CSharpLanguageServer.Handlers.Implementation: rewrite in a more functional approach

Author: razzmatazz

src/CSharpLanguageServer/Handlers/Implementation.fs

@@ -11,22 +11,17 @@ module Implementation =
     let provider (_: ClientCapabilities) : U3<bool, ImplementationOptions, ImplementationRegistrationOptions> option =
         Some(U3.C1 true)
 
+    let findImplementationsOfSymbol (context: ServerRequestContext) sym = async {
+        let! impls = context.FindImplementations sym
+        let! locations = impls |> Seq.map (flip context.ResolveSymbolLocations None) |> Async.Parallel
+
+        return locations |> Array.collect List.toArray |> Declaration.C2 |> U2.C1 |> Some
+    }
+
     let handle
         (context: ServerRequestContext)
         (p: ImplementationParams)
         : Async<LspResult<U2<Definition, DefinitionLink array> option>> =
-        async {
-            match! context.FindSymbol p.TextDocument.Uri p.Position with
-            | None -> return None |> LspResult.success
-            | Some symbol ->
-                let! impls = context.FindImplementations symbol
-                let! locations = impls |> Seq.map (flip context.ResolveSymbolLocations None) |> Async.Parallel
-
-                return
-                    locations
-                    |> Array.collect List.toArray
-                    |> Declaration.C2
-                    |> U2.C1
-                    |> Some
-                    |> LspResult.success
-        }
+        context.FindSymbol p.TextDocument.Uri p.Position
+        |> Async.bindOption (findImplementationsOfSymbol context)
+        |> Async.map LspResult.success