SAFE Stack workshop

Full stack web development in F#

by Zaid Ajaj

About Me

• Zaid Ajaj

• Originally from Iraq

• Living in the Netherlands

• Lead Developer at eSightMonitoring

• Working with C#, Javascript, F# and SQL

• Active OSS contibutor to everything F#-related

• Author of The Elmish Book

• Follow me on Twitter & Github for F# news and latest developments

Table Of Contents

• What is F#?

• Why learn and use F#?

• Getting started

• Functional thinking

• Unit testing

• Data access

• Beginning SAFE-Stack

What is F#?

• Functional-first programming language

• Part of .NET

• Based on OCaml

• Statically typed

Why learn F#?

• Focus on simplicity

• Focus on correctness

• Fully featured core library

• Powerful type-system that works for you!

• Safe by default (unless you want otherwise)

• Different way of thinking about problems

• Huge set of available libraries from .NET and F#

• Use everywhere: desktop, web backend, web frontend, mobile etc.

Getting started with F#!

• Use dotnet CLI

• F# interactive

• Use any editor: Visual Studio, VS Code or Rider

• Visual Studio + F# Interactive is a great place to learn

• Building a console application

• F# basics

Using dotnet CLI

Starting F# Interactive

dotnet fsi

Creating a new console application

dotnet new console -lang F#

Building and running the application

dotnet run

Adding nuget packages

dotnet add package [package-name]

F# Basics

• Value assignment, function declaration

• Expressions everywhere and type-inference

• Conditionals

• Lists, arrays and sequences

• The |> forward pipe operator

• Record types

• Union types

• Pattern matching

Applied Functional Programming

Demonstrating idiomatic functional code:

• Parsing strings as integers

• Modelling shapes with unions

• Recursive shapes

Unit Testing with F#:

• Using Expecto

• Building test utilities with function

• Project can be found in the repository safe-workshop-parsing

Data access with F#:

• Very simple when using Npgsql.FSharp

• Built ontop of Ngpsql

• Static SQL analysis in VS using Npgsql.FSharp.Analyzer

• Schema management with migrations out of scope, recommended to use DbUp

• Similar API for different providers

  • DustyTables for MS-SQL

  • Fumble for SQLite

  • No static analysis :(

Beginning SAFE-Stack

• Full Stack F# web development

• Backend built on AspNet Core via Giraffe and Saturn

• Frontend built on React via Feliz and Elmish

• Compiling to Javascript using Fable

• Modern intergration with the JS ecosystem

• Fable already has a large set of bindings

• Using SAFE.Simplified template

• Abstracting HTTP/JSON away with Fable.Remoting

SAFE-Stack Templates:

• SAFE-Template - Official templates comes in two flavors (minimal & default)

• SAFE.Simplified - focuses on people with dotnet background

Thanks for having me!

• See you next time.

• Questions?