FavourNestedFunctions: hook cfg & add docs

Updated Configuration.fs and fsharplint.json to include
FavourNestedFunctions rule. Added docs.

Author: webwarrior-ws

docs/content/how-tos/rule-configuration.md

@@ -127,3 +127,4 @@ The following rules can be specified for linting.
 - [FavourNonMutablePropertyInitialization (FL0084)](rules/FL0084.html)
 - [EnsureTailCallDiagnosticsInRecursiveFunctions (FL0085)](rules/FL0085.html)
 - [FavourAsKeyword (FL0086)](rules/FL0086.html)
+- [FavourNestedFunctions (FL0087)](rules/FL0087.html)

docs/content/how-tos/rules/FL0087.md

@@ -0,0 +1,31 @@
+---
+title: FL0087
+category: how-to
+hide_menu: true
+---
+
+# FavourNestedFunctions (FL0087)
+
+*Introduced in `0.24.3`*
+
+## Cause
+
+Prefer using local (nested) functions over private module-level functions.
+
+## Rationale
+
+With a nested function, one can clearly see from reading the code that there is only one consumer of the function.
+The code being this way becomes more streamlined.
+Code is also more concise because nested functions don't need accessibility modifiers.
+
+## How To Fix
+
+Move private function inside function that uses it.
+
+## Rule Settings
+
+    {
+        "FavourNestedFunctions": {
+            "enabled": false
+        }
+    }

src/FSharpLint.Core/Application/Configuration.fs

@@ -309,7 +309,8 @@ type ConventionsConfig =
       favourConsistentThis:RuleConfig<FavourConsistentThis.Config> option
       suggestUseAutoProperty:EnabledConfig option
       usedUnderscorePrefixedElements:EnabledConfig option
-      ensureTailCallDiagnosticsInRecursiveFunctions:EnabledConfig option}
+      ensureTailCallDiagnosticsInRecursiveFunctions:EnabledConfig option
+      favourNestedFunctions:EnabledConfig option }
 with
     member this.Flatten() =
         [|
@@ -335,6 +336,7 @@ with
             this.binding |> Option.map (fun config -> config.Flatten()) |> Option.toArray |> Array.concat
             this.suggestUseAutoProperty |> Option.bind (constructRuleIfEnabled SuggestUseAutoProperty.rule) |> Option.toArray
             this.ensureTailCallDiagnosticsInRecursiveFunctions |> Option.bind (constructRuleIfEnabled EnsureTailCallDiagnosticsInRecursiveFunctions.rule) |> Option.toArray
+            this.favourNestedFunctions |> Option.bind (constructRuleIfEnabled FavourNestedFunctions.rule) |> Option.toArray
         |] |> Array.concat
 
 type TypographyConfig =
@@ -459,9 +461,10 @@ type Configuration =
       TrailingNewLineInFile:EnabledConfig option
       NoTabCharacters:EnabledConfig option
       NoPartialFunctions:RuleConfig<NoPartialFunctions.Config> option
-      SuggestUseAutoProperty:EnabledConfig option
       EnsureTailCallDiagnosticsInRecursiveFunctions:EnabledConfig option
-      FavourAsKeyword:EnabledConfig option }
+      FavourAsKeyword:EnabledConfig option
+      SuggestUseAutoProperty:EnabledConfig option
+      FavourNestedFunctions:EnabledConfig option }
 with
     static member Zero = {
         Global = None
@@ -556,6 +559,7 @@ with
         SuggestUseAutoProperty = None
         EnsureTailCallDiagnosticsInRecursiveFunctions = None
         FavourAsKeyword = None
+        FavourNestedFunctions = None
     }
 
 // fsharplint:enable RecordFieldNames
@@ -714,6 +718,7 @@ let flattenConfig (config:Configuration) =
             config.SuggestUseAutoProperty |> Option.bind (constructRuleIfEnabled SuggestUseAutoProperty.rule)
             config.EnsureTailCallDiagnosticsInRecursiveFunctions |> Option.bind (constructRuleIfEnabled EnsureTailCallDiagnosticsInRecursiveFunctions.rule)
             config.FavourAsKeyword |> Option.bind (constructRuleIfEnabled FavourAsKeyword.rule)
+            config.FavourNestedFunctions |> Option.bind (constructRuleIfEnabled FavourNestedFunctions.rule)
         |] |> Array.choose id
 
     if config.NonPublicValuesNames.IsSome &&

src/FSharpLint.Core/fsharplint.json

@@ -333,6 +333,7 @@
     },
     "ensureTailCallDiagnosticsInRecursiveFunctions": { "enabled": false },
     "favourAsKeyword": { "enabled": true },
+    "favourNestedFunctions": { "enabled": false },
     "hints": {
         "add": [
             "not (a =  b) ===> a <> b",