fix: make typing-extension optional dependency

pyproject.toml

@@ -3,7 +3,7 @@ name = "mistune"
 description = "A sane and fast Markdown parser with useful plugins and renderers"
 authors = [{name = "Hsiaoming Yang", email="me@lepture.com"}]
 dependencies = [
-  "typing-extensions",
+  "typing-extensions; python_version<'3.11'",
 ]
 license = {text = "BSD-3-Clause"}
 dynamic = ["version"]
@@ -18,7 +18,6 @@ classifiers = [
   "Operating System :: OS Independent",
   "Programming Language :: Python",
   "Programming Language :: Python :: 3",
-  "Programming Language :: Python :: 3.7",
   "Programming Language :: Python :: 3.8",
   "Programming Language :: Python :: 3.9",
   "Programming Language :: Python :: 3.10",

src/mistune/__init__.py

@@ -8,10 +8,11 @@
     Documentation: https://mistune.lepture.com/
 """
 
-from typing import Any, Dict, Iterable, List, Optional, Tuple, Union
-
-from typing_extensions import Literal
-
+try:
+    import typing_extensions
+except ImportError:
+    pass
+from typing import Any, Dict, Iterable, List, Optional, Tuple, Union, Literal
 from .block_parser import BlockParser
 from .core import BaseRenderer, BlockState, InlineState
 from .inline_parser import InlineParser

src/mistune/core.py

@@ -14,9 +14,9 @@
     Type,
     TypeVar,
     Union,
+    Self,
     cast,
 )
-from typing_extensions import Self
 
 _LINE_END = re.compile(r'\n|$')
 

src/mistune/list_parser.py

@@ -2,8 +2,6 @@
 
 import re
 from typing import TYPE_CHECKING, Any, Dict, Iterable, List, Optional, Tuple, Match
-
-
 from .util import expand_leading_tab, expand_tab, strip_end
 
 if TYPE_CHECKING:

src/mistune/renderers/html.py

@@ -1,7 +1,4 @@
-from typing import Any, ClassVar, Dict, Optional, Tuple
-
-from typing_extensions import Literal
-
+from typing import Any, ClassVar, Dict, Optional, Tuple, Literal
 from ..core import BaseRenderer, BlockState
 from ..util import escape as escape_text
 from ..util import safe_entity, striptags