Stroustrup: Type alias for anonymous record type

[nojaf]

Issue created from fantomas-online

Code

type Props =
  {| SessionId: string
     Dispatch: Msg -> unit
     OnTextareaFocus: unit -> unit |}

type Props =
  { SessionId: string
    Dispatch: Msg -> unit
    OnTextareaFocus: unit -> unit }

Result

type Props =
    {| SessionId: string
       Dispatch: Msg -> unit
       OnTextareaFocus: unit -> unit |}

type Props = {
    SessionId: string
    Dispatch: Msg -> unit
    OnTextareaFocus: unit -> unit
}

Problem description

I propose to include this case as part of the scope of #1408
Expected result:

type Props = {| 
    SessionId: string
    Dispatch: Msg -> unit
    OnTextareaFocus: unit -> unit 
|}

To solve this, fsharp_multiline_block_brackets_on_same_column would need to respected first.

Extra information

• The formatted result breaks by code.
• The formatted result gives compiler warnings.
• I or my company would be willing to help fix this.

Options

Fantomas master branch at 2022-04-01T14:31:49Z - b6828ff

    { config with
                MultilineBlockBracketsOnSameColumn = true
                Ragnarok = true }

_{Did you know that you can ignore files when formatting from fantomas-tool or the FAKE targets by using a .fantomasignore file?}

[nojaf]

Hi @josh-degraw, could I inspire you to take a peek at this as well?

type Props =
  {| SessionId: string
     Dispatch: Msg -> unit
     OnTextareaFocus: unit -> unit |}

Is actually a TypeDefnAbbrevNode where the type would be TypeAnonRecordNode.

As the aligned version is working these days, it would be a matter of adding more logic before the new line between the header and body of the type definition.

fantomas/src/Fantomas.Core/CodePrinter.fs

Lines 3351 to 3366 in 7c3b2e9

	| TypeDefn.Abbrev node ->
	let hasMembers = List.isNotEmpty members
	header
	+> sepSpaceOrIndentAndNlnIfExpressionExceedsPageWidth (genType node.Type)
	+> onlyIf
	hasMembers
	(optSingle
	(fun withNode ->
	indentSepNlnUnindent (
	genSingleTextNode withNode
	+> onlyIfCtx (fun ctx -> ctx.Config.NewlineBetweenTypeDefinitionAndMembers) sepNln
	+> indentSepNlnUnindent (genMemberDefnList members)
	))
	typeName.WithKeyword)
	|> genNode node

Most likely quite specific logic is only relevant to this case.
Things like:

• config is stroustrup
• type is anon record type
• no members
• the body is multiline

[josh-degraw]

Yep this was next on my list to look into! I'll give it a try today if I get a chance.