operator overload

toy-impl/README.md

@@ -21,6 +21,11 @@ for simplicity reasons:
 * method override check modulo variable renaming.
 * more complicated type guard
 
+## Running Example
+```bash
+python main.py example/a.py
+```
+
 ## Files
 All files named `test_xxx` are used for inspecting the result of algorithms, and
 can be ignored for now.
@@ -198,5 +203,31 @@ This would fail. From the first argument, we have `A -> A`, and from the second
 argument we need `A -> B`. In general, we may have `A != B`, so there is no
 substitution that meets the requirement and the type check failed.
 
-## Operator Override
+## Operator Overloading
+Most operations are actually implemented via operator overloading.
+We currently support:
+* Normal:
+    * `__init__`
+* Comparison:
+    * `__lt__`
+    * `__le__`
+    * `__gt__`
+    * `__ge__`
+    * `__eq__`
+    * `__ne__`
+* Arithmetic:
+    * `__add__`
+    * `__sub__`
+    * `__mul__`
+    * `__matmul__`
+    * `__truediv__`
+    * `__floordiv__`
+    * `__mod__`
+    * `__pow__`
+    * `__lshift__`
+    * `__rshift__`
+    * `__and__`
+    * `__or__`
+    * `__xor__`
+    * `__neg__`