2016s

Validation with Either data type in C#

In this article we will employ a functional monadic concept Either to make validation code more expressive and easier to maintain.

Fire-and-forget in Service Fabric actors

At the recent Webscale Architecture meetup we discussed two implementations of the Actor model in the .NET ecosystem: Akka.NET and Azure Service Fabric Actors. One important discussion was around Ask vs Tell call model.

Monads explained in C#

The newer and much longer version of this article is now available: Monads explained in C# (again) It looks like there is a mandatory post that every blogger who learns functional programming should write: what a Monad is.

Building a Poker Bot: Card Recognition

This is the first part of Building a Poker Bot series where I describe my experience developing bot software for online poker rooms. I'm building the bot with .NET framework and F# language which makes the task relatively easy and very enjoyable.

Akka.NET-style actors in Service Fabric

Akka.NET and Service Fabric are the two actor frameworks that emerged in .NET world in the last year. The two implementations of actor models are quite different. These differences are multi-faceted but today I want to focus on API to define an actor and to communicate to it.

Building a Poker Bot: String and Number Recognition

This is the second part of Building a Poker Bot series where I describe my experience developing bot software to play in online poker rooms. Reading cards and other fixed images was the first step. The bot should also be able to read different text-based information from the screen.

Unit testing Dapper repositories

Dapper is a micro-ORM library which is very simple and super fast. Quite often the data access code is difficult to be unit tested. In this post, I present some ideas of testing Dapper-based database access.

Building a Poker Bot: Mouse Movements

The last step of the poker bot flow: clicking the buttons. The screen is already recognized, the hand is understood, the decisions are made and now the bot needs to execute the actions. This means clicking the right button at the poker table.

Aurelia Map Component with Leaflet

This is a short tutorial on how to create a map control in an Aurelia.js application. I am using the Leaflet library with custom tile source and I also show the way to implement your own overlay layer.

Functional Actor Patterns with Akka.NET and F#

My exploration of Actor model started with Akka.NET framework - a .NET port of JVM-based Akka. Actor programming model made a lot of sense to me, but once I started playing with it, some questions arose.

Building a Poker Bot with Akka.NET Actors

This post lays out the most exciting part of the bot. I'll compose the recognition, flow, decision and mouse clicking parts together into the bot application. The application is a console executable interacting with multiple windows of poker room software.

T-SQL MERGE statement is underrated

How many times did you write a SQL to save a row without knowing whether the same primary key already exists or not? You just get an object in your data access layer and you want to save all fields into the database.

Tweaking immutable objects with C# and Fody

Immutable data structures provide a lot of benefits to programmers, especially when representing domain value objects. Immutability is an essential part of functional programming paradigm. The concept is useful in object-oriented languages too, but you have to pay some price to get this advantage.

Dependency Inversion Implies Interfaces Are Owned by High-level Modules

Dependency Inversion is one of the five principles of widely known and acknowledged S.O.L.I.D. design guidelines. This principle is very powerful and useful when applied consistently.

Building a Poker Bot: Functional Fold as Decision Tree Pattern

This is the fifth part of Building a Poker Bot series where I describe my experience developing bot software to play in online poker rooms. I’m building the bot with .

Mocking API calls in Aurelia

Aurelia is a modern and slick single-page application framework. “Single-page application” aspect means that it’s loaded into the browser once, and then the navigation happens on the client side and all the data are loaded from a REST API endpoint.

Comparing Scala to F#

F# and Scala are quite similar languages from 10.000 feet view. Both are functional-first languages developed for the virtual machines where imperative languages dominate. C# for .NET and Java for JVM are still lingua franca, but alternatives are getting stronger.

Getting started with Azure Application Insights in Aurelia

Azure Application Insights is an analytics service to monitor live web applications, diagnose performance issues, and understand what users actually do with the app. Aurelia is a modern and slick single-page application framework.

Azure SQL Databases: Backups, Disaster Recovery, Import and Export

Azure SQL Database is a managed cloud database-as-a-service. It provides application developers with SQL Server databases which are hosted in the cloud and fully managed by Microsoft.

Leaflet plugin to render geographic corridors

Yesterday I’ve published a simple Leaflet plugin called leaflet-corridor. The plugin defines a new Leaflet primitive L.Corridor. When initialized with an array of geo points and width, it renders a polyline with width fixed in meters, not in pixels.

Event Sourcing and IO Complexity

Event Sourcing is an approach, when an append-only store is used to record the full series of events that describe actions taken on a particular domain entity.

Introducing Stream Processing in F#

The post was published for F# Advent Calendar 2016, thus the examples are themed around the Christmas gifts. This article is my naive introduction to the data processing discipline called Stream Processing.