added normal assignment

boring/parse.py

@@ -109,7 +109,14 @@ class LetStatement:
     expression: Expression
 
 
-Statement = Union[LetStatement, Expression]
+@dataclass
+class AssignmentStatement:
+    variable_name: str
+    type: TypeUsage
+    expression: Expression
+
+
+Statement = Union[LetStatement, AssignmentStatement, Expression]
 
 
 @dataclass
@@ -177,7 +184,10 @@ boring_grammar = r"""
     let_statement : "let" identifier "=" expression ";"
                   | "let" identifier ":" type_usage "=" expression ";"
 
+    assignment_statement : identifier "=" expression ";"
+
     statement : let_statement
+              | assignment_statement
               | return_statement
               | expression
 
@@ -298,6 +308,14 @@ class TreeToBoring(Transformer):
             expression=expression,
         )
 
+    def assignment_statement(self, assignment_statement) -> AssignmentStatement:
+        (variable_name, expression) = assignment_statement
+        return AssignmentStatement(
+            variable_name=variable_name,
+            type=UnknownTypeUsage(),
+            expression=expression,
+        )
+
     def statement(self, statement):
         (statement,) = statement
         return statement