Add Dynamic::is_XXX API.

src/api/build_type.rs

@@ -99,6 +99,10 @@ impl Engine {
 ///
 /// To define a pretty-print name, call [`with_name`][`TypeBuilder::with_name`],
 /// to use [`Engine::register_type_with_name`] instead.
+///
+/// # WARNING - Volatile Type
+///
+/// This type is volatile and may change in the future.
 #[deprecated = "This type is NOT deprecated, but it is considered volatile and may change in the future."]
 pub struct TypeBuilder<'a, T: Variant + Clone> {
     engine: &'a mut Engine,

src/api/custom_syntax.rs

@@ -89,6 +89,7 @@ impl Expression<'_> {
     /// # WARNING - Low Level API
     ///
     /// This function is _extremely_ low level.  It evaluates an expression from an [`AST`][crate::AST].
+    #[deprecated = "This API is NOT deprecated, but it is considered volatile and may change in the future."]
     #[inline(always)]
     pub fn eval_with_context_raw(
         &self,

src/api/json.rs

@@ -166,7 +166,7 @@ pub fn format_map_as_json(map: &Map) -> String {
 
         if let Some(val) = value.read_lock::<Map>() {
             result.push_str(&format_map_as_json(&*val));
-        } else if value.is::<()>() {
+        } else if value.is_unit() {
             result.push_str("null");
         } else {
             write!(result, "{:?}", value).unwrap();