Initial support of SynExpr.DotLambda.

Directory.Build.props

@@ -39,7 +39,8 @@ Some common use cases include:
 
     <!-- Versions -->
     <PropertyGroup>
-        <FCSCommitHash>9c8b4192966e6554adc5dcc8973f2a23c8fa2722</FCSCommitHash>
+        <FCSRepo>tboby/fsharp-1</FCSRepo>
+        <FCSCommitHash>33aeee8b463b649e5caed356aab6d4f2bf6b73bf</FCSCommitHash>
         <StreamJsonRpcVersion>2.8.28</StreamJsonRpcVersion>
         <FSharpCoreVersion>6.0.1</FSharpCoreVersion>
     </PropertyGroup>

build.fsx

@@ -193,6 +193,10 @@ let fsharpCompilerHash =
     let xDoc = XElement.Load(__SOURCE_DIRECTORY__ </> "Directory.Build.props")
     xDoc.XPathSelectElements("//FCSCommitHash") |> Seq.head |> (fun xe -> xe.Value)
 
+let fcsRepo =
+    let xDoc = XElement.Load(__SOURCE_DIRECTORY__ </> "Directory.Build.props")
+    xDoc.XPathSelectElements("//FCSRepo") |> Seq.head |> (fun xe -> xe.Value)
+
 let updateFileRaw (file: FileInfo) =
     let lines = File.ReadAllLines file.FullName
     let updatedLines =
@@ -213,8 +217,7 @@ let downloadCompilerFile commitHash relativePath =
             file.Directory.Create()
             let fs = file.Create()
             let fileName = Path.GetFileName(relativePath)
-            let url =
-                $"https://raw.githubusercontent.com/dotnet/fsharp/{commitHash}/{relativePath}"
+            let url = $"https://raw.githubusercontent.com/{fcsRepo}/{commitHash}/{relativePath}"
             let! response =
                 Http.AsyncRequestStream(
                     url,

src/Fantomas.Core.Tests/DotLambdaTests.fs

@@ -0,0 +1,50 @@
+module Fantomas.Core.Tests.DotLambdaTests
+
+open NUnit.Framework
+open FsUnit
+open Fantomas.Core.Tests.TestHelpers
+
+[<Test>]
+let ``function call`` () =
+    formatSourceString
+        false
+        """
+let x = "a" |> _.ToString ()
+"""
+        config
+    |> prepend newline
+    |> should
+        equal
+        """
+let x = "a" |> _.ToString()
+"""
+
+[<Test>]
+let ``property call`` () =
+    formatSourceString
+        false
+        """
+let x = "a" |> _.Length
+"""
+        config
+    |> prepend newline
+    |> should
+        equal
+        """
+let x = "a" |> _.Length
+"""
+
+[<Test>]
+let ``property of function invocation`` () =
+    formatSourceString
+        false
+        """
+let c = _.ToString().Length
+"""
+        config
+    |> prepend newline
+    |> should
+        equal
+        """
+let c = _.ToString ().Length
+"""

src/Fantomas.Core.Tests/Fantomas.Core.Tests.fsproj

@@ -128,6 +128,7 @@
     <Compile Include="CursorTests.fs" />
     <Compile Include="MultipleDefineCombinationsTests.fs" />
     <Compile Include="ParenthesesTests.fs" />
+    <Compile Include="DotLambdaTests.fs" />
   </ItemGroup>
   <ItemGroup>
     <ProjectReference Include="..\Fantomas.Core\Fantomas.Core.fsproj" />

src/Fantomas.Core/ASTTransformer.fs

@@ -1557,6 +1557,12 @@ let mkExpr (creationAide: CreationAide) (e: SynExpr) : Expr =
         |> Expr.IndexRange
     | SynExpr.IndexFromEnd(e, _) -> ExprIndexFromEndNode(mkExpr creationAide e, exprRange) |> Expr.IndexFromEnd
     | SynExpr.Typar(typar, _) -> mkSynTypar typar |> Expr.Typar
+    | SynExpr.DotLambda(
+        expr = e
+        trivia = { DotRange = mDot
+                   UnderscoreRange = mUnderscore }) ->
+        ExprDotLambda(stn "_" mUnderscore, stn "." mDot, mkExpr creationAide e, exprRange)
+        |> Expr.DotLambda
     | _ -> failwithf "todo for %A" e
 
 let mkExprQuote creationAide isRaw e range : ExprQuoteNode =

src/Fantomas.Core/CodePrinter.fs

@@ -1557,6 +1557,11 @@ let genExpr (e: Expr) =
         |> genNode node
     | Expr.IndexFromEnd node -> !- "^" +> genExpr node.Expr |> genNode node
     | Expr.Typar node -> genSingleTextNode node
+    | Expr.DotLambda node ->
+        genSingleTextNode node.Underscore
+        +> genSingleTextNode node.Dot
+        +> genExpr node.Expr
+        |> genNode node
 
 let genQuoteExpr (node: ExprQuoteNode) =
     genSingleTextNode node.OpenToken
@@ -2435,6 +2440,7 @@ let genAppWithLambda sep (node: ExprAppWithLambdaNode) =
 
 let sepSpaceBeforeParenInFuncInvocation (functionExpr: Expr) (argExpr: Expr) ctx =
     match functionExpr, argExpr with
+    | Expr.DotLambda _, _ -> ctx
     | Expr.Constant _, _ -> sepSpace ctx
     | ParenExpr _, _ -> sepSpace ctx
     | UppercaseExpr, ParenExpr _ -> onlyIf ctx.Config.SpaceBeforeUppercaseInvocation sepSpace ctx

src/Fantomas.Core/SyntaxOak.fs

@@ -1604,6 +1604,13 @@ type ExprIndexFromEndNode(expr: Expr, range) =
     override val Children: Node array = [| Expr.Node expr |]
     member val Expr = expr
 
+type ExprDotLambda(underscore: SingleTextNode, dot: SingleTextNode, expr: Expr, range: range) =
+    inherit NodeBase(range)
+    override val Children: Node array = [| underscore; dot; Expr.Node expr |]
+    member val Underscore = underscore
+    member val Dot = dot
+    member val Expr = expr
+
 [<RequireQualifiedAccess; NoEquality; NoComparison>]
 type Expr =
     | Lazy of ExprLazyNode
@@ -1668,6 +1675,7 @@ type Expr =
     | IndexFromEnd of ExprIndexFromEndNode
     | Typar of SingleTextNode
     | Chain of ExprChain
+    | DotLambda of ExprDotLambda
 
     static member Node(x: Expr) : Node =
         match x with
@@ -1733,6 +1741,7 @@ type Expr =
         | IndexFromEnd n -> n
         | Typar n -> n
         | Chain n -> n
+        | DotLambda n -> n
 
     member e.HasParentheses: bool =
         match e with