A presentation at DDD South West 2019 in in Bristol, UK by Stuart Lang
Build an ASP.NET Core Web App with F#? You must be having a Giraffe! https://stu.dev
Hello! https://stu.dev https://stu.dev 2
What I’ll cover ◉ ◉ ◉ ◉ ◉ https://stu.dev What is Giraffe? Where does it fit in? Why F#? How does Giraffe work? Questions 3
1 https://stu.dev What is it? 4
5 A functional ASP.NET Core micro web framework for building rich web applications. “ https://stu.dev
Idiomatic C# https://stu.dev Idiomatic F# 6
(Saturn) https://stu.dev 7
ThoughtWorks Technology Radar https://stu.dev 8
1 https://stu.dev Why F#? 9
Why F#? Like C# it’s ◉ General Purpose, so can be used for ○ ○ ○ ○ ○ ○ https://stu.dev Web apps Microservices Cloud apps Xamarin apps Desktop … 10
Why F#? Like C# it’s ◉ Multi-paradigm ○ Functional first ○ Imperative and mutability when you need it ○ OO when you need it https://stu.dev 11
Why F#? Like C# it’s ◉ Out-of-the-box with .NET Core SDK ○ It’s there, and project templates https://stu.dev 12
Why F#? Like C# it’s ◉ Got great tooling support https://stu.dev 13
Why F#? You don’t need to ask your boss Stu says it’s fine! https://stu.dev 14
Why F#? F# is concise and low ceremony https://stu.dev 15
Why F#? Correctness ◉ Solves the null problem ◉ Immutable by default ◉ Make invalidate state impossible to represent https://stu.dev 16
Why F#? - Forward Pipe Functions and values can have any name you chose https://stu.dev 17
Why F#? - Records https://stu.dev 18
Why F#? - Discriminated Unions Credit: Luke Merrett https://stu.dev 19
Why F#? It’s great for domain modelling 20
1 https://stu.dev How does it work? 21
An example Giraffe app (source) https://stu.dev 22
Let’s model it! type HttpServer = https://stu.dev 23
Let’s model it! type HttpHandler = https://stu.dev 24
Let’s model it! https://stu.dev 25
Let’s model it! Taking inspiration from Suave… https://stu.dev 26
Let’s model it! type HttpHandler = https://stu.dev 27
Let’s model it! https://stu.dev 28
Let’s model it! type HttpHandler = https://stu.dev 29
Let’s model it! (compose / >=>) https://stu.dev 30
Let’s model it! https://stu.dev 31
Let’s model it! https://stu.dev 32
Let’s model it! https://stu.dev 33
Let’s model it! https://stu.dev 34
Let’s model it! (btw, this is just the same as:) https://stu.dev 35
Let’s model it! type HttpHandler = https://stu.dev 36
Let’s model it! https://stu.dev 37
Let’s model it! https://stu.dev 38
Let’s model it! But it could be better… https://medium.com/@gerardtoconnor/carry-on-continuation -over-binding-pipelines-for-functional-web-58bd7e6ea009 https://stu.dev 39
Let’s model it! type HttpFunc = type HttpHandler = https://stu.dev 40
Let’s model it! https://stu.dev 41
Let’s model it! type HttpFunc = type HttpHandler = https://stu.dev 42
Let’s model it! Familiar… ASP.NET Core Middleware https://stu.dev 43
Performance! TechEmpower Benchmarks https://stu.dev 44
Performance! TechEmpower Benchmarks https://stu.dev 45
It’s a fullstack framework! ◉ View engines ○ DotLiquid ○ Razor ○ GiraffeViewEngine (HTML DSL) ◉ Much more https://stu.dev 46
A simple app https://stu.dev 47
Resources ◉ Documentation ◉ Dustin Moris Gorski - Functional ASP.NET Core ◉ Zaid Ajaj Giraffe helpers https://stu.dev 48
We use it! ◉ sse.co.uk https://stu.dev 49
What’s missing? ◉ Swagger / OpenAPI https://stu.dev 50
Summary ◉ Giraffe is middleware on steroids! ◉ F# is great https://stu.dev 51
Thanks! ◉ Find me at: stu.dev https://stu.dev 52
In this talk, I will share with you what Giraffe is, how it works, what a Giraffe application looks like, and a look at some of the features.
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