diff --git a/gen/midas.py b/gen/midas.py
index 4141217..72813d4 100644
--- a/gen/midas.py
+++ b/gen/midas.py
@@ -4,6 +4,7 @@
 ###> Imports
 from abc import ABC, abstractmethod
 from dataclasses import dataclass
+from enum import Enum, auto
 from typing import Any, Generic, Optional, TypeVar
 
 from midas.ast.location import Location
@@ -20,6 +21,11 @@ class TypeParam:
     bound: Optional[Type]
 
 
+class MemberKind(Enum):
+    PROPERTY = auto()
+    METHOD = auto()
+
+
 ###<
 
 
@@ -33,12 +39,13 @@ class TypeStmt:
 class MemberStmt:
     name: Token
     type: Type
+    kind: MemberKind
 
 
 class ExtendStmt:
+    name: Token
     params: list[TypeParam]
-    type: Type
-    operations: list[OpStmt]
+    members: list[MemberStmt]
 
 
 class OpStmt:
diff --git a/midas/ast/midas.py b/midas/ast/midas.py
index 36d959b..affd768 100644
--- a/midas/ast/midas.py
+++ b/midas/ast/midas.py
@@ -7,6 +7,7 @@ from __future__ import annotations
 
 from abc import ABC, abstractmethod
 from dataclasses import dataclass
+from enum import Enum, auto
 from typing import Any, Generic, Optional, TypeVar
 
 from midas.ast.location import Location
@@ -21,6 +22,11 @@ class TypeParam:
     bound: Optional[Type]
 
 
+class MemberKind(Enum):
+    PROPERTY = auto()
+    METHOD = auto()
+
+
 ##############
 # Statements #
 ##############
@@ -64,6 +70,7 @@ class TypeStmt(Stmt):
 class MemberStmt(Stmt):
     name: Token
     type: Type
+    kind: MemberKind
 
     def accept(self, visitor: Stmt.Visitor[T]) -> T:
         return visitor.visit_member_stmt(self)
@@ -71,9 +78,9 @@ class MemberStmt(Stmt):
 
 @dataclass(frozen=True)
 class ExtendStmt(Stmt):
+    name: Token
     params: list[TypeParam]
-    type: Type
-    operations: list[OpStmt]
+    members: list[MemberStmt]
 
     def accept(self, visitor: Stmt.Visitor[T]) -> T:
         return visitor.visit_extend_stmt(self)
diff --git a/midas/ast/printer.py b/midas/ast/printer.py
index 2a5eec3..c9a9d33 100644
--- a/midas/ast/printer.py
+++ b/midas/ast/printer.py
@@ -114,6 +114,7 @@ class MidasAstPrinter(
     def visit_member_stmt(self, stmt: m.MemberStmt):
         self._write_line("MemberStmt")
         with self._child_level():
+            self._write_line(f"kind: {stmt.kind.name}")
             self._write_line(f'name: "{stmt.name.lexeme}"')
             self._write_line("type", last=True)
             with self._child_level(single=True):
@@ -129,16 +130,21 @@ class MidasAstPrinter(
                     if i == len(stmt.params) - 1:
                         self._mark_last()
                     self._print_type_param(param)
-            self._write_line("type")
-            with self._child_level(single=True):
-                stmt.type.accept(self)
-            self._write_line("operations", last=True)
+            self._write_line(f'name: "{stmt.name.lexeme}"')
+            self._write_line("params")
             with self._child_level():
-                for i, op in enumerate(stmt.operations):
+                for i, param in enumerate(stmt.params):
                     self._idx = i
-                    if i == len(stmt.operations) - 1:
+                    if i == len(stmt.params) - 1:
                         self._mark_last()
-                    op.accept(self)
+                    self._print_type_param(param)
+            self._write_line("members", last=True)
+            with self._child_level():
+                for i, member in enumerate(stmt.members):
+                    self._idx = i
+                    if i == len(stmt.members) - 1:
+                        self._mark_last()
+                    member.accept(self)
 
     def visit_op_stmt(self, stmt: m.OpStmt) -> None:
         self._write_line("OpStmt")
@@ -343,15 +349,23 @@ class MidasPrinter(m.Expr.Visitor[str], m.Stmt.Visitor[str], m.Type.Visitor[str]
         return res
 
     def visit_member_stmt(self, stmt: m.MemberStmt):
-        res: str = f"{stmt.name.lexeme}: {stmt.type.accept(self)}"
+        keyword: str = {
+            m.MemberKind.PROPERTY: "prop",
+            m.MemberKind.METHOD: "def",
+        }.get(stmt.kind, "")
+        res: str = f"{keyword} {stmt.name.lexeme}: {stmt.type.accept(self)}"
         return self.indented(res)
 
     def visit_extend_stmt(self, stmt: m.ExtendStmt):
-        res: str = self.indented(f"extend {stmt.type.accept(self)}")
+        template: str = ""
+        if len(stmt.params) != 0:
+            params: list[str] = [self._print_type_param(param) for param in stmt.params]
+            template = f"[{', '.join(params)}]"
+        res: str = self.indented(f"extend {stmt.name.lexeme}{template}")
         res += " {\n"
         self.level += 1
-        for op in stmt.operations:
-            res += op.accept(self)
+        for member in stmt.members:
+            res += member.accept(self) + "\n"
         self.level -= 1
         res += self.indented("}")
         return res
diff --git a/midas/lexer/token.py b/midas/lexer/token.py
index 60b6e47..95e0c18 100644
--- a/midas/lexer/token.py
+++ b/midas/lexer/token.py
@@ -50,6 +50,8 @@ class TokenType(Enum):
     PREDICATE = auto()
     EXTEND = auto()
     WHERE = auto()
+    PROP = auto()
+    DEF = auto()
     FUNC = auto()
 
     # Misc
@@ -68,6 +70,8 @@ KEYWORDS: dict[str, TokenType] = {
     "true": TokenType.TRUE,
     "false": TokenType.FALSE,
     "none": TokenType.NONE,
+    "prop": TokenType.PROP,
+    "def": TokenType.DEF,
     "fn": TokenType.FUNC,
 }
 
diff --git a/midas/parser/midas.py b/midas/parser/midas.py
index 0d0cbde..ce94b2d 100644
--- a/midas/parser/midas.py
+++ b/midas/parser/midas.py
@@ -14,6 +14,7 @@ from midas.ast.midas import (
     GroupingExpr,
     LiteralExpr,
     LogicalExpr,
+    MemberKind,
     MemberStmt,
     NamedType,
     OpStmt,
@@ -394,18 +395,28 @@ class MidasParser(Parser):
     def member_stmt(self) -> MemberStmt:
         """Parse a member statement
 
-        A type member statement is written `name: Type`
+        A type member statement is written `prop name: Type` or `def name: Type`
 
         Returns:
             MemberStmt: the parsed member statement
         """
+        kind: MemberKind
+        if self.match(TokenType.PROP):
+            kind = MemberKind.PROPERTY
+        elif self.match(TokenType.DEF):
+            kind = MemberKind.METHOD
+        else:
+            raise self.error(self.peek(), "Expected 'prop' or 'def'")
+
         name: Token = self.consume_identifier("Expected member name")
         self.consume(TokenType.COLON, "Expected ':' after member name")
+
         type: Type = self.type_expr()
         return MemberStmt(
             location=name.location_to(self.previous()),
             name=name,
             type=type,
+            kind=kind,
         )
 
     def extend_declaration(self) -> ExtendStmt:
@@ -417,20 +428,20 @@ class MidasParser(Parser):
             ExtendStmt: the parsed extension statement
         """
         keyword: Token = self.previous()
+        name: Token = self.consume_identifier("Expected type name")
         params: list[TypeParam] = self.type_params()
 
-        type: Type = self.type_expr()
         self.consume(TokenType.LEFT_BRACE, "Expected '{' to start extend body")
-        operations: list[OpStmt] = []
+        members: list[MemberStmt] = []
         while not self.is_at_end() and not self.check(TokenType.RIGHT_BRACE):
-            operations.append(self.op_declaration())
+            members.append(self.member_stmt())
         self.consume(TokenType.RIGHT_BRACE, "Unclosed extend body")
         location: Location = keyword.location_to(self.previous())
         return ExtendStmt(
             location=location,
+            name=name,
             params=params,
-            type=type,
-            operations=operations,
+            members=members,
         )
 
     def op_declaration(self) -> OpStmt: