Learning new programming languages helps in acquiring new perspectives and idioms.
Before learning Scala I was perfectly fine with C++ imperative statements, if you want to retrieve a value out of them just change a variable in the outer scope.
Continue reading “Functional statements in C++”“He Who Laughs Last Is At 300 Baud”, is possibly a long-forgotten joke, but sometimes C++ standard is like using a 300 baud modem, discovering “innovations” tens of years after other less committee-centric languages discover and apply them.
Let’s take the std::optional which tries to mimic the Option monad available in other languages. Since 1990 there has been a resurgence of functional programming languages in the mainstream – Haskell (1990), and Scala (2004) just to name two that have Option since their first version.
Continue reading “What’s wrong with you, std::optional?”In theory, practice and theory are the same, in practice they are not. So, after having read how brilliant and smart smart-types are, it is now time to have a closer look at the compiler and figure out what C++ can offer.
After my last post, I found that Smart Types are also known as Refined (or refinement) Types. And here is a notable implementation for Scala.
Simple things first, if you need a type with a bunch of possible values, don’t use int & #defines, don’t use bool either (please), use enum, or, even better enum class.
Now that we’ve done with the trivialities, let’s proceed to something more challenging – numeric types. Ideally, we want some template code that wraps the numeric type and saves us the boredom of writing all the usual +, -, *, /, ==, !=, <… operators, while letting us define the rules of the existence of the represented type.
Continue reading “As Smart as a Smart Type – Practice (C++)”Recently I listened to a “Happy Path Programming” podcast episode about Smart Types. And that inspired me for this double post. The first part (this one) is about what a smart type is and why you should employ smart types in your code. The second part (yet to come, hopefully soon) is about the troublesome way I implemented an arithmetic smart type template in C++.
Continue reading “As Smart as a Smart Type – Theory”Yesterday has been my last day at SISSPre, Alongside the excitement for starting a new job today, there is the melancholy of leaving talented professionals and good friends.
Continue reading “Thanksgiving”Maybe one of the main differences between embedded software/PC programmers and server/backend programmers is their attitude toward system resets. A server programmer will try as hard as possible to avoid any sort of system reboot since this could make a bad situation even worse. They would always strive for graceful service degradation (i.e. the system would not provide its full or top-level service) whenever forced to take action against unexpected or failing conditions.
Continue reading “Watchdogging the Watchdog”
Here we are with the fourth installment in this Scala Job Interview series. The first was on general questions, the second on Scala language, and the third on functional programming.
In this case, the Actor Model has nothing to do with the Star System 🙂 I’m not sure where the term actor in “actor model” comes from. but, quite for sure, it has nothing to do with Hollywood, but more with the idea of something that “acts”, i.e. makes actions.
In fact, the Actor in the Actor Model is a processing entity that receives and reacts to messages. More precisely an Actor can only perform computation on the receipt of a message, when message processing is done, the actor just idly waits for the next incoming message.
Continue reading “Scala Job Interview – Reactive Programming”
Welcome to the third installment of the Scala Job Interview Questions series. This time I’ll try to answer functional programming questions, likely my score will be a bit less than the first two editions (General Questions and Language Questions) because I like Functional Programming, but I’m still a traditional programmer (imperial?) who studied Algebra at high school and uni and then consider Algebra as useful (for programmers) as a doorstop in a tent.
Young and foolish I was, but who could imagine, back then that to run the dance of the bits I would ever need monoids?
Let’s not waste other time in void introduction, and start with the questions and my answers.
Continue reading “Scala Job Interview – FP questions”
This is the second installment of this series. The first post in the series gives you a bit more context. Anyway, this is my try to answer Scala Interview grade Questions I found in a blog post by Signify. You can find alternate answers here.
var, a val and def?All these keywords are for declaring something. var declares a variable, val declares a variable that cannot be re-assigned and def declares a function.
scala
var a = 3
val b = 3
def c = 3
In the above code, a is a variable as you can find in almost every language, you can increment it, re-assign it. Standard stuff.
b is a variable bound to value 3 forever? Attempting to change its value results in a compile-time error. c is a parameterless function that returns 3. Interestingly a, b and c evaluate to the integer 3. Also note that val just prevents reassignment, not value change. E.g. in the following code:
scala
class Foo {
private var a: Int = 3
def change( newA : Int ) : Unit = { a = newA }
}
val x = new Foo()
x.change(8)
There is no compile-time error because you are not changing the bound between x and the instance that references. You are just changing the instance.
Idling over Twitter I came across a post on Signify blog about a list of Scala Job Interview Questions. The post in fact referenced a GitHub repository. Now the post came with a pointer to ready-made answers, but I decided to take the exercise and try to reply myself. The intent was both to check my knowledge and to learn something new since I’m no Scala guru.
The post contained many questions, grouped by topic. So I prefer to split my answers along several posts to keep them short and manageable.
Let’s start with general questions.
Continue reading “Scala Job Interview Answers”