Support `.len()` on reflective lists and maps

Signed-off-by: Olivier <olivier@librepush.net>

hornbeam_interpreter/src/functions/defaults.rs

@@ -1,5 +1,6 @@
 use std::{collections::BTreeMap, sync::Arc};
 
+use bevy_reflect::ReflectRef;
 use percent_encoding::NON_ALPHANUMERIC;
 
 use crate::interface::Value;
@@ -93,15 +94,25 @@ pub fn len(obj: Value, args: Vec<Value>) -> Result<Value, String> {
         return Err(format!("len takes 0 args, not {}", args.len()));
     }
 
-    match obj {
-        Value::Str(string) => Ok(Value::Int(string.len() as i64)),
-        Value::List(list) => Ok(Value::Int(list.len() as i64)),
+    Ok(Value::Int(match obj {
+        Value::Str(string) => string.len() as i64,
+        Value::List(list) => list.len() as i64,
+        Value::Reflective(reflect) => match reflect.reflect_ref() {
+            ReflectRef::List(list) => list.len() as i64,
+            ReflectRef::Array(array) => array.len() as i64,
+            ReflectRef::Map(map) => map.len() as i64,
+            _ => {
+                return Err(format!(
+                    "reflective {reflect:?} is not a list or map: can't get length!"
+                ));
+            }
+        },
         _ => {
             return Err(format!(
                 "{obj:?} is not a string or list: can't get length!"
             ));
         }
-    }
+    }))
 }
 
 /// Splits a string by given delimiters.