diff --git a/pyproject.toml b/pyproject.toml
index d606cd6ff..14261f29d 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -79,6 +79,7 @@ exclude = "(?x)(^tests/.*/fixtures | ^src/poetry/core/_vendor)"
 [[tool.mypy.overrides]]
 module = [
   'jsonschema.*',
+  'lark.*',
   'setuptools.*',
   'tomlkit.*',
 ]
@@ -99,8 +100,6 @@ module = [
   'poetry.core.packages.utils.utils',
   'poetry.core.packages.dependency',
   'poetry.core.packages.package',
-  'poetry.core.packages.project_package',
-  'poetry.core.semver.version_range',
   'poetry.core.semver.version_union',
   'poetry.core.toml.exceptions',
   'poetry.core.toml.file',
diff --git a/src/poetry/core/factory.py b/src/poetry/core/factory.py
index cefc2ff9e..49bfcab41 100644
--- a/src/poetry/core/factory.py
+++ b/src/poetry/core/factory.py
@@ -16,9 +16,9 @@
 
 
 if TYPE_CHECKING:
+    from poetry.core.packages.dependency import Dependency
     from poetry.core.packages.dependency_group import DependencyGroup
     from poetry.core.packages.project_package import ProjectPackage
-    from poetry.core.packages.types import DependencyTypes
     from poetry.core.poetry import Poetry
     from poetry.core.spdx.license import License
     from poetry.core.version.markers import BaseMarker
@@ -224,7 +224,7 @@ def create_dependency(
         constraint: DependencyConstraint,
         groups: list[str] | None = None,
         root_dir: Path | None = None,
-    ) -> DependencyTypes:
+    ) -> Dependency:
         from poetry.core.packages.constraints import (
             parse_constraint as parse_generic_constraint,
         )
diff --git a/src/poetry/core/packages/dependency_group.py b/src/poetry/core/packages/dependency_group.py
index 5839c109b..dfe36ca8e 100644
--- a/src/poetry/core/packages/dependency_group.py
+++ b/src/poetry/core/packages/dependency_group.py
@@ -4,27 +4,27 @@
 
 
 if TYPE_CHECKING:
-    from poetry.core.packages.types import DependencyTypes
+    from poetry.core.packages.dependency import Dependency
 
 
 class DependencyGroup:
     def __init__(self, name: str, optional: bool = False) -> None:
         self._name: str = name
         self._optional: bool = optional
-        self._dependencies: list[DependencyTypes] = []
+        self._dependencies: list[Dependency] = []
 
     @property
     def name(self) -> str:
         return self._name
 
     @property
-    def dependencies(self) -> list[DependencyTypes]:
+    def dependencies(self) -> list[Dependency]:
         return self._dependencies
 
     def is_optional(self) -> bool:
         return self._optional
 
-    def add_dependency(self, dependency: DependencyTypes) -> None:
+    def add_dependency(self, dependency: Dependency) -> None:
         self._dependencies.append(dependency)
 
     def remove_dependency(self, name: str) -> None:
diff --git a/src/poetry/core/packages/package.py b/src/poetry/core/packages/package.py
index 12f35b2ee..635e0d7f5 100644
--- a/src/poetry/core/packages/package.py
+++ b/src/poetry/core/packages/package.py
@@ -8,6 +8,7 @@
 from typing import TYPE_CHECKING
 from typing import Collection
 from typing import Iterable
+from typing import TypeVar
 
 from poetry.core.packages.specification import PackageSpecification
 from poetry.core.packages.utils.utils import create_nested_marker
@@ -16,8 +17,8 @@
 
 
 if TYPE_CHECKING:
+    from poetry.core.packages.dependency import Dependency
     from poetry.core.packages.dependency_group import DependencyGroup
-    from poetry.core.packages.types import DependencyTypes
     from poetry.core.semver.version import Version
     from poetry.core.semver.version_constraint import VersionConstraint
     from poetry.core.spdx.license import License
@@ -25,6 +26,8 @@
 
 AUTHOR_REGEX = re.compile(r"(?u)^(?P<name>[- .,\w\d'’\"()&]+)(?: <(?P<email>.+?)>)?$")
 
+T = TypeVar("T", bound="Package")
+
 
 class Package(PackageSpecification):
 
@@ -96,17 +99,17 @@ def __init__(
 
         # For compatibility with previous version, we keep the category
         self.category = "main"
-        self.files = []
+        self.files: list[dict[str, str]] = []
         self.optional = False
 
         self.classifiers = []
 
         self._python_versions = "*"
         self._python_constraint = parse_constraint("*")
-        self._python_marker = AnyMarker()
+        self._python_marker: BaseMarker = AnyMarker()
 
         self.platform = None
-        self.marker = AnyMarker()
+        self.marker: BaseMarker = AnyMarker()
 
         self.root_dir: Path | None = None
 
@@ -183,7 +186,7 @@ def maintainer_email(self) -> str:
         return self._get_maintainer()["email"]
 
     @property
-    def requires(self) -> list[DependencyTypes]:
+    def requires(self) -> list[Dependency]:
         """
         Returns the default dependencies
         """
@@ -195,7 +198,7 @@ def requires(self) -> list[DependencyTypes]:
     @property
     def all_requires(
         self,
-    ) -> list[DependencyTypes]:
+    ) -> list[Dependency]:
         """
         Returns the default dependencies and group dependencies.
         """
@@ -389,8 +392,8 @@ def dependency_group(self, name: str) -> DependencyGroup:
 
     def add_dependency(
         self,
-        dependency: DependencyTypes,
-    ) -> DependencyTypes:
+        dependency: Dependency,
+    ) -> Dependency:
         from poetry.core.packages.dependency_group import DependencyGroup
 
         for group_name in dependency.groups:
@@ -427,8 +430,8 @@ def without_optional_dependency_groups(self) -> Package:
         return package
 
     def with_dependency_groups(
-        self, groups: Collection[str], only: bool = False
-    ) -> Package:
+        self: T, groups: Collection[str], only: bool = False
+    ) -> T:
         """
         Returns a clone of the package with the given dependency groups opted in.
 
@@ -445,9 +448,7 @@ def with_dependency_groups(
 
         return package
 
-    def to_dependency(
-        self,
-    ) -> DependencyTypes:
+    def to_dependency(self) -> Dependency:
         from pathlib import Path
 
         from poetry.core.packages.dependency import Dependency
diff --git a/src/poetry/core/packages/project_package.py b/src/poetry/core/packages/project_package.py
index b36985e16..99a6e4e5e 100644
--- a/src/poetry/core/packages/project_package.py
+++ b/src/poetry/core/packages/project_package.py
@@ -8,8 +8,8 @@
 
 
 if TYPE_CHECKING:
-    from poetry.core.packages.types import DependencyTypes
-    from poetry.core.semver.version_constraint import VersionConstraint
+    from poetry.core.packages.dependency import Dependency
+    from poetry.core.semver.version import Version
 
 from poetry.core.packages.package import Package
 from poetry.core.packages.utils.utils import create_nested_marker
@@ -19,16 +19,16 @@ class ProjectPackage(Package):
     def __init__(
         self,
         name: str,
-        version: str | VersionConstraint,
+        version: str | Version,
         pretty_version: str | None = None,
     ) -> None:
         super().__init__(name, version, pretty_version)
 
-        self.build_config = {}
-        self.packages = []
-        self.include = []
-        self.exclude = []
-        self.custom_urls = {}
+        self.build_config: dict[str, Any] = {}
+        self.packages: list[dict[str, Any]] = []
+        self.include: list[dict[str, Any]] = []
+        self.exclude: list[dict[str, Any]] = []
+        self.custom_urls: dict[str, str] = {}
 
         if self._python_versions == "*":
             self._python_constraint = parse_constraint("~2.7 || >=3.4")
@@ -40,7 +40,7 @@ def build_script(self) -> str | None:
     def is_root(self) -> bool:
         return True
 
-    def to_dependency(self) -> DependencyTypes:
+    def to_dependency(self) -> Dependency:
         dependency = super().to_dependency()
 
         dependency.is_root = True
@@ -64,7 +64,7 @@ def python_versions(self, value: str) -> None:
         )
 
     @property
-    def urls(self) -> dict[str, Any]:
+    def urls(self) -> dict[str, str]:
         urls = super().urls
 
         urls.update(self.custom_urls)
diff --git a/src/poetry/core/packages/types.py b/src/poetry/core/packages/types.py
deleted file mode 100644
index 542706038..000000000
--- a/src/poetry/core/packages/types.py
+++ /dev/null
@@ -1,16 +0,0 @@
-from __future__ import annotations
-
-from typing import TYPE_CHECKING
-from typing import Union
-
-
-if TYPE_CHECKING:
-    from poetry.core.packages.dependency import Dependency
-    from poetry.core.packages.directory_dependency import DirectoryDependency
-    from poetry.core.packages.file_dependency import FileDependency
-    from poetry.core.packages.url_dependency import URLDependency
-    from poetry.core.packages.vcs_dependency import VCSDependency
-
-    DependencyTypes = Union[
-        Dependency, DirectoryDependency, FileDependency, URLDependency, VCSDependency
-    ]
diff --git a/src/poetry/core/py.typed b/src/poetry/core/py.typed
new file mode 100644
index 000000000..e69de29bb
diff --git a/src/poetry/core/pyproject/toml.py b/src/poetry/core/pyproject/toml.py
index a59e4c948..e0bc57713 100644
--- a/src/poetry/core/pyproject/toml.py
+++ b/src/poetry/core/pyproject/toml.py
@@ -8,7 +8,6 @@
     from pathlib import Path
 
     from tomlkit.container import Container
-    from tomlkit.items import Item
     from tomlkit.toml_document import TOMLDocument
 
     from poetry.core.pyproject.tables import BuildSystem
@@ -60,7 +59,7 @@ def build_system(self) -> BuildSystem:
         return self._build_system
 
     @property
-    def poetry_config(self) -> Item | Container:
+    def poetry_config(self) -> Container:
         from tomlkit.exceptions import NonExistentKey
 
         try:
diff --git a/src/poetry/core/semver/version.py b/src/poetry/core/semver/version.py
index 13fdf10a7..02ad436b1 100644
--- a/src/poetry/core/semver/version.py
+++ b/src/poetry/core/semver/version.py
@@ -77,7 +77,7 @@ def is_empty(self) -> bool:
     def is_simple(self) -> bool:
         return True
 
-    def allows(self, version: Version) -> bool:
+    def allows(self, version: Version | None) -> bool:
         if version is None:
             return False
 
diff --git a/src/poetry/core/semver/version_range.py b/src/poetry/core/semver/version_range.py
index 7e6e7d8bd..6b32d311b 100644
--- a/src/poetry/core/semver/version_range.py
+++ b/src/poetry/core/semver/version_range.py
@@ -39,15 +39,15 @@ def __init__(
         self._include_max = include_max
 
     @property
-    def min(self) -> Version:
+    def min(self) -> Version | None:
         return self._min
 
     @property
-    def max(self) -> Version:
+    def max(self) -> Version | None:
         return self._max
 
     @property
-    def full_max(self) -> Version:
+    def full_max(self) -> Version | None:
         return self._full_max
 
     @property
@@ -177,6 +177,7 @@ def intersect(self, other: VersionConstraint) -> VersionConstraint:
             # Because we already verified that the lower range isn't strictly
             # lower, there must be some overlap.
             assert intersect_include_min and intersect_include_max
+            assert intersect_min is not None
 
             return intersect_min
 
@@ -267,6 +268,7 @@ def difference(self, other: VersionConstraint) -> VersionConstraint:
             if not self.allows_any(other):
                 return self
 
+            before: VersionConstraint | None
             if not self.allows_lower(other):
                 before = None
             elif self.min == other.min:
@@ -276,6 +278,7 @@ def difference(self, other: VersionConstraint) -> VersionConstraint:
                     self.min, other.min, self.include_min, not other.include_min
                 )
 
+            after: VersionConstraint | None
             if not self.allows_higher(other):
                 after = None
             elif self.max == other.max:
@@ -289,6 +292,7 @@ def difference(self, other: VersionConstraint) -> VersionConstraint:
                 return EmptyConstraint()
 
             if before is None:
+                assert after is not None
                 return after
 
             if after is None:
diff --git a/src/poetry/core/semver/version_range_constraint.py b/src/poetry/core/semver/version_range_constraint.py
index 972e41e71..03a431c69 100644
--- a/src/poetry/core/semver/version_range_constraint.py
+++ b/src/poetry/core/semver/version_range_constraint.py
@@ -13,17 +13,17 @@
 class VersionRangeConstraint(VersionConstraint):
     @property
     @abstractmethod
-    def min(self) -> Version:
+    def min(self) -> Version | None:
         raise NotImplementedError()
 
     @property
     @abstractmethod
-    def max(self) -> Version:
+    def max(self) -> Version | None:
         raise NotImplementedError()
 
     @property
     @abstractmethod
-    def full_max(self) -> Version:
+    def full_max(self) -> Version | None:
         raise NotImplementedError()
 
     @property