Using `--check` gives error "todo WhileBang"

[abelbraaksma]

Issue created from fantomas-online

Code

let f() = task {
    return true
}

let g() = task {
    while! f() do printfn "testing testing"
}

Result (note: this is expected!)

let f () = task { return true }

let g () =
    task {
        while! f () do
            printfn "testing testing"
    }

Problem description

Having something like the above, actually prevents the formatting and when running:

dotnet fantomas . --check

raises the following exception:

error: Failed to format .\src\FSharp.Control.TaskSeq\TaskSeqInternal.fs: System.Exception: todo for WhileBang
  (Yes (656,20--656,44),
   App
     (Atomic, false,
      LongIdent
        (false,
         SynLongIdent ([e; MoveNextAsync], [(656,28--656,29)], [None; None]),
         None, (656,27--656,42)), Const (Unit, (656,42--656,44)),
      (656,27--656,44)),
   YieldOrReturn
     ((true, false),
      LongIdent
        (false, SynLongIdent ([e; Current], [(657,31--657,32)], [None; None]),
         None, (657,30--657,39)), (657,24--657,39)), (656,20--657,39))
   at Microsoft.FSharp.Core.PrintfModule.PrintFormatToStringThenFail@1439.Invoke(String message) in D:\a\_work\1\s\src\fsharp\FSharp.Core\printf.fs:line 1439
   at Fantomas.Core.ASTTransformer.collectComputationExpressionStatements(CreationAide creationAide, SynExpr e, FSharpFunc`2 finalContinuation) in /_//src/Fantomas.Core/ASTTransformer.fs:line 345
   at Fantomas.Core.ASTTransformer.mkExpr(CreationAide creationAide, SynExpr e) in /_//src/Fantomas.Core/ASTTransformer.fs:line 1123
   at Fantomas.Core.ASTTransformer.mkExpr(CreationAide creationAide, SynExpr e) in /_//src/Fantomas.Core/ASTTransformer.fs:line 1108
   at Fantomas.Core.ASTTransformer.mkExpr(CreationAide creationAide, SynExpr e) in /_//src/Fantomas.Core/ASTTransformer.fs:line 1384
   at Fantomas.Core.ASTTransformer.mkSynMatchClause(CreationAide creationAide, SynMatchClause _arg4) in /_//src/Fantomas.Core/ASTTransformer.fs:line 376
   at Fantomas.Core.ASTTransformer.mkExpr@1147-8.Invoke(SynMatchClause arg10@)
   at Microsoft.FSharp.Primitives.Basics.List.map[T,TResult](FSharpFunc`2 mapping, FSharpList`1 x) in D:\a\_work\1\s\src\fsharp\FSharp.Core\local.fs:line 246
   at Microsoft.FSharp.Collections.ListModule.Map[T,TResult](FSharpFunc`2 mapping, FSharpList`1 list) in D:\a\_work\1\s\src\fsharp\FSharp.Core\list.fs:line 74
   at Fantomas.Core.ASTTransformer.mkExpr(CreationAide creationAide, SynExpr e) in /_//src/Fantomas.Core/ASTTransformer.fs:line 1143
   at Fantomas.Core.ASTTransformer.collectComputationExpressionStatements(CreationAide creationAide, SynExpr e, FSharpFunc`2 finalContinuation) in /_//src/Fantomas.Core/ASTTransformer.fs:line 345
   at Fantomas.Core.ASTTransformer.mkExpr(CreationAide creationAide, SynExpr e) in /_//src/Fantomas.Core/ASTTransformer.fs:line 1123
   at Fantomas.Core.ASTTransformer.mkBinding(CreationAide creationAide, SynBinding _arg7) in /_//src/Fantomas.Core/ASTTransformer.fs:line 1810
   at Fantomas.Core.ASTTransformer.mkModuleDecl(CreationAide creationAide, SynModuleDecl decl) in /_//src/Fantomas.Core/ASTTransformer.fs:line 1971
   at Fantomas.Core.ASTTransformer.mkModuleDecls@3074-5.Invoke(FSharpList`1 nodes) in /_//src/Fantomas.Core/ASTTransformer.fs:line 3074
   at Fantomas.Core.ASTTransformer.mkModuleDecl(CreationAide creationAide, SynModuleDecl decl) in /_//src/Fantomas.Core/ASTTransformer.fs:line 1982
   at Fantomas.Core.ASTTransformer.mkModuleDecls@3074-5.Invoke(FSharpList`1 nodes) in /_//src/Fantomas.Core/ASTTransformer.fs:line 3074
   at Fantomas.Core.ASTTransformer.mkModuleOrNamespace(CreationAide creationAide, SynModuleOrNamespace mn) in /_//src/Fantomas.Core/ASTTransformer.fs:line 3139
   at Fantomas.Core.ASTTransformer.mds@3149.Invoke(SynModuleOrNamespace mn)
   at Microsoft.FSharp.Primitives.Basics.List.map[T,TResult](FSharpFunc`2 mapping, FSharpList`1 x) in D:\a\_work\1\s\src\fsharp\FSharp.Core\local.fs:line 244
   at Microsoft.FSharp.Collections.ListModule.Map[T,TResult](FSharpFunc`2 mapping, FSharpList`1 list) in D:\a\_work\1\s\src\fsharp\FSharp.Core\list.fs:line 74
   at Fantomas.Core.ASTTransformer.mkImplFile(CreationAide creationAide, ParsedImplFileInput _arg15, Range m) in /_//src/Fantomas.Core/ASTTransformer.fs:line 3149
   at Fantomas.Core.ASTTransformer.mkOak(FSharpOption`1 sourceText, ParsedInput ast) in /_//src/Fantomas.Core/ASTTransformer.fs:line 3574
   at Fantomas.Core.CodeFormatterImpl.formatAST(ParsedInput ast, FSharpOption`1 sourceText, FormatConfig config, FSharpOption`1 cursor) in /_//src/Fantomas.Core/CodeFormatterImpl.fs:line 66
   at Fantomas.Core.CodeFormatterImpl.formatDocument@89-3.Invoke(Unit unitVar) in /_//src/Fantomas.Core/CodeFormatterImpl.fs:line 89
   at Microsoft.FSharp.Control.AsyncPrimitives.CallThenInvoke[T,TResult](AsyncActivation`1 ctxt, TResult result1, FSharpFunc`2 part2) in D:\a\_work\1\s\src\fsharp\FSharp.Core\async.fs:line 446
   at Microsoft.FSharp.Control.Trampoline.Execute(FSharpFunc`2 firstAction) in D:\a\_work\1\s\src\fsharp\FSharp.Core\async.fs:line 104
.\src\FSharp.Control.TaskSeq\TaskSeqInternal.fs needs formatting

I wonder if the "todo" can be ignored somehow. It also seems like work has been done already, as the online tool shows it is formatted without error, so maybe I just have to be patient (but reporting anyway in case someone else encounters this).

Appreciate all the good work as always!!! It is also sooo much faster than, say, a year ago!

Extra information

• The formatted result breaks my code.
• The formatted result gives tool errors.
• I or my company would be willing to help fix this.
• I would like a release if this problem is solved (it breaks the pipeline)

Live example: https://github.com/fsprojects/FSharp.Control.TaskSeq/actions/runs/7256774972/job/19769562682?pr=209

[nojaf]

Hi there,

'6.2.3 does not support while!, it was introduced in https://github.com/fsprojects/fantomas/blob/main/CHANGELOG.md#630-alpha-002---2023-11-07

[abelbraaksma]

Great stuff! I missed it somehow in the changelog. I'll wait for next version :).

[dawedawe]

Great stuff! I missed it somehow in the changelog. I'll wait for next version :).

Or give the alpha a spin ;)
You will most likely find it very stable already.

[abelbraaksma]

I thought about that, but I couldn't find docs how to download the alpha in CI (i.e., dotnet tools update does not seem to pick up alpha versions, even if I specify them). @dawedawe do you know how? And/or where there's instruction to do so?

[abelbraaksma]

I would need to update these lines somehow, I guess, or the manifest file: https://github.com/fsprojects/FSharp.Control.TaskSeq/blob/b08c257e5513b9dcc700dc55740858b96f2d7570/.github/workflows/build.yaml#L6

[dawedawe]

What happens if you do a
dotnet tool update fantomas --prerelease ?
That should give you a
"version": "6.3.0-alpha-004",
inside of the manifest.

[abelbraaksma]

Ah, that "just works", awesome! (online there was the suggestion to use --version "*-alpha*" which did not work for me and I didn't look beyond that).

Thanks for the help 🙇.