feat: handle not operator

midas/checker/midas.py

@@ -28,7 +28,7 @@ from midas.checker.types import (
 )
 from midas.checker.variance import VarianceInferrer
 from midas.lexer.midas import MidasLexer
-from midas.lexer.token import Token
+from midas.lexer.token import Token, TokenType
 from midas.parser.midas import MidasParser
 
 
@@ -297,6 +297,11 @@ class MidasTyper(m.Stmt.Visitor[None], m.Expr.Visitor[Type], m.Type.Visitor[Type
         return result.result
 
     def visit_unary_expr(self, expr: m.UnaryExpr) -> Type:
+        # Special case because there is no __not__ dunder method
+        match expr.operator:
+            case Token(type=TokenType.BANG):
+                return self.types.get_type("bool")
+
         method: Optional[str] = MIDAS_UNARY_METHODS.get(expr.operator.type)
         if method is None:
             self.logger.warning(f"Unsupported operator {expr.operator.lexeme}")

midas/checker/python.py

@@ -686,6 +686,11 @@ class PythonTyper(
             return UnknownType()
 
     def visit_unary_expr(self, expr: p.UnaryExpr) -> Type:
+        # Special case because there is no __not__ dunder method
+        match expr.operator:
+            case ast.Not():
+                return self.types.get_type("bool")
+
         method: Optional[str] = PY_UNARY_METHODS.get(expr.operator.__class__)
         if method is None:
             self.logger.warning(f"Unsupported operator {expr.operator}")

midas/lexer/midas.py

@@ -32,6 +32,8 @@ class MidasLexer(Lexer):
                 )
             case "!" if self.match("="):
                 self.add_token(TokenType.BANG_EQUAL)
+            case "!":
+                self.add_token(TokenType.BANG)
             case ":":
                 self.add_token(TokenType.COLON)
             case ".":

midas/lexer/token.py

@@ -36,6 +36,7 @@ class TokenType(Enum):
     EQUAL = auto()
     EQUAL_EQUAL = auto()
     BANG_EQUAL = auto()
+    BANG = auto()
 
     # Literals
     IDENTIFIER = auto()

midas/parser/midas.py

@@ -487,12 +487,12 @@ class MidasParser(Parser[list[Stmt]]):
         """Parse a unary expression
 
         A unary consists of a call expression (see :func:`call`) optionally
-        preceded by zero or more unary operators (`+`, `-`)
+        preceded by zero or more unary operators (`+`, `-`, `!`)
 
         Returns:
             Expr: the parsed expression
         """
-        if self.match(TokenType.PLUS, TokenType.MINUS):
+        if self.match(TokenType.PLUS, TokenType.MINUS, TokenType.BANG):
             operator: Token = self.previous()
             right: Expr = self.unary()
             location: Location = Location.span(operator.get_location(), right.location)