Alex Netkachov

Performance comparison of the solutions for passing byte arrays from .NET runtime to JavaScript in Blazor wasm

OverviewPassing data from and to the JavaScript environment is one of the common tasks developers need to solve while working on a WebAssembly application with Blazor. Although typical use cases are well-covered by the JSInterop classes (e.g. IJSRuntime), less common problems require putting some effort into finding the right

Functional Programming

The function Map()

Today I would like to share last of small helper functions that help write concise code. Just like Apply, it helps to avoid null-checking ifs by conditionally applying a transformation function. Differently from Apply, it returns the result of the transformation, which, apparently, is quite a frequently used pattern. Let's

The function Try()

I've recently posted about two functions that I use sometimes to write less code: Void and Apply. Today I would like to share another one of the kind, a function that helps shortening try/catch statements. Consider the typical try/catch statement: try { session.Check(); Console.Error.WiteLine("OK"); } catch

C#

The function Apply()

You may find one of these patterns while looking through C# code: byte[] Read(int length) { var data = new byte[length]; stream.Read(data, 0, length); return data; } using var rng = new RNGCryptoServiceProvider(); var salt = new byte[8]; rng.GetBytes(salt); var stdin = process.StandardInput; if (stdin != null) { stdin.Write(

C#

Void: a "magic" function

Today I would like to share with you one super-simple but powerful function that I have been using in my C# code for a while. Let me show a few code samples that have something in common: foreach (var dir in Directories()) Directory.GetParent(dir) ?? throw new SpecialException(); Action callback

C#

pwd: first week

A week ago I've published pwd on github, posted an article about it on my site, and promoted it on reddit. People generously gave it 7 stars on github and 31 upvotes on reddit (89% positive), and read the article 340 times. It could be better so if you like

C#

Story of pwd

This story is about a tool that helps me manage my encrypted files and passwords. It is a console application in C# script. Your feedback and stars are greatly appreciated.

C#

ImmutableList<T> performance

This a short story followed by simple .NET hint that can increase performance in some areas of your application in 10 times or more. In the HPS project I've implemented the same state machine simulation engine in three technologies: C++, .NET Core/C# and Go. It is a nice learning

.NET

C# 8: switch statement

At the end of January the .NET Core development team has released a new version of the .NET Core framework, .NET Core 3 preview 2. It delivers a few new C# features to developers. It is nice to see the language improving and I like all of them. But today

Debugging memory leaks in .NET applications

I personally think that using low level debuggers is a skill that any professional .NET developer must have. I just published a course on how to use LLDB for debugging memory leaks in .NET applications on macos. You can take it for £9.99 through this site*. Go to course

JavaScript

Node.js 10: Important Changes

The recent release of the node.js is a major milestone in its development. It contains many changes in the library, bugfixes and updated v8 engine. the complete changelog is here. This is a review of new features. It also inclues changes that have impact on the backward compatibility. Assert

.NET

Refactoring locks into sharing immutables

So if both Eric Lippert and Jon Skeet think lock free programming is only for people smarter than themselves, then I will humbly run away screaming from the idea immediately. – dodgy_coder – SO There is some truth in this quote. Lock-free is a quite advance subject, which includes knowing compiler

.NET

Deadlock example, .NET

It is actually a bit surprising, but many .NET developers have never had deadlocks in their code. Some very good developers may not have seen them for years. So it may be a good time to remind about them. One the common mistakes about the deadlocks is when they are

HackerRank Functional Challenges

HR F#: Functions and Fractals: Sierpinski triangles

The problem of drawing the Sierpinski triangles is considered to be advanced problem and it really is. The Sierpinski triangle is a fractal, constructed by recursively subdividing equilateral triangles into smaller equilateral triangles. If you ever played Deus Ex you may have noticed that its logo is inspired by the

HackerRank Functional Challenges

HR F#: Pascal's Triangle

The second problem from the Recursive subdomain is printing Pascal's Triangle for given n. Pascal's triangle is named after famous French mathematician from XVII century, Blaise Pascal. His findings on the properties of this numerical construction were published in this book, in 1665. Year before Great Fire of London. The

HackerRank Functional Challenges

HR F#: Computing the GCD

The greatest common divisor (or GCD) of two integers is the largest positive integer that divides two of these integers. The first of the Recursion problems on the Functional track at Hackerrank is computing the GCD using the Euclidean Algorithm. In this algorythm the largest from the pair is replaced

F#

F#: How to check that tail recursion calls are optimised

The tail recursion optimisation happens when a compiler decides that instead of performing recursive function call (and add new entry to the execution stack) it is possible to use loop-like approach and just jump to the beginning of the function. Typically it happens when the compiler is smart, the tail

F#

Quickstart WPF F#-only app in VSCode - Part 3

How to quickly create WPF F# project was shown in the first part. FsXaml and paket was added in the second part. This part will go reactive: add ReactiveUI and show how to update the view model asynchronously from F#. This part starts where the second part ends, from the

F#

Quickstart WPF F#-only app in VSCode - Part 2

The first part shown how to create a WPF F# project with simple window and its view model, build this project and run it. Now lets add FsXaml using packet, use it to create types from XAML and create user control. All by directly modifying project files and run commands

F#

Quickstart WPF F#-only app in VSCode

Quickstart WPF F# project

Quiz

The Oxford Green Belt Way problem

Here is a problem for you to test your programming skills. The Oxford Green Belt Way is a 50-mile circular walk around the city. It goes through the beautiful countryside, quiet fields and friendly villages. The group of international studens on their trip to Oxford wanted to walk entire path

HackerRank Functional Challenges

HR F#: Compute the Area of a Polygon

This is the last from the introductional problems in the Functional Programming domain on Hackerrank. This also might be most complicated among the introductionary problems: You are given the cartesian coordinates of a set of points in a 2D plane. When traversed sequentially, these points form a Polygon, P, which

HackerRank Functional Challenges

HR F#: Compute the Perimeter of a Polygon

The problem of computing perimeter of the polygon is one of the easy problems, but it requires a bit more programming. You are given the cartesian coordinates of a set of points in a 2D plane. When traversed sequentially, these points form a Polygon, P, which is not self-intersecting. Compute

HackerRank Functional Challenges

HR F#: Functions or Not?

The Functions or Not? problem is defined as follows: You are given a set of unique (x, y) ordered pairs constituting a relation. For each of these relations, identify whether they may possibly represent a valid function or not. On a new line for each test case, print YES if

HackerRank Functional Challenges

HR F#: Lambda Calculus - Evaluating Expressions #5

This is even more simple than the previous one. Compute the value of λx.λy.y. The answer is 0. See the same Church numerals table.