diff --git a/sqlalchemy_utils/primitives/country.py b/sqlalchemy_utils/primitives/country.py
index bb67dead..47ac63dd 100644
--- a/sqlalchemy_utils/primitives/country.py
+++ b/sqlalchemy_utils/primitives/country.py
@@ -1,4 +1,7 @@
+from __future__ import annotations
+
 from functools import total_ordering
+from typing import Any, Union
 
 from .. import i18n
 from ..utils import str_coercible
@@ -52,7 +55,7 @@ class Country:
         assert hash(Country('FI')) == hash('FI')
 
     """
-    def __init__(self, code_or_country):
+    def __init__(self, code_or_country: Union[Country, str]) -> None:
         if isinstance(code_or_country, Country):
             self.code = code_or_country.code
         elif isinstance(code_or_country, str):
@@ -67,11 +70,11 @@ def __init__(self, code_or_country):
             )
 
     @property
-    def name(self):
+    def name(self) -> str:
         return i18n.get_locale().territories[self.code]
 
     @classmethod
-    def validate(self, code):
+    def validate(self, code: str) -> None:
         try:
             i18n.babel.Locale('en').territories[code]
         except KeyError:
@@ -82,7 +85,7 @@ def validate(self, code):
             # As babel is optional, we may raise an AttributeError accessing it
             pass
 
-    def __eq__(self, other):
+    def __eq__(self, other: Any) -> bool:
         if isinstance(other, Country):
             return self.code == other.code
         elif isinstance(other, str):
@@ -90,13 +93,13 @@ def __eq__(self, other):
         else:
             return NotImplemented
 
-    def __hash__(self):
+    def __hash__(self) -> int:
         return hash(self.code)
 
-    def __ne__(self, other):
+    def __ne__(self, other: Any) -> bool:
         return not (self == other)
 
-    def __lt__(self, other):
+    def __lt__(self, other: Union[Country, str]) -> bool:
         if isinstance(other, Country):
             return self.code < other.code
         elif isinstance(other, str):
@@ -106,5 +109,5 @@ def __lt__(self, other):
     def __repr__(self):
         return f'{self.__class__.__name__}({self.code!r})'
 
-    def __unicode__(self):
+    def __unicode__(self) -> str:
         return self.name
diff --git a/sqlalchemy_utils/primitives/currency.py b/sqlalchemy_utils/primitives/currency.py
index ef8d46ad..76fe9380 100644
--- a/sqlalchemy_utils/primitives/currency.py
+++ b/sqlalchemy_utils/primitives/currency.py
@@ -1,3 +1,7 @@
+from __future__ import annotations
+
+from typing import Any, Union
+
 from .. import i18n, ImproperlyConfigured
 from ..utils import str_coercible
 
@@ -50,7 +54,7 @@ class Currency:
 
 
     """
-    def __init__(self, code):
+    def __init__(self, code: Union[Currency, str]) -> None:
         if i18n.babel is None:
             raise ImproperlyConfigured(
                 "'babel' package is required in order to use Currency class."
@@ -68,7 +72,7 @@ def __init__(self, code):
             )
 
     @classmethod
-    def validate(self, code):
+    def validate(self, code: str) -> None:
         try:
             i18n.babel.Locale('en').currencies[code]
         except KeyError:
@@ -78,17 +82,17 @@ def validate(self, code):
             pass
 
     @property
-    def symbol(self):
+    def symbol(self) -> str:
         return i18n.babel.numbers.get_currency_symbol(
             self.code,
             i18n.get_locale()
         )
 
     @property
-    def name(self):
+    def name(self) -> str:
         return i18n.get_locale().currencies[self.code]
 
-    def __eq__(self, other):
+    def __eq__(self, other: Any) -> bool:
         if isinstance(other, Currency):
             return self.code == other.code
         elif isinstance(other, str):
@@ -96,14 +100,14 @@ def __eq__(self, other):
         else:
             return NotImplemented
 
-    def __ne__(self, other):
+    def __ne__(self, other: Any) -> bool:
         return not (self == other)
 
-    def __hash__(self):
+    def __hash__(self) -> int:
         return hash(self.code)
 
     def __repr__(self):
         return f'{self.__class__.__name__}({self.code!r})'
 
-    def __unicode__(self):
+    def __unicode__(self) -> str:
         return self.code
diff --git a/sqlalchemy_utils/primitives/ltree.py b/sqlalchemy_utils/primitives/ltree.py
index db7e42fe..51204c56 100644
--- a/sqlalchemy_utils/primitives/ltree.py
+++ b/sqlalchemy_utils/primitives/ltree.py
@@ -1,8 +1,11 @@
+from __future__ import annotations
+
 import re
+from typing import Any, Iterable, Optional, Union
 
 from ..utils import str_coercible
 
-path_matcher = re.compile(r'^[A-Za-z0-9_]+(\.[A-Za-z0-9_]+)*$')
+path_matcher: re.Pattern = re.compile(r'^[A-Za-z0-9_]+(\.[A-Za-z0-9_]+)*$')
 
 
 @str_coercible
@@ -92,7 +95,7 @@ class Ltree:
         assert Ltree('1.2') + Ltree('1.2') == Ltree('1.2.1.2')
     """
 
-    def __init__(self, path_or_ltree):
+    def __init__(self, path_or_ltree: Union[Ltree, str]) -> None:
         if isinstance(path_or_ltree, Ltree):
             self.path = path_or_ltree.path
         elif isinstance(path_or_ltree, str):
@@ -107,16 +110,16 @@ def __init__(self, path_or_ltree):
             )
 
     @classmethod
-    def validate(cls, path):
+    def validate(cls, path: str) -> None:
         if path_matcher.match(path) is None:
             raise ValueError(
                 f"'{path}' is not a valid ltree path."
             )
 
-    def __len__(self):
+    def __len__(self) -> int:
         return len(self.path.split('.'))
 
-    def index(self, other):
+    def index(self, other: Union[Ltree, str]) -> int:
         subpath = Ltree(other).path.split('.')
         parts = self.path.split('.')
         for index, _ in enumerate(parts):
@@ -124,7 +127,7 @@ def index(self, other):
                 return index
         raise ValueError('subpath not found')
 
-    def descendant_of(self, other):
+    def descendant_of(self, other: Union[Ltree, str]) -> bool:
         """
         is left argument a descendant of right (or equal)?
 
@@ -135,7 +138,7 @@ def descendant_of(self, other):
         subpath = self[:len(Ltree(other))]
         return subpath == other
 
-    def ancestor_of(self, other):
+    def ancestor_of(self, other: Union[Ltree, str]) -> bool:
         """
         is left argument an ancestor of right (or equal)?
 
@@ -146,7 +149,7 @@ def ancestor_of(self, other):
         subpath = Ltree(other)[:len(self)]
         return subpath == self
 
-    def __getitem__(self, key):
+    def __getitem__(self, key: Union[int, slice]) -> Ltree:
         if isinstance(key, int):
             return Ltree(self.path.split('.')[key])
         elif isinstance(key, slice):
@@ -157,7 +160,7 @@ def __getitem__(self, key):
             )
         )
 
-    def lca(self, *others):
+    def lca(self, *others: Union[Ltree, str]) -> Optional[Ltree]:
         """
         Lowest common ancestor, i.e., longest common prefix of paths
 
@@ -178,13 +181,13 @@ def lca(self, *others):
                     return None
                 return Ltree('.'.join(parts[0:index]))
 
-    def __add__(self, other):
+    def __add__(self, other: Union[Ltree, str]) -> Ltree:
         return Ltree(self.path + '.' + Ltree(other).path)
 
-    def __radd__(self, other):
+    def __radd__(self, other: Union[Ltree, str]) -> Ltree:
         return Ltree(other) + self
 
-    def __eq__(self, other):
+    def __eq__(self, other: Any) -> bool:
         if isinstance(other, Ltree):
             return self.path == other.path
         elif isinstance(other, str):
@@ -192,19 +195,19 @@ def __eq__(self, other):
         else:
             return NotImplemented
 
-    def __hash__(self):
+    def __hash__(self) -> int:
         return hash(self.path)
 
-    def __ne__(self, other):
+    def __ne__(self, other: Any) -> bool:
         return not (self == other)
 
     def __repr__(self):
         return f'{self.__class__.__name__}({self.path!r})'
 
-    def __unicode__(self):
+    def __unicode__(self) -> str:
         return self.path
 
-    def __contains__(self, label):
+    def __contains__(self, label: Iterable) -> bool:
         return label in self.path.split('.')
 
     def __gt__(self, other):
diff --git a/sqlalchemy_utils/primitives/weekday.py b/sqlalchemy_utils/primitives/weekday.py
index 21038940..9ebed010 100644
--- a/sqlalchemy_utils/primitives/weekday.py
+++ b/sqlalchemy_utils/primitives/weekday.py
@@ -1,4 +1,7 @@
+from __future__ import annotations
+
 from functools import total_ordering
+from typing import Any
 
 from .. import i18n
 from ..utils import str_coercible
@@ -7,34 +10,34 @@
 @str_coercible
 @total_ordering
 class WeekDay:
-    NUM_WEEK_DAYS = 7
+    NUM_WEEK_DAYS: int = 7
 
-    def __init__(self, index):
+    def __init__(self, index: int) -> None:
         if not (0 <= index < self.NUM_WEEK_DAYS):
             raise ValueError(
                 "index must be between 0 and %d" % self.NUM_WEEK_DAYS
             )
         self.index = index
 
-    def __eq__(self, other):
+    def __eq__(self, other: Any) -> bool:
         if isinstance(other, WeekDay):
             return self.index == other.index
         else:
             return NotImplemented
 
-    def __hash__(self):
+    def __hash__(self) -> int:
         return hash(self.index)
 
-    def __lt__(self, other):
+    def __lt__(self, other: WeekDay) -> bool:
         return self.position < other.position
 
     def __repr__(self):
         return f'{self.__class__.__name__}({self.index!r})'
 
-    def __unicode__(self):
+    def __unicode__(self) -> str:
         return self.name
 
-    def get_name(self, width='wide', context='format'):
+    def get_name(self, width: str = 'wide', context: str = 'format') -> str:
         names = i18n.babel.dates.get_day_names(
             width,
             context,
@@ -43,11 +46,11 @@ def get_name(self, width='wide', context='format'):
         return names[self.index]
 
     @property
-    def name(self):
+    def name(self) -> str:
         return self.get_name()
 
     @property
-    def position(self):
+    def position(self) -> int:
         return (
             self.index -
             i18n.get_locale().first_week_day
diff --git a/sqlalchemy_utils/primitives/weekdays.py b/sqlalchemy_utils/primitives/weekdays.py
index a21a4df7..88aca36d 100644
--- a/sqlalchemy_utils/primitives/weekdays.py
+++ b/sqlalchemy_utils/primitives/weekdays.py
@@ -1,10 +1,16 @@
+from __future__ import annotations
+
+from typing import Any, Generator, Hashable, Union
+
 from ..utils import str_coercible
 from .weekday import WeekDay
 
 
 @str_coercible
 class WeekDays:
-    def __init__(self, bit_string_or_week_days):
+    _days: set
+
+    def __init__(self, bit_string_or_week_days: Union[str, WeekDays, Hashable]) -> None:
         if isinstance(bit_string_or_week_days, str):
             self._days = set()
 
@@ -27,7 +33,7 @@ def __init__(self, bit_string_or_week_days):
         else:
             self._days = set(bit_string_or_week_days)
 
-    def __eq__(self, other):
+    def __eq__(self, other: Any) -> bool:
         if isinstance(other, WeekDays):
             return self._days == other._days
         elif isinstance(other, str):
@@ -35,22 +41,23 @@ def __eq__(self, other):
         else:
             return NotImplemented
 
-    def __iter__(self):
-        yield from sorted(self._days)
+    def __iter__(self) -> Generator[WeekDay, None, None]:
+        for day in sorted(self._days):
+            yield day
 
-    def __contains__(self, value):
+    def __contains__(self, value: Any) -> bool:
         return value in self._days
 
-    def __repr__(self):
-        return '{}({!r})'.format(
+    def __repr__(self) -> str:
+        return '%s(%r)' % (
             self.__class__.__name__,
             self.as_bit_string()
         )
 
-    def __unicode__(self):
+    def __unicode__(self) -> str:
         return ', '.join(str(day) for day in self)
 
-    def as_bit_string(self):
+    def as_bit_string(self) -> str:
         return ''.join(
             '1' if WeekDay(index) in self._days else '0'
             for index in range(WeekDay.NUM_WEEK_DAYS)