Visual Studio Code

The recommended way to use Fantomas in Visual Studio Code is by using the Ionide plugin. Fantomas is integrated in FSAutoComplete which is the language server used by Ionide.
Make sure Ionide is set to the default formatter inside settings.json :

  "[fsharp]": {
    "editor.formatOnSave": true,
    "editor.defaultFormatter": "Ionide.Ionide-fsharp"
  }

Fantomas version detection used by Fantomas.Client

starting version 4.6

Fantomas version detection will try and find a compatible version in the following order:

1. The version of Fantomas used by your local project. This is the fantomas version displayed when you run dotnet tool list inside the project folder.
2. Your global Fantomas version. If fantomas was installed with dotnet tool install fantomas -g. You can see your global installations with dotnet tool list -g.
3. Executable named fantomas found in your PATH.