Format function calls with multiple lambdas as multiline. Fixes fspro…

…jects#1164.

src/Fantomas.Tests/LambdaTests.fs

@@ -472,3 +472,44 @@ Target.create "Install" (fun x ->
     // Paket restore will already happen when the build.fsx dependencies are restored
     )
 """
+
+[<Test>]
+let ``function call with two lambda arguments, 1164`` () =
+    formatSourceString false """
+let init =
+  addDateTimeConverter
+    (fun dt -> Date(dt.Year, dt.Month, dt.Day))
+    (fun (Date (y, m, d)) ->
+      System.DateTime(y, m, d))
+"""  { config with MaxLineLength = 85 }
+    |> prepend newline
+    |> should equal """
+let init =
+    addDateTimeConverter
+        (fun dt -> Date(dt.Year, dt.Month, dt.Day))
+        (fun (Date (y, m, d)) -> System.DateTime(y, m, d))
+"""
+
+[<Test>]
+let ``function call with two lambdas and three other arguments`` () =
+    formatSourceString false """
+SettingControls.toggleButton (fun _ ->
+    UpdateOption(key, MultilineFormatterTypeOption(o, key, "character_width"))
+    |> dispatch) (fun _ ->
+    UpdateOption(key, MultilineFormatterTypeOption(o, key, "number_of_items"))
+    |> dispatch) "CharacterWidth" "NumberOfItems" key (v = "character_width")
+"""  config
+    |> prepend newline
+    |> should equal """
+SettingControls.toggleButton
+    (fun _ ->
+        UpdateOption(key, MultilineFormatterTypeOption(o, key, "character_width"))
+        |> dispatch)
+    (fun _ ->
+        UpdateOption(key, MultilineFormatterTypeOption(o, key, "number_of_items"))
+        |> dispatch)
+    "CharacterWidth"
+    "NumberOfItems"
+    key
+    (v = "character_width")
+"""

src/Fantomas/CodePrinter.fs

@@ -1966,12 +1966,13 @@ and genExpr astContext synExpr =
                              +> genExpr astContext e
                              +> unindent))))
 
-        let hasThreeOrMoreLambdas =
+        let hasMultipleLambdas =
             List.filter (function
-                | Paren (_, Lambda _, _) -> true
+                | Paren (_, Lambda _, _)
+                | Paren (_, DesugaredLambda _, _) -> true
                 | _ -> false) es
             |> List.length
-            |> fun l -> l >= 3
+            |> fun l -> l > 1
 
         if List.exists (function
             | Lambda _
@@ -1981,7 +1982,7 @@ and genExpr astContext synExpr =
             | MultilineString _
             | CompExpr _ -> true
             | _ -> false) es
-           && not hasThreeOrMoreLambdas then
+           && not hasMultipleLambdas then
             shortExpression
         else
             expressionFitsOnRestOfLine shortExpression longExpression