Fantomas.FCS 5.0.0-beta-008

This is a prerelease version of Fantomas.FCS.
There is a newer version of this package available.
See the version list below for details.
dotnet add package Fantomas.FCS --version 5.0.0-beta-008
                    
NuGet\Install-Package Fantomas.FCS -Version 5.0.0-beta-008
                    
This command is intended to be used within the Package Manager Console in Visual Studio, as it uses the NuGet module's version of Install-Package.
<PackageReference Include="Fantomas.FCS" Version="5.0.0-beta-008" />
                    
For projects that support PackageReference, copy this XML node into the project file to reference the package.
<PackageVersion Include="Fantomas.FCS" Version="5.0.0-beta-008" />
                    
Directory.Packages.props
<PackageReference Include="Fantomas.FCS" />
                    
Project file
For projects that support Central Package Management (CPM), copy this XML node into the solution Directory.Packages.props file to version the package.
paket add Fantomas.FCS --version 5.0.0-beta-008
                    
#r "nuget: Fantomas.FCS, 5.0.0-beta-008"
                    
#r directive can be used in F# Interactive and Polyglot Notebooks. Copy this into the interactive tool or source code of the script to reference the package.
#:package Fantomas.FCS@5.0.0-beta-008
                    
#:package directive can be used in C# file-based apps starting in .NET 10 preview 4. Copy this into a .cs file before any lines of code to reference the package.
#addin nuget:?package=Fantomas.FCS&version=5.0.0-beta-008&prerelease
                    
Install as a Cake Addin
#tool nuget:?package=Fantomas.FCS&version=5.0.0-beta-008&prerelease
                    
Install as a Cake Tool

Fantomas

Fantomas logo

F# source code formatter, inspired by scalariform for Scala, ocp-indent for OCaml and PythonTidy for Python.

GitHub Workflow Status (event) Discord Nuget (with prereleases)

Quick install

How to use

Command line tool / API

Use this command to install Fantomas as a .NET 5 SDK global tool:

dotnet tool install -g fantomas --prerelease

For detailed guidelines, please read Fantomas: How to use.

FAKE build system

Fantomas can be easily integrated with FAKE build system.<br /> Check out the sample.

JetBrains Rider

The resharper-fsharp uses fantomas under the hood to format the source code. No need for any additional plugins.

Using the latest version inside Rider

For technical reasons Rider cannot always use the latest version of Fantomas found on NuGet. As a workaround you could install fantomas locally with dotnet tool install fantomas-tool and configure it as an External tool.

Rider external tool window

Rider action window

This will have an impact on your editing experiencing in Rider, the external change to the file by the command line application might trigger more internal logic inside Rider than necessary. It could be noticeable in regards to the default formatting experience.

Visual Studio Code

The recommended way to use Fantomas is by using the Ionide plugin. Fantomas is integrated in FSAutoComplete which is the language server used by Ionide.

Alternatively, you can install the fantomas-fmt extension.

Visual Studio

The F# Formatting extension sets up Fantomas as the default formatter for F# files, configurable from Visual Studio's options.

Visual Studio for Mac

Install fantomas locally with dotnet tool install fantomas-tool and configure it as an [External tool]

VS Mac external tool window

Online

Try the Fantomas online.

Early builds

Every once in a while an alpha or beta version is published to https://www.nuget.org/. Our previous MyGet feed is now deprecated.

Benchmarks

Some figures can be found at https://fsprojects.github.io/fantomas/ <br/> We use BenchmarkDotNet to collect data for each build on the master branch.

Purpose

This project aims at formatting F# source files based on a given configuration. Fantomas will ensure correct indentation and consistent spacing between elements in the source files. We assume that the source files are parsable by F# compiler before feeding into the tool. Fantomas follows two F# style guides: the F# code formatting guidelines from Microsoft by default and the G-Research F# code formatting guidelines via various settings.

Use cases

The project is developed with the following use cases in mind:

  • Reformatting an unfamiliar code base. It gives readability when you are not the one originally writing the code. To illustrate, the following example

     type Type
         = TyLam of Type * Type
         | TyVar of string
         | TyCon of string * Type list
         with override this.ToString () =
                 match this with
                 | TyLam (t1, t2) -> sprintf "(%O -> %O)" t1 t2
                 | TyVar a -> a
                 | TyCon (s, ts) -> s
    

    will be rewritten to

     type Type =
         | TyLam of Type * Type
         | TyVar of string
         | TyCon of string * Type list
         override this.ToString() =
             match this with
             | TyLam(t1, t2) -> sprintf "(%O -> %O)" t1 t2
             | TyVar a -> a
             | TyCon(s, ts) -> s
    
  • Converting from verbose syntax to light syntax. Feeding a source file in verbose mode, Fantomas will format it appropriately in light mode. This might be helpful for code generation since generating verbose source files is much easier. For example, this code fragment

     let Multiple9x9 () =
         for i in 1 .. 9 do
             printf "\n";
             for j in 1 .. 9 do
                 let k = i * j in
                 printf "%d x %d = %2d " i j k;
             done;
         done;;
     Multiple9x9 ();;
    

    is reformulated to

     let Multiple9x9() =
         for i in 1..9 do
             printf "\n"
             for j in 1..9 do
                 let k = i * j
                 printf "%d x %d = %2d " i j k
    
     Multiple9x9()
    
  • Formatting F# signatures, especially those generated by F# compiler and F# Interactive.

For more complex examples, please take a look at F# outputs of 20 language shootout programs and 10 CodeReview.SE source files.

Why the name "Fantomas"?

There are a few reasons to choose the name as such. First, it starts with an "F" just like many other F# projects. Second, Fantomas is my favourite character in the literature. Finally, Fantomas has the same Greek root as "phantom"; coincidentally F# ASTs and formatting rules are so mysterious to be handled correctly.

Contributing Guidelines

See the Contribution Guidelines.

Credits

We would like to gratefully thank the following persons for their contributions.

License

The library and tool are available under Apache 2.0 license. For more information see the License file.

Product Compatible and additional computed target framework versions.
.NET net5.0 was computed.  net5.0-windows was computed.  net6.0 was computed.  net6.0-android was computed.  net6.0-ios was computed.  net6.0-maccatalyst was computed.  net6.0-macos was computed.  net6.0-tvos was computed.  net6.0-windows was computed.  net7.0 was computed.  net7.0-android was computed.  net7.0-ios was computed.  net7.0-maccatalyst was computed.  net7.0-macos was computed.  net7.0-tvos was computed.  net7.0-windows was computed.  net8.0 was computed.  net8.0-android was computed.  net8.0-browser was computed.  net8.0-ios was computed.  net8.0-maccatalyst was computed.  net8.0-macos was computed.  net8.0-tvos was computed.  net8.0-windows was computed.  net9.0 was computed.  net9.0-android was computed.  net9.0-browser was computed.  net9.0-ios was computed.  net9.0-maccatalyst was computed.  net9.0-macos was computed.  net9.0-tvos was computed.  net9.0-windows was computed.  net10.0 was computed.  net10.0-android was computed.  net10.0-browser was computed.  net10.0-ios was computed.  net10.0-maccatalyst was computed.  net10.0-macos was computed.  net10.0-tvos was computed.  net10.0-windows was computed. 
.NET Core netcoreapp2.0 was computed.  netcoreapp2.1 was computed.  netcoreapp2.2 was computed.  netcoreapp3.0 was computed.  netcoreapp3.1 was computed. 
.NET Standard netstandard2.0 is compatible.  netstandard2.1 was computed. 
.NET Framework net461 was computed.  net462 was computed.  net463 was computed.  net47 was computed.  net471 was computed.  net472 was computed.  net48 was computed.  net481 was computed. 
MonoAndroid monoandroid was computed. 
MonoMac monomac was computed. 
MonoTouch monotouch was computed. 
Tizen tizen40 was computed.  tizen60 was computed. 
Xamarin.iOS xamarinios was computed. 
Xamarin.Mac xamarinmac was computed. 
Xamarin.TVOS xamarintvos was computed. 
Xamarin.WatchOS xamarinwatchos was computed. 
Compatible target framework(s)
Included target framework(s) (in package)
Learn more about Target Frameworks and .NET Standard.

NuGet packages (3)

Showing the top 3 NuGet packages that depend on Fantomas.FCS:

Package Downloads
Fantomas.Core

This library aims at formatting F# source files based on a given configuration. Fantomas will ensure correct indentation and consistent spacing between elements in the source files. Some common use cases include: (1) Reformatting a code base to conform a universal page width (2) Converting legacy code from verbose syntax to light syntax (3) Formatting auto-generated F# signatures.

WoofWare.Whippet.Fantomas

Helpers for accessing Fantomas syntax trees.

WoofWare.Expect

Snapshot/expect testing framework for F#

GitHub repositories

This package is not used by any popular GitHub repositories.

Version Downloads Last Updated
7.0.3 2,579 7/4/2025
7.0.2 819 5/28/2025
7.0.1 3,175 2/21/2025
7.0.0 1,583 1/10/2025
7.0.0-beta-001 145 12/30/2024
7.0.0-alpha-004 178 12/12/2024
7.0.0-alpha-003 160 11/29/2024
7.0.0-alpha-002 158 11/2/2024
7.0.0-alpha-001 198 9/16/2024
6.3.16 3,760 10/29/2024
6.3.15 14,669 9/14/2024
6.3.14 241 9/14/2024
6.3.13 290 9/10/2024
6.3.12 399 9/5/2024
6.3.11 839 8/16/2024
6.3.10 1,165 7/12/2024
6.3.9 8,699 6/9/2024
6.3.8 269 6/6/2024
6.3.7 790 6/1/2024
6.3.6 254 6/1/2024
6.3.5 283 5/30/2024
6.3.4 2,320 4/16/2024
6.3.3 1,122 4/12/2024
6.3.2 250 4/12/2024
6.3.1 1,698 3/30/2024
6.3.0 755 3/15/2024
6.3.0-beta-001 227 3/7/2024
6.3.0-alpha-008 192 3/1/2024
6.3.0-alpha-007 209 1/27/2024
6.3.0-alpha-006 501 1/9/2024
6.3.0-alpha-005 228 12/22/2023
6.3.0-alpha-004 215 12/6/2023
6.3.0-alpha-003 1,099 11/15/2023
6.3.0-alpha-002 243 11/7/2023
6.3.0-alpha-001 186 11/3/2023
6.2.3 1,389 11/2/2023
6.2.2 18,510 10/18/2023
6.2.1 308 9/18/2023
6.2.0 7,590 8/29/2023
6.1.3 309 8/25/2023
6.1.2 361 7/23/2023
6.1.1 22,289 6/29/2023
6.1.0 341 6/28/2023
6.1.0-alpha-006 251 6/20/2023
6.1.0-alpha-005 267 6/20/2023
6.1.0-alpha-004 241 6/19/2023
6.1.0-alpha-003 346 6/2/2023
6.1.0-alpha-002 323 5/2/2023
6.1.0-alpha-001 265 5/2/2023
6.0.8 308 6/20/2023
6.0.7 311 6/20/2023
6.0.6 312 6/19/2023
6.0.5 11,511 6/6/2023
6.0.4 335 6/2/2023
6.0.3 395 5/14/2023
6.0.2 342 5/5/2023
6.0.1 413 4/19/2023
6.0.0 912 4/13/2023
6.0.0-beta-001 471 4/5/2023
6.0.0-alpha-010 482 4/3/2023
6.0.0-alpha-009 274 3/31/2023
6.0.0-alpha-008 289 3/27/2023
6.0.0-alpha-007 271 3/27/2023
6.0.0-alpha-006 414 3/17/2023
6.0.0-alpha-005 262 2/24/2023
6.0.0-alpha-004 273 2/22/2023
6.0.0-alpha-003 265 2/4/2023
6.0.0-alpha-002 260 2/1/2023
6.0.0-alpha-001 318 1/24/2023
5.2.4 1,579 3/17/2023
5.2.3 711 3/6/2023
5.2.2 629 2/21/2023
5.2.1 8,812 2/4/2023
5.2.0 1,042 1/19/2023
5.2.0-alpha-012 383 1/14/2023
5.2.0-alpha-011 309 1/12/2023
5.2.0-alpha-010 255 12/30/2022
5.2.0-alpha-009 277 12/29/2022
5.2.0-alpha-008 295 12/28/2022
5.2.0-alpha-007 279 12/26/2022
5.2.0-alpha-006 273 12/22/2022
5.2.0-alpha-005 294 12/16/2022
5.2.0-alpha-004 297 12/8/2022
5.2.0-alpha-003 273 12/6/2022
5.2.0-alpha-002 278 12/4/2022
5.2.0-alpha-001 272 11/30/2022
5.1.5 1,659 12/22/2022
5.1.4 851 11/30/2022
5.1.3 1,055 11/14/2022
5.1.2 1,078 11/10/2022
5.1.1 827 11/7/2022
5.1.0 839 11/4/2022
5.1.0-beta-002 296 10/29/2022
5.1.0-beta-001 340 10/19/2022
5.1.0-alpha-007 304 10/14/2022
5.1.0-alpha-006 301 10/14/2022
5.1.0-alpha-005 271 10/7/2022
5.1.0-alpha-004 287 10/7/2022
5.1.0-alpha-003 289 10/2/2022
5.1.0-alpha-002 310 9/29/2022
5.1.0-alpha-001 383 9/18/2022
5.0.6 2,018 10/13/2022
5.0.5 1,002 10/7/2022
5.0.4 953 10/4/2022
5.0.3 1,017 9/29/2022
5.0.2 897 9/22/2022
5.0.1 941 9/18/2022
5.0.0 14,116 9/16/2022
5.0.0-beta-010 374 9/10/2022
5.0.0-beta-009 730 9/2/2022
5.0.0-beta-008 588 8/30/2022
5.0.0-beta-007 483 8/19/2022
5.0.0-beta-006 344 8/12/2022
5.0.0-beta-005 341 8/3/2022
5.0.0-beta-004 325 7/27/2022
5.0.0-beta-003 369 7/26/2022
5.0.0-beta-002 365 7/19/2022
5.0.0-beta-001 361 7/15/2022
5.0.0-alpha-011 384 7/8/2022
5.0.0-alpha-010 384 6/27/2022
5.0.0-alpha-009 308 6/21/2022
5.0.0-alpha-008 326 5/28/2022
5.0.0-alpha-007 459 5/16/2022
5.0.0-alpha-006 374 5/13/2022
5.0.0-alpha-005 334 5/7/2022
5.0.0-alpha-004 388 5/7/2022
5.0.0-alpha-003 316 5/6/2022

### Fixed

* * List of functions misaligned and breaks (Elmish). [#2158](https://github.com/fsprojects/fantomas/issues/2158)
* * Idempotency problem when Elmish Html. [#2195](https://github.com/fsprojects/fantomas/issues/2195)
* * Splitting list results in code that doesn't compile. [#2201](https://github.com/fsprojects/fantomas/issues/2201)
* * Idempotency problem when using a list with interpolated strings. [#2242](https://github.com/fsprojects/fantomas/issues/2242)
* * Idempotency problem when using set and spread syntax. [#2392](https://github.com/fsprojects/fantomas/issues/2392)
* * Formatting (*) returns ( * ). [#2452](https://github.com/fsprojects/fantomas/issues/2452)
* * Comment after last case of function with operator is removed.[#2454](https://github.com/fsprojects/fantomas/issues/2454)
* * Trailing whitespace in block comments should be preserved. [#2450](https://github.com/fsprojects/fantomas/issues/2450)