From idea to implementation: modifying the existing elliptic curve signature scheme to be deterministic and providing functions on it to obtain verifiable within the blockchain pseudorandom numbers.

In this post we'd like to share an interesting way of dealing with configuration of a distributed system.
The configuration is represented directly in Scala language in a type safe manner. An example implementation is described in details. Various aspects of the proposal are discussed, including influence on the overall development process.

(на русском)

Why do so many programmers hate UI work? Because it is tedious. Especially, for the Web, but other types of UI are only slightly easier. Layouts, margins, paddings — neverending stream of little tweaks to make it look OK on all sane environments, and somehow this freaking button sometimes overlaps that input field. Rrrr! And yes, it should not hang on button clicks, which means a lot of asynchronous programming, which is a nightmare.

And don’t even speak about aesthetics and usability! Choose right colours, element sizes and locations, find/draw images and put them where they fit, think about user workflows — isn’t it a designers’ or Ux specialists’ job?! Leave me alone, I’m a programmer. I work with backend layers, where everything is straightforward and linear, there are no buttloads of different environments to adjust to, and design is guided by mere logic without pesky fussing with ‘user friendliness’ and ’beauty’!

The traditional definition for the operation of exponentiation to a natural power (or a positive integer) had introduced approximately as follows:

Exponentiation is an arithmetic operation originally defined as the result of multiple multiplications a number by itself.

But the more precise formulation is still different:

Raising a number X to an integer power N is an arithmetic operation defined as the result of multiple [N by mod times] multiplications or divisions one by number X.

If you're interested in learning new languages or teaching them, then you probably know such a way as parallel reading. It helps to immerse yourself in the context, increases the vocabulary, and allows you to enjoy the learning process. When it comes to reading, you most likely want to choose your favorite author, theme, or something familiar and this is often impossible if no one has published such a variant of a parallel book. It's becoming even worse when you're learning some cool language like Hungarian or Japanese.

Today we are taking a big step forward toward breaking this situation.

We will use the lingtrain_aligner tool. It's an open-source project on Python which aims to help all the people eager to learn foreign languages. It's a part of the Lingtrain project, you can follow us on Telegram, Facebook and Instagram. Let's start!

Find the texts

At first, we should find two texts we want to align. Let's take two editions of "To Kill a Mockingbird" by Harper Lee, in Russian and the original one.

Most solutions to algorithmic problems can be grouped into a rather small number of patterns. When we start to solve some problem, we need to think about how we would classify them. For example, can we apply fast and slow аlgorithmic pattern or do we need to use cyclic sortpattern? Some of the problems have several solutions based on different patterns. In this series, we discuss the most popular algorithmic patterns that cover more than 90% of the usual problems.

It is different from High-School Algorithms 101 Course, as it is not intended to cover things like Karatsuba algorithm (fast multiplication algorithm) or prove different methods of sorting. Instead, Algorithmic Patterns focused on practical skills needed for the solution of common problems. For example, when we set up a Prometheus alert for high request latency we are dealing with Sliding Window Pattern. Or let say, we organize a team event and need to find an available time slot for every participant. At the first glance, it is not obvious that in this case, we are actually solving an algorithmic problem. Actually, during our day we usually solve a bunch of algorithmic problems without realizing that we dealing with algorithms.

The knowledge about Algorithmic Patterns helps one to classify a problem and then apply the appropriate method.

But probably most importantly learning algorithmic patterns boost general programming skills. It is especially helpful when you are debugging some production code, as it trains you to understand the execution flow.

Patterns covered so far:

Sliding Window I

Sliding Window II

Merge Intervals

Dutch National Flag

Matrix Spiral

Iterative Postorder Traversal

Bit Manipulation

Stay tuned :)

<Promo> If you interested to work as a backend engineer, there is an open position in my squad. Prior knowledge of Golang is not required. I am NOT an HR and DO NOT represent the company in any capacity. However, I can share my personal experience as a backend engineer working in the company. </Promo>

Let's consider the following problem: we have an array of integers and we need to find out the length of the smallest subarray the sum of which is no less than the target number. If we don't have such a subarray we shall return -1.

We can start with a naive approach and consider every possible subarray in the input:

Virtual reality is on the rise these days. The equipment that was previously the exclusive preserve of crazy scientists geeks with big money from the Ministry of Defense back in the The Lawnmower Man days, is currently affordable for ordinary people; those whose pockets are empty, can assemble a VR headset from cardboard and a smartphone according to many recipes.

Publish and Play

There exist two main functions of WebRTC operation on the server side in the field of streaming video: publishing and playing. In the case of publishing, the video stream is captured from the web camera and moves from the browser to the server. In the case of playing, the stream moves in the opposite direction, from the server to the browser, is decoded and played in the browser’s HTML5 <video> element on the device’s screen.

← Go to Part 1

Passing parameters to a function

When passing parameter to a function, category of a passed expression is implicitly converted to the category of function parameter: void f(TO_TYPE p); FROM_TYPE x; f(x); This implicit conversion takes place the same way as during an assignment (see "Assignment" section above) except that function definition cannot contain "auto" types.

• Create UserView
• Create NavigationView
• Create BottomBarView
• Create SwipeView
• Put all this together inside ContentView

When talking about "bad code" people almost certainly mean "complex code" among other popular problems. The thing about complexity is that it comes out of nowhere. One day you start your fairly simple project, the other day you find it in ruins. And no one knows how and when did it happen.

But, this ultimately happens for a reason! Code complexity enters your codebase in two possible ways: with big chunks and incremental additions. And people are bad at reviewing and finding both of them.