Computation Expressions Workshop

The Computations Expressions Workshop collects and presents the content of several papers and presents the material as a set of tutorials. This content is intended to be used in a workshop setting.

Setting up

The workshop uses the dotnet CLI as a base case. However, attendees may elect to use an editor of their choice, though the steps to use those tools will be omitted from the tutorials.

Install dotnet

• Install the dotnet CLI through the .NET Core SDK

NOTE: Some IDEs will also install the dotnet CLI.

git clone Workshop Repository

Clone the workshop repository so you have the materials available locally. Each tutorial is also tagged so that you can reference the finished result if you get stuck. git clone https://github.com/panesofglass/computation-expressions-workshop

Create a New Expecto Project

Now that you have the basics, you can get started by creating a new project with Expecto.

• Install the Expecto template with dotnet new -i Expecto.Template
• Create a new project with dotnet new expecto -lang fsharp

Outline

Introduction

What?

1. Computation Expressions
2. Query Expressions

Why?

1. Reduce arrowhead pattern
2. Familiar syntax, e.g. let and do with extensions: let!, do!, return, etc.
3. Language integrated queries (LINQ), e.g. query { for x in source do select x }
4. Language extensions without macros

Exercises

1. Computation Expressions: OptionBuilder
   1. Without a computation expression
   2. Return
   3. Bind
   4. Side effects and Delay
   5. Running a delayed computation
   6. do! with a unit result using Combine
   7. if ... then without an else
2. Combining Results: ChoiceBuilder
3. CEs for Compuations: StateBuilder
   1. Without a computation expression
   2. Side effects passed into a computation
   3. Differences between "container" and "computation"
4. Sequences: StackBuilder
   1. Yield = Return
   2. For = Bind
   3. Differences in Delay
5. Error Handling, Disposal, and More
   1. TryWith
   2. TryFinally
   3. Using
   4. While
   5. Quote
6. Extending Computation Expressions
   1. Method Overloads
   2. Adding Custom Extensions
7. Query Expressions
8. Embedded DSLs
   1. NuGet
   2. IL
   3. Saturn
   4. Freya

Project

Wrap up