All streams

Lexical analysis is the first stage of a compilation process. It's used for getting a token sequence from source code. It gets an input character sequence and finds out what the token is in the start position, whether it's a language keyword, an identifier, a constant (also called a literal), or, maybe, some error. A lexical analyzer (also known as tokenizer) sends a stream of tokens further, into a parser, which builds an AST (abstract syntax tree).

It's possible to write a lexer from scratch, but much more convenient to use any lexer generator. If we define some parsing rules, corresponding to an input language syntax, we get a complete lexical analyzer (tokenizer), which can extract tokens from an input program text and pass them to a parser.

One of such generators is Flex. In this article, we'll examine how it works in general, and observe some nontrivial nuances of developing a lexer with Flex.

«Nothing makes you feel stupid quite like reading a scientific journal article» — writes the TV presenter and molecular biologist Adam Ruben. In a way, he's right — many of us get lost in the often confusing language of peer-reviewed papers. But the situation does not have to be hopeless. A bit of effort on the readers' part can go a long way. We looked at the techniques actual scientists use to navigate academic content.

And compiled them into this two-part guide (part 2).

If you use static analyzers, you will have, sooner or later, to address the task of making their integration into existing projects easier, where fixing all warnings on legacy code is unfeasible.

The purpose of this article is not to help with integration but rather to elaborate on the technicalities of the process: the exact implementations of warning suppression mechanisms and pros and cons of each approach.

Among the eye diseases are those that are especially dangerous. At first they are asymptomatic — nothing hurts, there are no complaints, they can “disguise” as other “mild” diseases and, most importantly, appear at any age and irrevocably “destroy” their eyesight.

Imagine if you left your left eye accidentally, but with your right, everything is “like a fog”! Read on the Internet how to help yourself or call your friends, and they — do not worry, blink. While they were waiting, it seemed that the fog was really over. This is how periods of anxiety recur, but at first there is little concern. And he (the murderer) began his insidious business. And as a rule, in both eyes, even if the second does not bother! And age is not an obstacle — children are also susceptible to this disease — 10% of children are blind from glaucoma.

Glaucoma is quite common in all countries — in 15% of cases of blindness, it is she who is the cause. This puts her in second place to the causes of incurable blindness!

And all is why — because the human brain very well «replaces» the dips in the field of view, if they arise gradually, adapt, and only when 30-40% of the optic nerve the feeling of «fog» begins. And all — hello, lost non-renewable!

This is a fourth article in the series of works (see also first one, second one, and third one) describing Machine Learning system based on Lattice Theory named 'VKF-system'. The program uses Markov chain algorithms to generate causes of the target property through computing random subset of similarities between some subsets of training objects. This article describes bitset representations of objects to compute these similarities as bit-wise multiplications of corresponding encodings. Objects with discrete attributes require some technique from Formal Concept Analysis. The case of objects with continuous attributes asks for logistic regression, entropy-based separation of their ranges into subintervals, and a presentation corresponding to the convex envelope for subintervals those similarity is computed.

The IT job market is going global, no doubt about it. Working remote for foreign companies or using an occupation overseas as a springboard for relocating is becoming common career trajectories among tech people, and that’s pretty great. However, while we’re rejoicing about the new opportunities, let’s not forget about the growing pains that go hand in hand. One of the most glaring issues international teams run into is that wildly different backgrounds give people wildly different expectations about what employment process, teamwork and professional relationships should look like.

These issues often come up right from the start of job seeking process. When employer and candidate have a cultural divide between them, the communication becomes hindered. And given that initial communication happens in the rigid, standardized form of e-mailed CVs, this can seriously impact the outcome.

There is a way...

Hello, Habr. I've been watching IT market for a long time. But i'd never written anything. That's the first part of my first article, so please don't hate it too much.

In this series of articles i'd like to share my experience of finding, teaching and integrating interns and juniors in a product team. (Don't confuse them with freelance teams or something like that).

I'd like to point out that everything you'll be reading in my articles represents my personal opinion. Yes, it has sound foundation in years of experience. But i won't say my experience is exclusive and therefore, the only right way to do things is to do it as i say.



In this part we'll see two sides of one entity. That, in turn, will help you to determine what kind of people you want for your team.

Let's look closer on the two basic scenarios:

One of our previous articles featured an overview of our photonics department students’ work lives. Today we’re going to expand on this topic by looking at four related MA programs: “Light Guide Photonics and Programmable Electronics”, “LED technologies and optoelectronics”, “Photonic materials” and “Laser technologies”. We sat down with some of the folks currently enrolled in these programs, as well as recent graduates, to talk about the role ITMO University played in kickstarting their careers.

Certainly this event is an example of some of the people in our longevity community coming in and just taking over a little bit of somebody else's conference to talk about longevity… but really exposing the rest of the community to it. I'm finding that at every event I go to, I'd really love to have conference presentations where I get to talk about some interesting thing about the longevity industry, because there are a lot of really interesting things going on.

But every presentation turns out to be «hey, we exist, please notice us — because this is really, really important.» Everything that you guys think that you are doing in medicine is about to be up-ended, because suddenly we're going to be actually able to stop people from getting sick and incapacitated and debilitated in old age. This is happening right now, the first rejuvenation therapies exist. But nobody notices.

The case: You fire up a professionally prepared Linux image at a cloud platform provider (Amazon, DO, Google, Azure, etc.) and it will run a kind of production level service moderately exposed to hacking attacks (non-targeted, non-advanced threats).

What would be the standard quick security related tuning to configure before you install the meat?

release: 2005, Ubuntu + CentOS (supposed to work with Amazon Linux, Fedora, Debian, RHEL as well)

When it's necessary to evaluate the orientation angles of an object you may have the question — which MEMS sensor to choose. Sensors manufacturers provide a great amount of different parameters and it may be hard to understand if the sensor fit your needs.

Brief: this article is the description of the Octave/Matlab script which allows to estimate the orientation angles evaluation errors, derived from MEMS accelerometers and magnetometers measurements. The input data for the script are datasheet parameters for the sensors. Article can be useful for those who start using MEMS sensors in their devices. You can find the project on GitHub.

The flashcard method, also known as the Leitner system, has been around for over 40 years. This versatile learning approach helps students save time and process information. Let’s look at what makes it work.

Memory has been studied for dozens of years, yet common myths surrounding it are refusing to die out.

Let’s talk about photographic memory, and how made-up memories influence our lives.

Recently DeepCode, which is a static analyzer based on machine learning, began to support checking of C and C++ projects. And now we can find out the differences between the results of the classic and the machine-learning static analysis.

A surprising number of programming languages were created to accomplish unusual tasks that have nothing to do with programming. These are commonly called esoteric. Today, we’re going to paint a general overview of the esolang landscape, and try to figure out why people are continuing to create them.

Every new business needs an online platform, some turf to call your own. So, you invest time and money to build it. Finally, after months of negotiations and revisions, you deploy it. At first, you’re happy, but weeks go by and your shiny new website is still not attracting customers. In an effort to protect your investment, you start spending more money on PR trying to get people to notice you. But it doesn’t work the same way it did before.

Bad news is — press release is dead. Good news — there are ways around that. Once you understand how we got here and why the old tricks don’t work anymore, you’ll be able to adjust and rise to the top.

TheKey is, as they like to call themselves, a «network of smart workspaces». But it wasn’t always this way.

^{The kitchen here is small, but cozy}

Image credit: Unsplash

What will the future bring to the programming world? Are there any specific technologies that will rise and fall? Which programming language one should learn to succeed in their career? What should a newbie programmer know and understand to build a successful career in the 2020s?

I had the opportunity to sit down and talk about these issues in greater detail with Vitaly Kukharenko, a CTO with 10+ years of experience and creator of several high load startups.

The internet is a global high-density slum. The Kowloon Walled City of our times, it is packed to brim with useless promotional content. Trying to sell a product in this environment is no easy feat.

No matter how original and well thought-out it is, it has to provide cultural value to succeed. Otherwise you become the knockoff brand. Below are three ways to quickly integrate brand’s culture into your content-marketing strategy, and what’s even more important — scale it with little to no additional resources.

Today, we’re happy to announce the Generally Available (GA) release of PowerShell 7.0! Before anything else, we’d like to thank our many, many open-source contributors for making this release possible by submitting code, tests, documentation, and issue feedback. PowerShell 7 would not have been possible without your help.

What is PowerShell 7?

For those unfamiliar, PowerShell 7 is the latest major update to PowerShell, a cross-platform (Windows, Linux, and macOS) automation tool and configuration framework optimized for dealing with structured data (e.g. JSON, CSV, XML, etc.), REST APIs, and object models. PowerShell includes a command-line shell, object-oriented scripting language, and a set of tools for executing scripts/cmdlets and managing modules.