Revisit if/then/else

CHANGELOG.md

@@ -6,6 +6,10 @@
 * Restore the CodeFormatter.MakeRange public API. [#2306](https://github.com/fsprojects/fantomas/pull/2306)
 * Update FCS to 'Add arrow to SynType.Fun trivia.', commit 5a5a5f6cd07aa4a8326baa07d4f7af1305ced6f4
 * Update FCS to 'Fix setter first', commit 267d0a57f217df756d9ac33c6aa4ffbfe3b53097
+* Update style of long if/match expressions (See [fslang-design#646](https://github.com/fsharp/fslang-design/issues/646)). [#2334](https://github.com/fsprojects/fantomas/pull/2334)
+
+### Added
+* Add setting `fsharp_max_if_then_short_width`. [#2299](https://github.com/fsprojects/fantomas/issues/2299)
 
 ## [5.0.0-alpha-010] - 2022-06-27
 

docs-old/Documentation.md

@@ -122,6 +122,7 @@ 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=40
 fsharp_max_infix_operator_expression=50
 fsharp_max_record_width=40
@@ -442,6 +443,26 @@ let a = [1;2;3]
 let b = [|4;5;6|]
 ```
 
+### fsharp_max_if_then_short_width
+
+Control the maximum length for which if/then expression without an else expression can be on one line.  
+The [Microsoft F# style guide](https://docs.microsoft.com/en-us/dotnet/fsharp/style-guide/formatting#formatting-if-expressions) recommends to never write such an expression in one line.
+> If the else expression is absent, it is recommended to never to write the entire expression in one line.
+Default = 0.
+
+`defaultConfig`
+
+```fsharp
+if a then 
+    ()
+```
+
+`{ defaultConfig with MaxIfThenShortWidth = 15 }`
+
+```fsharp
+if a then ()
+```
+
 ### fsharp_max_if_then_else_short_width
 
 Fantomas by default follows the if/then/else conventions listed in the [Microsoft F# style guide](https://docs.microsoft.com/en-us/dotnet/fsharp/style-guide/formatting#formatting-if-expressions).

src/Fantomas.Core.Tests/ActivePatternTests.fs

@@ -64,7 +64,7 @@ let (|ParseRegex|_|) regex str =
         { config with
             MaxValueBindingWidth = 30
             MaxFunctionBindingWidth = 30
-            MaxIfThenElseShortWidth = 70 }
+            MaxIfThenElseShortWidth = 75 }
     |> prepend newline
     |> should
         equal

src/Fantomas.Core.Tests/AppTests.fs

@@ -486,35 +486,33 @@ let ``parenthesis around composed function expression, 1341`` () =
 
 [<Test>]
 let ``parenthesis around short composed function expression, tuple, 1700`` () =
-    formatSourceString false """((=) (ownerName, username))""" config
-    |> should
-        equal
-        """((=) (ownerName, username))
-"""
+    formatSourceString false "((=) (ownerName, username))" { config with InsertFinalNewline = false }
+    |> should equal "((=) (ownerName, username))"
 
 [<Test>]
 let ``parenthesis around short composed function expression, tuple in if, 1700`` () =
-    formatSourceString false """if ((=) (ownerName, username)) then 6""" config
-    |> should
-        equal
-        """if ((=) (ownerName, username)) then 6
-"""
+    formatSourceString
+        false
+        "if ((=) (ownerName, username)) then 6"
+        { config with
+            MaxIfThenShortWidth = 40
+            InsertFinalNewline = false }
+    |> should equal "if ((=) (ownerName, username)) then 6"
 
 [<Test>]
 let ``parenthesis around short composed function expression, no tuple, 1700`` () =
-    formatSourceString false """((=) ownerName)""" config
-    |> should
-        equal
-        """((=) ownerName)
-"""
+    formatSourceString false """((=) ownerName)""" { config with InsertFinalNewline = false }
+    |> should equal """((=) ownerName)"""
 
 [<Test>]
 let ``parenthesis around short composed function expression, no tuple in if, 1700, part 2`` () =
-    formatSourceString false """if ((=) ownerName) then 6""" config
-    |> should
-        equal
-        """if ((=) ownerName) then 6
-"""
+    formatSourceString
+        false
+        "if ((=) ownerName) then 6"
+        { config with
+            MaxIfThenShortWidth = 25
+            InsertFinalNewline = false }
+    |> should equal "if ((=) ownerName) then 6"
 
 [<Test>]
 let ``parenthesis around simple function expression`` () =

src/Fantomas.Core.Tests/CommentTests.fs

@@ -495,7 +495,9 @@ if a then
     ()
 else
 // Comment 1
-if b then
+if
+    b
+then
     ()
 // Comment 2
 else
@@ -993,7 +995,8 @@ else 0"""
         equal
         """
 if //comment
-    true then
+    true
+then
     1
 else
     0

src/Fantomas.Core.Tests/CompilerDirectivesTests.fs

@@ -1646,7 +1646,7 @@ module Dbg =
     let print _ = ()
 #endif
 """
-        config
+        { config with MaxIfThenShortWidth = 30 }
     |> prepend newline
     |> should
         equal
@@ -1704,7 +1704,7 @@ module Dbg =
     let print _ = ()
 #endif
 """
-        config
+        { config with MaxIfThenShortWidth = 30 }
     |> prepend newline
     |> should
         equal
@@ -2504,7 +2504,7 @@ let ``comment after compiler define`` () =
     let tcrefObjTy, enclosingDeclaredTypars, renaming, objTy = FreshenTyconRef m rigid tcref declaredTyconTypars
 #endif
 """
-        config
+        { config with MaxIfThenElseShortWidth = 20 }
     |> prepend newline
     |> should
         equal

src/Fantomas.Core.Tests/ComputationExpressionTests.fs

@@ -1909,7 +1909,9 @@ let create: Highlighter =
                 |> List.ofSeq
                 |> FormattedText.fromList
 """
-        { config with MaxIfThenElseShortWidth = 80 }
+        { config with
+            MaxIfThenElseShortWidth = 80
+            MaxIfThenShortWidth = 80 }
     |> prepend newline
     |> should
         equal

src/Fantomas.Core.Tests/ControlStructureTests.fs

@@ -389,7 +389,7 @@ let ``if/elif without else`` () =
 if true then ()
 elif true then ()
     """
-        config
+        { config with MaxIfThenShortWidth = 20 }
     |> prepend newline
     |> should
         equal

src/Fantomas.Core.Tests/DotGetTests.fs

@@ -947,15 +947,19 @@ let PublishValueDefn cenv env declKind (vspec: Val) =
         equal
         """
 let PublishValueDefn cenv env declKind (vspec: Val) =
-    if (declKind = ModuleOrMemberBinding)
-       && ((GetCurrAccumulatedModuleOrNamespaceType env)
-              .ModuleOrNamespaceKind = Namespace)
-       && (Option.isNone vspec.MemberInfo) then
+    if
+        (declKind = ModuleOrMemberBinding)
+        && ((GetCurrAccumulatedModuleOrNamespaceType env)
+               .ModuleOrNamespaceKind = Namespace)
+        && (Option.isNone vspec.MemberInfo)
+    then
         errorR (Error(FSComp.SR.tcNamespaceCannotContainValues (), vspec.Range))
 
-    if (declKind = ExtrinsicExtensionBinding)
-       && ((GetCurrAccumulatedModuleOrNamespaceType env)
-              .ModuleOrNamespaceKind = Namespace) then
+    if
+        (declKind = ExtrinsicExtensionBinding)
+        && ((GetCurrAccumulatedModuleOrNamespaceType env)
+               .ModuleOrNamespaceKind = Namespace)
+    then
         errorR (Error(FSComp.SR.tcNamespaceCannotContainExtensionMembers (), vspec.Range))
 
     ()

src/Fantomas.Core.Tests/DynamicOperatorTests.fs

@@ -31,7 +31,7 @@ let ``keep () when dynamic operator inside boolean expr, #476`` () =
         NoColor
     |> Input.Color
 """
-        config
+        { config with MaxIfThenElseShortWidth = 5 }
     |> prepend newline
     |> should
         equal

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

@@ -111,6 +111,7 @@
     <Compile Include="IdentTests.fs" />
     <Compile Include="RecordDeclarationsWithXMLDocTests.fs" />
     <Compile Include="AstExtensionsTests.fs" />
+    <Compile Include="MaxIfThenShortWidthTests.fs" />
   </ItemGroup>
   <ItemGroup>
     <ProjectReference Include="..\Fantomas.Extras\Fantomas.Extras.fsproj" />