Fantomas VI

[nojaf]

Introduction

In the aftermath of "Project Dallas" some new opportunities have surfaced for Fantomas. The Oak model could have appeal in the larger F# community. And it makes it possible to expand more on Stroustrup functionality.

In order to seize all these opportunities we have decided to announce a new major release for 2023. This removes any restrictions and allows us to tune the public API to facilitate everything.

We kicked off this conversation during one of our "talk to the developers" sessions on your Discord server. We encourage you to join this server if you haven't already. Keep an eye out for events in the #announcements channel.

Goals

We would like to expose the SyntaxOak module and provide new endpoints to format an Oak and parse an Oak from a string.

Next, we wish to expand on Stroustrup functionality by introducing a bit more granularity. Currently, Stroupstrup is an all-or-nothing situation. To a limited degree, we wish to split up some of the existing functionality.

Lastly, we wish to introduce some auxiliary features that will improve your overall Fantomas experience.

Breaking changes

The Fantomas.Core API will break and the .editorconfig will no longer be compatible with the 5.x series. In practice, not that much will change. (It will really depend on your use case). We wish to keep the changes to a minimum and provide everybody with a smooth upgrade.

Proposed scope

Change

• Introduce a verbosity flag to control the console output. [Feature request] Less verbose output #2627
• Update Stroustrup style to be in sync with the style guide proposal.
• Exclude computation expression from Stroustrup. Splitting ExperimentalStroustrupStyle to separate settings #2276
• Introduce a separate setting for Stroupstrup in function applications ending with one or two collection expression arguments.
• Parallel formatting. [Feature request] Parallel formatting #2624

Deprecate

• In Update config to accept a single option for multiline_bracket_style #2658, we solidified the setting to control multiline record syntax. fsharp_multiline_block_brackets_on_same_column and fsharp_experimental_stroustrup_style would be removed. Going forward, only fsharp_multiline_bracket_style shall be accepted. Please note that fsharp_multiline_bracket_style is available from 5.2 onward. Sunset MultilineBlockBracketsOnSameColumn & ExperimentalStroustrupStyle  #2710
• Recursive flag in command line tool, we will always format recursively from now on. [Feature request] Invert --recursive flag #2768
• Remove strict mode. Remove strict mode #2798

Add

• Expose SyntaxOak API. Expose SyntaxOak API #2711
• Cursor API. When formatting source code programmatically you can insert a marker (range) and after formatting, we can tell you where that marker would be in the formatted code. This would be useful for editors to position the cursor after formatting. Cursor API #2727

Technical process

The plan is to do all the development on a separate v6 branch.
Bugfixing v5.2 would still happen on main.

//cc @dawedawe @josh-degraw @TheAngryByrd @edgarfgp

[nojaf]

V6 was released https://www.nuget.org/packages/fantomas/6.0.0!
Thanks again to everyone that was involved!