Use isNull for null checks

src/Avalonia.FuncUI.Diagnostics/InspectorState.fs

@@ -84,7 +84,7 @@ module internal InspectorState =
 
         let removed = Set.difference last next
         for item in removed do
-            if item.Ref <> null then
+            if not (isNull (item.Ref)) then
                 ComponentHighlightAdorner.Remove item.Ref
 
         shared.Components.Set next

src/Avalonia.FuncUI.Diagnostics/Lib/Lib.ComponentAdorner.fs

@@ -21,7 +21,7 @@ type internal ComponentHighlightAdorner (adornedElement: Component) =
 
         let layer = AdornerLayer.GetAdornerLayer adornedElement
 
-        if layer <> null then
+        if not (isNull layer) then
             let alreadyAttached =
                 layer.Children
                 |> Seq.toList // copy to be safe
@@ -39,7 +39,7 @@ type internal ComponentHighlightAdorner (adornedElement: Component) =
     static member Remove (adornedElement: Component) =
         let layer = AdornerLayer.GetAdornerLayer adornedElement
 
-        if layer <> null then
+        if not (isNull layer) then
             layer.Children
             |> Seq.toList // copy to be safe
             |> Seq.filter (fun c -> c.GetType() = typeof<ComponentHighlightAdorner>)

src/Avalonia.FuncUI/Components/Lib/Lib.Common.fs

@@ -10,13 +10,13 @@ module internal ComponentHelpers =
         let ao: obj = a :> _
         let bo: obj = b :> _
 
-        if ao <> null then
-            if bo <> null then
+        if not (isNull ao) then
+            if not (isNull bo) then
                 ao.Equals(bo)
             else
                 false
         else
-            bo = null
+            isNull bo
 
 [<RequireQualifiedAccess>]
 module internal String =

src/Avalonia.FuncUI/Components/Lib/Lib.DisposableBag.fs

@@ -5,13 +5,13 @@ open System
 type internal DisposableBag () =
     let items = ResizeArray<IDisposable>()
     member this.Add (item: IDisposable) =
-        if item <> null then
+        if not (isNull item) then
             items.Add item
 
     interface IDisposable with
         member this.Dispose () =
             for item in items do
-                if item <> null then
+                if not (isNull item) then
                     item.Dispose ()
 
 

src/Avalonia.FuncUI/VirtualDom/VirtualDom.Patcher.fs

@@ -14,7 +14,7 @@ module internal rec Patcher =
     open System.Threading
 
     let private shouldPatch (value: obj, viewElement: ViewDelta) =
-         value <> null
+         not (isNull value)
          && value.GetType() = viewElement.ViewType
          && not viewElement.KeyDidChange
 
@@ -226,7 +226,7 @@ module internal rec Patcher =
 
     let create (viewElement: ViewDelta) : AvaloniaObject =
         let control =
-            if viewElement.ConstructorArgs <> null && viewElement.ConstructorArgs.Length > 0 then
+            if not (isNull (viewElement.ConstructorArgs)) && viewElement.ConstructorArgs.Length > 0 then
                 (viewElement.ViewType, viewElement.ConstructorArgs)
                 |> Activator.CreateInstance
                 |> Utils.cast<AvaloniaObject>

src/Avalonia.FuncUI/VirtualDom/VirtualDom.fs

@@ -18,7 +18,7 @@ module rec VirtualDom =
 
     let updateRoot (host: ContentControl, last: IView option, next: IView option) =
         let root : Control voption =
-            if host.Content <> null then
+            if not (isNull (host.Content)) then
                 match host.Content with
                 | :? Control as control -> ValueSome control
                 | _ -> ValueNone
@@ -54,7 +54,7 @@ module rec VirtualDom =
     // TODO: share code with updateRoot
     let internal updateBorderRoot (host: Border, last: IView option, next: IView option) =
         let root : Control voption =
-            if host.Child <> null then
+            if not (isNull (host.Child)) then
                 ValueSome host.Child
             else
                 ValueNone

src/Examples/Component Examples/Examples.DrawingApp/Program.fs

@@ -89,7 +89,7 @@ type Views =
                                 StrokeLineCap = PenLineCap.Round
                             )
 
-                            if canvasOutlet.Current <> null then
+                            if not (isNull (canvasOutlet.Current)) then
                                 canvasOutlet.Current.Children.Add line
 
                         | None ->

src/Examples/Component Examples/Examples.EnvApp/Program.fs

@@ -62,7 +62,7 @@ type Views =
                                 StrokeLineCap = PenLineCap.Round
                             )
 
-                            if canvasOutlet.Current <> null then
+                            if not (isNull (canvasOutlet.Current)) then
                                 canvasOutlet.Current.Children.Add line
 
                         | None ->