Revisit if/then/else according to MS style guide. (#1282)

* Revisit if/then/else according to MS style guide.

* Removed unused code

* Update documentation.

* Remove foldi function.

docs/Documentation.md

@@ -431,28 +431,26 @@ let b = [|4;5;6|]
 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).
 There is stated:
 
-> If either cond, e1 or e2 are longer, but not multi-line:
-> if cond
-> then e1
-> else e2
+> Indentation of conditionals depends on the size and complexity of the expressions that make them up. Write them on one line when:
+> cond, e1, and e2 are short
+> e1 and e2 are not if/then/else expressions themselves.
 
-This setting controls what exactly short means in terms of character count.
+This setting facilitates this by determining the maximum character width where the if/then/else expression stays in one line.
 Default = 40.
 
 `defaultConfig`
 
 ```fsharp
-if System.Char.IsUpper(c) then sprintf "_%s" (c.ToString().ToLower()) else c.ToString()
+if myCheck then truth else bogus
 ```
 
-Neither of the expression is longer than the default 40 here.
-
-`{ defaultConfig with MaxIfThenElseShortWidth = 30 }`
+`{ defaultConfig with MaxIfThenElseShortWidth = 10 }`
 
 ```fsharp
-if System.Char.IsUpper(c)
-then sprintf "_%s" (c.ToString().ToLower())
-else c.ToString()
+if myCheck then 
+    truth 
+else 
+    bogus
 ```
 
 ### fsharp_max_infix_operator_expression
@@ -821,6 +819,13 @@ type Range =
 
 ### fsharp_keep_if_then_in_same_line
 
+**Deprecated setting!**
+
+This setting will be removed in the next major version of Fantomas.
+As of 4.4, it has no effect anymore due to a change in the MS F# style guide.
+
+#### Original description:
+
 Bypasses the situation where `if`,`then` and `else` are placed underneath each other.
 This will ensure `if` and `then` are kept in the same line.
 Default = false.

src/Fantomas.Tests/ActivePatternTests.fs

@@ -46,7 +46,8 @@ let (|ParseRegex|_|) regex str =
    else None"""
         ({ config with
                MaxValueBindingWidth = 30
-               MaxFunctionBindingWidth = 30 })
+               MaxFunctionBindingWidth = 30
+               MaxIfThenElseShortWidth = 70 })
     |> prepend newline
     |> should equal """
 let (|Even|Odd|) input =
@@ -59,7 +60,8 @@ let (|Integer|_|) (str: string) =
 let (|ParseRegex|_|) regex str =
     let m = Regex(regex).Match(str)
 
-    if m.Success
-    then Some(List.tail [ for x in m.Groups -> x.Value ])
-    else None
+    if m.Success then
+        Some(List.tail [ for x in m.Groups -> x.Value ])
+    else
+        None
 """

src/Fantomas.Tests/AppTests.fs

@@ -380,7 +380,8 @@ type Queue<'T>(data: list<'T []>, length: int) =
 type Queue<'T>(data: list<'T []>, length: int) =
 
     member this.Head =
-        if length > 0
-        then (List.head data).[0]
-        else raise (System.Exception("Queue is empty"))
+        if length > 0 then
+            (List.head data).[0]
+        else
+            raise (System.Exception("Queue is empty"))
 """

src/Fantomas.Tests/CompilerDirectivesTests.fs

@@ -1850,7 +1850,9 @@ let getDefaultProxyFor =
             match calcEnvProxies.Force().TryFind uri.Scheme with
             | Some p -> if p.GetProxy uri <> uri then p else getDefault()
             | None -> getDefault())
-"""  config
+"""
+        { config with
+              MaxIfThenElseShortWidth = 50 }
     |> prepend newline
     |> should equal """
 let getDefaultProxyFor =

src/Fantomas.Tests/ComputationExpressionTests.fs

@@ -792,7 +792,9 @@ let ``let + let + let bang + if/then/else in ce`` () =
         else
             return ()
     }
-"""  config
+"""
+        { config with
+              MaxIfThenElseShortWidth = 75 }
     |> prepend newline
     |> should equal """
 let rec private appendToAzureTableStorage (cosmoEvents: EventWrite<JsonValue> seq) =
@@ -1643,7 +1645,9 @@ let create: Highlighter =
                 }
                 |> List.ofSeq
                 |> FormattedText.fromList
-"""  config
+"""
+        { config with
+              MaxIfThenElseShortWidth = 80 }
     |> prepend newline
     |> should equal """
 let create: Highlighter =
@@ -1664,10 +1668,10 @@ let create: Highlighter =
                         yield TextSpan.highlight ms.[i].Value
                         let regStart = ms.[i].Index + ms.[i].Length
 
-                        if i < ms.Count - 1
-                        then yield TextSpan.normal (s.Substring(regStart, ms.[i + 1].Index - regStart))
-                        elif regStart < s.Length
-                        then yield TextSpan.normal (s.Substring(regStart))
+                        if i < ms.Count - 1 then
+                            yield TextSpan.normal (s.Substring(regStart, ms.[i + 1].Index - regStart))
+                        elif regStart < s.Length then
+                            yield TextSpan.normal (s.Substring(regStart))
 
                 }
                 |> List.ofSeq

src/Fantomas.Tests/ControlStructureTests.fs

@@ -21,7 +21,9 @@ let test x y =
   else "Don't know"
 
 if age < 10
-then printfn "You are only %d years old and already learning F#? Wow!" age""" config
+then printfn "You are only %d years old and already learning F#? Wow!" age"""
+        { config with
+              MaxIfThenElseShortWidth = 60 }
     |> prepend newline
     |> should equal """
 let rec tryFindMatch pred list =
@@ -141,7 +143,10 @@ let ``try/with and finally`` () =
 let function1 x y =
     try
         try
-            if x = y then raise (InnerError("inner")) else raise (OuterError("outer"))
+            if x = y then
+                raise (InnerError("inner"))
+            else
+                raise (OuterError("outer"))
         with
         | Failure _ -> ()
         | InnerError (str) -> printfn "Error1 %s" str
@@ -542,7 +547,9 @@ let internal coli f' (c: seq<'T>) f (ctx: Context) =
         i <- i + 1
 
     st
-"""  config
+"""
+        { config with
+              MaxIfThenElseShortWidth = 50 }
     |> prepend newline
     |> should equal """
 let internal coli f' (c: seq<'T>) f (ctx: Context) =

src/Fantomas.Tests/DynamicOperatorTests.fs

@@ -28,9 +28,10 @@ let ``keep () when dynamic operator inside boolean expr, #476`` () =
     |> prepend newline
     |> should equal """
 let fieldColor (fieldNameX: string) =
-    if f.errors?(fieldNameY) && f.touched?(fieldNameZ)
-    then IsDanger
-    else NoColor
+    if f.errors?(fieldNameY) && f.touched?(fieldNameZ) then
+        IsDanger
+    else
+        NoColor
     |> Input.Color
 """