bencope.land

Mapping Database Values to Discriminated Unions for Domain-Driven Design Using Dapper

Let's explore two strengths of F# and their application in a typical enterprise app, using an example that is relevant to any subscription-based service - working with a user's subscription status in both the code and the database. The first strength is it's focus on the domain, and being able

F#

Composable Database Connection Middleware with Giraffe

If someone is new to Giraffe and approaching it with familiarity of the built-in .NET server utilities, then utilizing the compose combinator ( >=>) may take some getting used to. This post will explore using the compose combinator through utilizing it to supply http route handlers with a database connection. We will

ruminations

Abstraction

💡My thinking around this topic is influenced by Eric Normand's Lispcast episode on abstraction. Check it out, and his podcast. Abstraction is a common topic in programming discussions. You hear a lot about the right abstraction, the wrong abstraction; this level of abstraction or that level; leaky ones, bad ones,

F#

Domain-Driven Microservices with F#

It is well-known, or at least well-documented, that F# is an excellent language for doing type-driven development using domain driven design, although it may be less well known that F# is an excellent language for microservices. Indeed, microservices benefit greatly from F#'s typesystem - making it easy to focus

game development

Godot 4 and F#

Update: After beginning to make a game, it turned out not to be as straightfoward as this post implies. Primarily because Godot 4 requires that the C# class be a partial class extending the corresponding Godot entity. F# doesn't have a direct translation of partial classes as far as I

F#

Flutter State in F# with Fable and Redux

Fable 4.0 is on the horizon 🎉 and with it comes the ability to compile F# code to Dart. Although Fable 4 is still pre-release, the Dart compilation works great - so great that I was able to migrate the entirety of my Redux state management in a Flutter app

F#

Function Composition vs Pipelines

A composed function can be thought of as being more generalized than a pipeline, as a pipeline needs a value to start with while a composed function receives an argrument directly. let clickHandler (value: string) = value |> parse |> sanitize |> serialize |> sendPayload The function above takes an argument, then passes that argument

godot

.NET 6 in Godot 4 Alpha

It looks like the Godot 4 alpha will be getting .NET 6 soon, according to this recent news. This is pretty exciting. I look forward to trying it out and may end up doing a guide on setting up F# in Godot 4. I'm particularly interested to see how well

F#

Generate Signed S3 URL in F#

If you have a single page application, you may be wanting to upload files directly to S3 from the browser rather than using your own server side application as a middle man between the two. In F# this can be done with the Amazon S3 package Via dotnet cli: dotnet

functional programming

Function Application

Consider this function: let makeName (firstName: string) (lastName: string) = $"{firstName} {lastName}" Let's apply it different ways with and without pipes, and with and without partial application. Application without pipeline: let name = makeName "Bob" "Vila" Partial application without pipeline: let applyLastName = "Bob" let name = applyLastName "Vila" Partial application with pipeline: let

F#

.NET 6 Minimal API with F# and Giraffe

Here's my setup for an F# .NET 6 minimal API. Start by opening up the main modules we'll be using in Startup.fs (or Program.fs as I tend to name it). open System open System.Text open Dapper open Microsoft.AspNetCore.Builder open Microsoft.AspNetCore.Hosting open Microsoft.AspNetCore.

reactive programming

Reactive Programming - Tower Defense for Data

Following a reactive approach to development is like setting up defenses in a tower defense game. You set up your pipeline of operators, each with its own skill and its own preferred target - and that’s it. Allow the application to send in the events and watch the operators

react

RxJS for Functional State Management

Since it is bundled with Angular, RxJS does not tend to get much attention as a means to have state in a functional React application. However, RxJS is a powerful way to have state with little boilerplate and high resilience. It is light in boilerplate because it can achieve immutable,

functional programming

Isolating Unused, Nil Expressions in React

A functional-first approach to programming discourages a number of typical JavaScript practices, including some practices that are even typical for React. In particular, React conventions nudge us towards having unused expressions, and to have expressions that are nil (undefined or null) with its useEffect hook. Let's consider how to isolate

functional programming

Lambda Calculus and Arguments

Functions in the lambda calculus are always unary - they only take one argument. Functional programming is based on the lambda calculus, and it is useful to learn to appreciate unary functions. One useful way to train your brain to think functionally is, when you find yourself writing an n-ary

F#

Type-safe JavaScript Development with F# and Fable

F# is a suitable alternative to TypeScript for writing a JavaScript application with type-safety. But you also get the additional benefits of F#'s powerful type inference. TypeScript interface Person { firstName: string lastName: string } let people: Person[] = [ { firstName: 'John', lastName: 'Doe' }, { firstName: 'Jane', lastName: 'Doe' }, ] let names = people.map(({ firstName,

functional programming

FP Lint

ESLint can help you enforce functional-first standards. Below is a functional eslint setup I like, followed by some explaination. { "root": true, "parser": "@typescript-eslint/parser", "plugins": [ "@typescript-eslint", "fp", "prefer-let" ], "extends": [ "airbnb", "plugin:fp/recommended", "plugin:@typescript-eslint/eslint-recommended", "plugin:@typescript-eslint/recommended" ], "rules": { "semi": ["error", "never"], "prefer-const": "off", "f

game development

GetNode()

GDScript has a convenient shortcut for grabbing a child node reference within a script. For example, grabbing an AnimatedSprite and setting it to play a certain animation can be done with $AnimatedSprite.animation = "animation name". Getting a node in C# and F# is a bit more verbose. In F#: let

game development

Preferring Immutability in Godot

Game engine development tends to rely on mutability, such as keeping up with an object's position on-screen. Typically, the game object is represented by a single class with a "position" property, and as the object moves around that property mutates to reflect its new value. This is fine because these

game development

Exporting Godot Variables in F#

In Godot, it's convenient to export variables so that they can be updated via the Inspector tab. Doing so in C# looks like this: using Godot; public class Player : Area2D { [Export] public float Speed = 2f; public override void _Ready() {} public override void _Process(float delta) {} } Here the Speed variable is

lambda calculus

Argument Selection Function

The argument selection function λfirst.λsecond.first accepts a function as an argument and returns a function which, when given an argument, returns the first argument. // λfirst.λsecond.first const selectFirst = x => y => x const double = a => a * 2 const triple = a => a * 3 const applyDouble = selectFirst(double) const applyTriple

functional programming

Semantic Focus

In his book Stylish F#, Kit Eason describes a few unstylish pitfalls that developers may fall into. One of these pitfalls he calls lack of semantic focus. I'll describe the kind of code that isn't readable with minimum context as having poor semantic focus. In other words, relevant meaning isn't

functional programming

Functional Reactive Programming

There's something about FRP specifically that makes programming an absolute pleasure. Designing an elegant reactive application is a great feeling and opens you're mind to just how rewarding it can be to focus on decoupling. Thinking in reactive (message driven) streams has clear benefits between multiple applications, but even within

game development

Godot and F#

Over the weekend I got a game started with Godot Mono and F#. It works out pretty well, although it relies on using C# to extend types defined in F#. Out of the gate I've taken up a convention of defining a namespace just for defining a type (class) that

lambda calculus

Application Function

Function application function is represented by the term λf.λx.f x. It accepts a function as an argument and applies it to the argument of the function it returns. // λf.λx.f x let apply f x = f x let addOne c = c + 1 let applyAddOne = addOne |> apply |> (fun