Scala, Java, Unix, MacOS tutorials (page 1)

March, 2023: I’m renaming the book to Learn Functional Programming The Fast Way!. I think this name is more reflective of the ZIO and Cats Effect libraries being easier to learn than ever before (without having to know category theory), and it’s also consistent with my other book, Learn Scala 3 The Fast Way!. (The PDF and Kindle version currently have this name, and the paperback is coming soon.)

February, 2023: Learn Functional Programming Without Fear is now one of my best-selling books on Gumroad.com (see the link below).

November, 2022: My new book, Learn Functional Programming Without Fear, is currently an Amazon Java and functional programming #1 new release. The book is now available in three formats:

NOTE: This is a chapter from my book, Learn Scala 3 The Fast Way. Due to a mistake, this lesson was not included in the book.

When you write functions, things can go wrong. In other languages you might throw exceptions or return null values, but in Scala you don’t do those things. (Technically you can, but other people won’t be happy with your code.)

Instead what we do is work with error-handling data types. To demonstrate this I’ll create a function to convert a String to an Int.

I’m currently updating my best-selling book, Functional Programming, Simplified, to cover Scala 3 and other technologies like ZIO and Cats Effect, and when that’s done, this will be the landing page for that book.

Until then, you can find the PDF for the new book that I’m creating here:

• The PDF version of
  Functional Programming, Simplified: Updated for Scala 3

And you can find the Scala 2 version of the book here:

• Functional Programming, Simplified
  (the 1st edition, for Scala 2)

I’ll update this page as I have more information.

(This is a recounting of a dream from October 1, 2016.)

We were playing at our camp when my older brother — who was standing on higher ground than I — saw something in the distance. He stood upright, then perfectly still. After a few moments he turned to me in a look of panic I had never seen before, pointed in a direction opposite from where he was looking, and screamed, “Run! Run!” I was startled at his behavior but I knew that something was very wrong, so I ran. And I ran.

I ran as fast as I could, weaving through the brush and constantly changing my course as I was chased by a white man on a dark horse. I thought I might be close to safety when I darted through some bushes, but I ran right into a creek that was too wide to jump across. As I paused for a moment to decide how to continue, the white man shot me in the back.

In intense pain and sudden shock, I stumbled forward into the creek, bent over with one hand in the creek. As I attempted to stand up and regain my balance, I was shot in the back again. This time my body flew forward towards the opposite side of the creek. I tried to control my fall but could not, and my torso slammed against the land. The right side of my face was pressed against the ground, my eyes still open. My right arm was trapped under my body, my left arm was somewhere down my left side. My legs lay in the creek’s water.

Here are two favorite quotes from Anandamayi Ma. I think almost all of this comes via Ram Dass, but at the moment I can’t remember what book I saw this in. So I assume that Ram Dass or one of his assistants spoke, wrote, or compiled almost all of the following, and I’ll link to one of his books once I can confirm this.

I’ve been slowly working on a series of new Scala programming books, and today I’m proud to announce the first of these:

Starting today you can buy the PDF version of Learn Scala 3 The Fast Way! for just ten dollars — $10 (USD) — at this Gumroad.com URL.

My book, Functional Programming, Simplified — 4.5-star rated on Amazon, their 6th-best selling book on functional programming, and 5-star rated on Gumroad.com — is currently on sale in three formats (prices shown in USD):

When I was writing my new functional programming book — Learn Functional Programming Without Fear — a few alternate titles for the book were:

• Learn Functional Programming the Fast Way!
• The Fastest Way to Learn Functional Programming
• From Object-Oriented Programming to Functional Programming
• Helping Object-Oriented Programmers Learn Functional Programming
• Functional Programming for Objected-Oriented Programmers

That’s because I found out — almost by accident — that the fastest way for object-oriented programming (OOP) developers to learn functional programming (FP) goes like this:

As a brief note today, I just released the first version of a new, free booklet that I’ve titled Learning Recursion.

Note: This tutorial is an excerpt from the Scala Cookbook, 2nd Edition.

As you can tell from one look at the Scaladoc for the collections classes, Scala has a powerful type system. However, unless you’re the creator of a library, you can go a long way in Scala without having to go too far down into the depths of Scala types. But once you start creating libraries for other users, you will need to learn them. This chapter provides recipes for the most common type-related problems you’ll encounter.

Scala’s type system uses a set of symbols to express different generic type concepts, including the concepts of bounds, variance, and constraints.