Add formatting

[nojaf]

I'd like to start contributing to this repository.
It seemed like a good start to enable formatting.
I've added a --check to ensure everybody does it.

If you accept this PR, don't squash the commits otherwise the git-blame-ignore-revs-file won't be effective anymore.

[safesparrow]

Thanks for contributing!

The change looks good, I look forward to not having to think how to format the code.

Question: Does the .editorconfig provided mean that Rider's auto-format will obey exactly the same rules as Fantomas CLI?

[safesparrow]

I'm surprised that this is the G-Research convention. Does it always try to fit the record definition in one line if it's short-enough?

[nojaf]

You could put fsharp_max_record_width = 0 in your .editorconfig.
This will use the long format if the length of the record is more than 0 characters.

[safesparrow]

I ran Rider's auto-format on one of the files (Runner/Runner.fs) and it resulted in quite a few changes.
Here is my (default) formatting config:

Fantomas version is the one pulled in via dotnet tool:

Is it possible to fully align Rider? Do we need to extend .editorconfig with some extra options?

[nojaf]

Yes, this is that paint point I mentioned when using Rider.
They pass their own default values for Fantomas when you don't have them in your .editorconfig.

The command line check doesn't know about these and you get mixed results.
The full set of default values for Fantomas would be:

indent_size=4
max_line_length=120
end_of_line=crlf
insert_final_newline=true
fsharp_space_before_parameter=true
fsharp_space_before_lowercase_invocation=true
fsharp_space_before_uppercase_invocation=false
fsharp_space_before_class_constructor=false
fsharp_space_before_member=false
fsharp_space_before_colon=false
fsharp_space_after_comma=true
fsharp_space_before_semicolon=false
fsharp_space_after_semicolon=true
fsharp_space_around_delimiter=true
fsharp_max_if_then_short_width=0
fsharp_max_if_then_else_short_width=60
fsharp_max_infix_operator_expression=80
fsharp_max_record_width=40
fsharp_max_record_number_of_items=1
fsharp_record_multiline_formatter=character_width
fsharp_max_array_or_list_width=80
fsharp_max_array_or_list_number_of_items=1
fsharp_array_or_list_multiline_formatter=character_width
fsharp_max_value_binding_width=80
fsharp_max_function_binding_width=40
fsharp_max_dot_get_expression_width=80
fsharp_multiline_block_brackets_on_same_column=false
fsharp_newline_between_type_definition_and_members=true
fsharp_align_function_signature_to_indentation=false
fsharp_alternative_long_member_definitions=false
fsharp_multi_line_lambda_closing_newline=false
fsharp_experimental_keep_indent_in_branch=false
fsharp_blank_lines_around_nested_multiline_expressions=true
fsharp_bar_before_discriminated_union_declaration=false
fsharp_experimental_stroustrup_style=false
fsharp_keep_max_number_of_blank_lines=100
fsharp_strict_mode=false

Even though the command line doesn't need any of those, to get the same result out of Rider you would need to add some of these.

[safesparrow]

Thanks @nojaf 👍