success

Functional error handling in Scala alvin January 10, 2018 - 2:36pm

Because functional programming is like algebra, there are no null values or exceptions. But of course you can still have exceptions when you try to access servers that are down or files that are missing, so what can you do? This lesson demonstrates the techniques of functional error handling in Scala.

The beginning of a Scala “FileUtils” class

In production code I recommend that you use a good “Files” library like Apache Commons IO, but if you want to create your own Scala FileUtils class, here’s some source code that can help you get started.

First, here’s some code for the FileUtils class (an object, technically):

A worthy struggle has its own rewards

Working with yoga is often interesting. You stretch and twist and focus, trying to be very conscious of your movements, and then one day in the middle of a twisting pose you see your left foot coming out from behind your right ear. At first that’s a real surprise, a shock. You think, “Well, that can’t be my foot over there,” and then you realize it is your foot, and with that comes a strong sense of accomplishment, and maybe a little smile.

Then you do the same pose in the opposition direction, but twist and stretch as you might, your right foot doesn’t come out from behind your left ear. You know you can’t push it any more, at least not while doing the pose properly, so you realize there’s a bit of an imbalance. You accept that there’s still more work to do, but it’s a good thing, so you push on.

I think life is like that too, or can be like that. If you enjoy the struggle, if it’s a worthy struggle — a path with heart — the effort comes willingly, and with its own rewards.

How to use multiple Futures in a Scala for-comprehension

If you want to create multiple Scala Futures and merge their results together to get a result in a for comprehension, the correct approach is to (a) first create the futures, (b) merge their results in a for comprehension, then (c) extract the result using onComplete or a similar technique.

This is a page from my book, “A Survival Guide for New Consultants”

Recommended Reading

After I sold Mission Data in 2007, I also sold most of my belongings and drove to Alaska, a state I fell in love with during several vacations many years ago. As a result of that moving process, I sold over 400 books, keeping only the 100 or so “best” books that would fit in my car.

Forced to think about keeping only ~100 books, I learned that my favorite business books are:

Your own resolution to succeed is more important than any other thing alvin January 17, 2017 - 11:10am

“Always bear in mind that your own resolution to succeed is more important than any other thing.”

~ Abraham Lincoln (born in Hardin County, Kentucky)

Scala best practice: How to use the Option/Some/None pattern alvin October 19, 2016 - 9:16am
Table of Contents1 - Problem2 - Solution3 - Returning an Option from a method4 - Getting the value from an Option5 - Using Option with Scala collections6 - Using Option with other frameworks7 - Using Try, Success, and Failure8 - Using Either, Left, and Right9 - Discussion10 - Don’t use the get method with Option11 - See Also12 - The Scala Cookbook

This is an excerpt from the Scala Cookbook (partially modified for the internet). This is Recipe 20.6, “Scala best practice: How to use the Option/Some/None pattern.”

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Problem

For a variety of reasons, including removing null values from your Scala code, you want to use what I call the Option/Some/None pattern. Or, if you’re interested in a problem (exception) that occurred while processing code, you may want to return Try/Success/Failure from a method instead of Option/Some/None.