fix issues

Author: timfennis

ndc_lib/src/interpreter/environment.rs

@@ -203,7 +203,7 @@ impl Environment {
                     depth: depth - 1,
                     slot,
                 }),
-            ResolvedVar::Global { slot } => todo!("probably disallow taking global variables"),
+            ResolvedVar::Global { .. } => panic!("cannot take global variable from environment"),
         }
     }
 

ndc_lib/src/stdlib/hash_map.rs

@@ -77,13 +77,12 @@ mod inner {
         }
     }
 
-    // TODO: adding this function breaks the new function resolution
-    // #[function(name = "-=")]
-    // pub fn difference_assign(lhs: &mut MapRepr, rhs: &mut MapRepr) {
-    //     let left_map: &mut HashMap<Value, Value> = &mut lhs.borrow_mut();
-    //
-    //     left_map.difference(&*rhs.borrow());
-    // }
+    #[function(name = "-=")]
+    pub fn difference_assign(lhs: &mut MapRepr, rhs: &mut MapRepr) {
+        let left_map: &mut HashMap<Value, Value> = &mut lhs.borrow_mut();
+
+        left_map.difference(&*rhs.borrow());
+    }
 
     #[function(name = "~=")]
     pub fn symmetric_difference_assign(lhs: &mut MapRepr, rhs: &mut MapRepr) {