Fix issue for uncurried functions where the internal definition of Js.Fn.arity is shown on hover

Uncurried types are handled by the outcome printer. Add some additional logic on hover to recognize `Js.Fn.arityxx`, and avoid showing the type definition, which is internal.

Author: cristianoc

Changes.md

@@ -1,6 +1,7 @@
 ## master
 - Add support for autocomplete for `foo->`: the type of `foo` is used to determine the module to take completions from.
 - Add support for autocomplete for decorators such as `@module` and `@val`.
+- Fix issue for uncurried functions where the internal definition of `Js.Fn.arity` is shown on hover. (See https://github.com/rescript-lang/rescript-editor-support/issues/62).
 
 ## Release 1.0.5 of rescript-vscode
 This [commit](https://github.com/rescript-lang/rescript-editor-support/commit/6bdd10f6af259edc5f9cbe5b9df06836de3ab865) is vendored in [rescript-vscode 1.0.5](https://github.com/rescript-lang/rescript-vscode/releases/tag/1.0.5).

src/rescript-editor-support/Hover.re

@@ -120,7 +120,13 @@ let newHover = (~rootUri, ~file: SharedTypes.file, ~getModule, loc) => {
         let%opt path = typ |> Shared.digConstructor;
         let%opt (_env, {docstring, name: {txt}, item: {decl}}) =
           digConstructor(~env, ~getModule, path);
-        Some((decl |> Shared.declToString(txt), docstring));
+        let isUncurriedInternal =
+          Utils.startsWith(Path.name(path), "Js.Fn.arity");
+        if (isUncurriedInternal) {
+          None;
+        } else {
+          Some((decl |> Shared.declToString(txt), docstring));
+        };
       };
       let (typeString, docstring) =
         switch (extraTypeInfo) {