FSharp List Dojo

Learn about pattern matching and recursion by creating a your own list using the discriminated union!

Installation

Install the .NET5 SDK.

Clone this git repository.

Use the following command to restore the tool.

dotnet tool restore

Getting started

Start the test runner.

dotnet watch run -p test

If you are using Visual Studio, you can also test it from Test Explorer.

At first, all tests are pending. Open the file TernaryTest.fs in the ListDojo.Test project and remove one of the prefixes p.

- ptestList "tnot properties" [
+ testList "tnot properties" [

Open the TernaryDojo.fs file in the ListDojo project and implement the tnot function.

- let tnot a = Hole?implement_tnot
+ let tnot a =
+     match a with
+     | False -> True
+     | Null -> Null
+     | True -> False

Confirm that the test passes.

Repeat this process to pass all the test cases!

1. Remove one p prefix from the test file.
2. Implement the function to be tested.
3. Confirm that the test passes.

List of materials

1. TernaryDojo
   • You will create your own tiny library for three-valued logic and learn about the basic use of discriminated unions and pattern matching.
2. OptionDojo
   • You will create your own option type, which is a type for safely handling null, and learn that discriminated unions are more useful than mere enums.
3. ListDojo
   • You will create your own list type using a discriminated union. Topics such as tail-recursion will also be covered.

Pending tests

The p stands for pending. The prefix p can be removed to include it in the test as below.

• ptestList -> testList
• ptestCase -> testCase
• ptestProperty -> testProperty