsonFP

This tutorial assumes that you have some prior experience programming in Scala. This series of exercises might be a little overwhelming for the absolute beginner but once you have gained some proficiency in Scala, i am positive you would be able to follow.

Getting Started

You should be comfortable with the Linux/Unix/WinOS/macOS environment configuring it. I do not have instructions on how to leverage IDEs, so please use Google or Stackoverflow for your individual purposes.

To start from the ground up, you basically need the following:

• You would need a Oracle JDK version 1.8 to be installed on your environment.
  • Tested on JDK8, JDK11, JDK12 to be working with Scala 2.13.1
• You would need to install the Scala build tool aka sbt from here. (Note: There're
  installation instructions on each operating system like macOS, Linux/Unix, Win OS.)
• Your favourite editor (i use neovim) or IDE.
• You should not have trouble cloning this repository.

A little about me

I really enjoy Scala, Haskell and have developed some skills in functional programming. I hope to share with you my passion in functional programming and hope that you have learnt something from this.

Onward and forward !

Format of the tutorial

This tutorial is drawn from a few sources of inspiration and its based on the following approach:

• I present an introduction to each topic in the package to help develop the intuition for them.
• Exercises in the package are presented and should be attempted
• Answers revealed 1 week after presentation
• Recurse till we reach the end.

Table of contents:

The order in which we are going to proceed by working through the following exercises housed in the following packages:

• gettingstarted
• datastructures
• handlingerrors
• managing state; composing state functions
• parallelism and concurrency in Scala
• TBA

Note: All answers to the exercises will be revealed 1 class after each training.

Property-based Testing

In this repository, you will soon discover that property-based testing (in the sbt console, fire test or sbt test if you prefer to run directly from the directory) is implemented which serves two (2) purposes:

• Validating the functionality of your implementation
• Cornerstone for you to leverage on these tests to expand your own learnings

sbt:Hands-on Functional Programming in Scala> test
[info] Compiling 4 Scala sources to /Users/raymondtay/HandsonFP/answers/target/scala-2.13/test-classes ...
[info] Done compiling.
[info] + Tree.size of trees are at least zero: OK, passed 100 tests.
[info] + Tree.maximum of trees: OK, passed 100 tests.
[info] + Tree.depth of trees: OK, passed 100 tests.
[info] + Tree.`map` of trees: OK, passed 100 tests.
[info] + List.`sum` of ints: OK, passed 100 tests.
[info] + List.`product` of ints: OK, passed 100 tests.
[info] + List.`append` left-/right-identity : OK, passed 100 tests.
[info] + List.`append` general scenarios : OK, passed 100 tests.
[info] + State.`set` will always set its state w/o altering its result: OK, passed 100 tests.
[info] + State.`unit` will always return its pre-defined result: OK, passed 100 tests.
[info] + State.`flatMap` will always chain its state, optionally returning a computation on its results: OK, passed 100 tests.
[info] + State.`modify` will always replace its state, discarding its result.: OK, passed 100 tests.
[info] + State.`map2` will combine two state functions via a binary operation: OK, passed 100 tests.
[info] + State.`map` will always apply its function: OK, passed 100 tests.
[info] + HoF.findFirst - Strings: OK, passed 100 tests.
[info] + HoF.findFirst - Ints: OK, passed 100 tests.
[info] + HoF.isSorted - Ints: OK, passed 100 tests.
[info] + MyTransformation.isSorted for Strings: OK, passed 100 tests.
[info] + MyTransformation.isSorted for Ints: OK, passed 100 tests.
[info] + MyTransformation.isSorted for Double: OK, passed 100 tests.
[info] Passed: Total 20, Failed 0, Errors 0, Passed 20
[success] Total time: 4 s, completed 12 Feb, 2020 8:44:42 AM

References

• Programming in Scala (4th Edition) by Martian Odersky, Lex Spoon, Bill Venners
• Functional Programming in Scala by Paul Chiusano, Runar Bjarnason
• Learn You a Haskell for Great Good by Miran Lipovca
• Haskell In Depth by Vitaly Bragilevsky
• Real World Haskell by Bryan O'Sullivan, John Goerzen, Don Stewart
• Parallel and Concurrent Programming in Haskell by Simon Marlow
• Michael Snoyberg's series of Haskell articles on http://www.fpcomplete.com