Replace type_workarounds.NotImplementedType with types.NotImplemented…

…Type (#6790)

- Replaced type_workarounds.NotImplementedType with types.NotImplementedType,
  removing the need for the type_workarounds module.

- This change simplifies the codebase by relying on standard types,
  allowing us to delete the now-redundant type_workarounds.py file.

Fixes #6775

cirq-core/cirq/__init__.py

@@ -26,7 +26,6 @@
     # Low level
     _version,
     _doc,
-    type_workarounds,
 )
 
 with _import.delay_import('cirq.protocols'):

cirq-core/cirq/circuits/circuit.py

@@ -25,6 +25,7 @@
 import itertools
 import math
 from collections import defaultdict
+from types import NotImplementedType
 from typing import (
     AbstractSet,
     Any,
@@ -62,7 +63,6 @@
 from cirq.circuits.qasm_output import QasmOutput
 from cirq.circuits.text_diagram_drawer import TextDiagramDrawer
 from cirq.protocols import circuit_diagram_info_protocol
-from cirq.type_workarounds import NotImplementedType
 
 if TYPE_CHECKING:
     import cirq

cirq-core/cirq/circuits/frozen_circuit.py

@@ -13,6 +13,7 @@
 # limitations under the License.
 """An immutable version of the Circuit data structure."""
 from functools import cached_property
+from types import NotImplementedType
 from typing import (
     AbstractSet,
     FrozenSet,
@@ -30,7 +31,6 @@
 from cirq import protocols, _compat
 from cirq.circuits import AbstractCircuit, Alignment, Circuit
 from cirq.circuits.insert_strategy import InsertStrategy
-from cirq.type_workarounds import NotImplementedType
 
 if TYPE_CHECKING:
     import cirq

cirq-core/cirq/circuits/moment.py

@@ -15,6 +15,7 @@
 """A simplified time-slice of operations within a sequenced circuit."""
 
 import itertools
+from types import NotImplementedType
 from typing import (
     AbstractSet,
     Any,
@@ -33,6 +34,7 @@
     TYPE_CHECKING,
     Union,
 )
+
 from typing_extensions import Self
 
 import numpy as np
@@ -41,7 +43,6 @@
 from cirq._import import LazyLoader
 from cirq.ops import raw_types, op_tree
 from cirq.protocols import circuit_diagram_info_protocol
-from cirq.type_workarounds import NotImplementedType
 
 if TYPE_CHECKING:
     import cirq

cirq-core/cirq/contrib/acquaintance/permutation.py

@@ -13,6 +13,7 @@
 # limitations under the License.
 
 import abc
+from types import NotImplementedType
 from typing import (
     Any,
     cast,
@@ -28,7 +29,6 @@
 )
 
 from cirq import circuits, ops, protocols, transformers, value
-from cirq.type_workarounds import NotImplementedType
 
 if TYPE_CHECKING:
     import cirq

cirq-core/cirq/contrib/paulistring/clifford_target_gateset.py

@@ -12,12 +12,13 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+from types import NotImplementedType
 from typing import List, Union, Type, cast, TYPE_CHECKING
 from enum import Enum
+
 import numpy as np
 
 from cirq import ops, transformers, protocols, linalg
-from cirq.type_workarounds import NotImplementedType
 
 if TYPE_CHECKING:
     import cirq

cirq-core/cirq/ops/clifford_gate.py

@@ -12,18 +12,18 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from typing import Any, Dict, List, Optional, Sequence, Tuple, TYPE_CHECKING, Union
-
 import functools
 from dataclasses import dataclass
+from types import NotImplementedType
+from typing import Any, Dict, List, Optional, Sequence, Tuple, TYPE_CHECKING, Union
+
 import numpy as np
 
 from cirq import protocols, value, linalg, qis
 from cirq._import import LazyLoader
 from cirq._compat import cached_method
 from cirq.ops import common_gates, named_qubit, raw_types, pauli_gates, phased_x_z_gate
 from cirq.ops.pauli_gates import Pauli
-from cirq.type_workarounds import NotImplementedType
 
 if TYPE_CHECKING:
     import cirq

cirq-core/cirq/ops/common_gates.py

@@ -25,6 +25,7 @@
 raised to a power (i.e. cirq.H**0.5). See the definition in EigenGate.
 """
 
+from types import NotImplementedType
 from typing import (
     Any,
     cast,
@@ -46,9 +47,6 @@
 from cirq._compat import proper_repr
 from cirq._doc import document
 from cirq.ops import controlled_gate, eigen_gate, gate_features, raw_types, control_values as cv
-
-from cirq.type_workarounds import NotImplementedType
-
 from cirq.ops.swap_gates import ISWAP, SWAP, ISwapPowGate, SwapPowGate
 from cirq.ops.measurement_gate import MeasurementGate
 

cirq-core/cirq/ops/controlled_gate.py

@@ -12,6 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+from types import NotImplementedType
 from typing import (
     AbstractSet,
     Any,
@@ -35,7 +36,6 @@
     matrix_gates,
     control_values as cv,
 )
-from cirq.type_workarounds import NotImplementedType
 
 if TYPE_CHECKING:
     import cirq
@@ -255,7 +255,7 @@ def _unitary_(self) -> Union[np.ndarray, NotImplementedType]:
     def _has_mixture_(self) -> bool:
         return protocols.has_mixture(self.sub_gate)
 
-    def _mixture_(self) -> Union[np.ndarray, NotImplementedType]:
+    def _mixture_(self) -> Union[Sequence[tuple[float, np.ndarray]], NotImplementedType]:
         qubits = line_qubit.LineQid.for_gate(self)
         op = self.sub_gate.on(*qubits[self.num_controls() :])
         c_op = cop.ControlledOperation(qubits[: self.num_controls()], op, self.control_values)

cirq-core/cirq/ops/controlled_gate_test.py

@@ -12,14 +12,14 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+from types import NotImplementedType
 from typing import Union, Tuple, cast
 
 import numpy as np
 import pytest
 import sympy
 
 import cirq
-from cirq.type_workarounds import NotImplementedType
 
 
 class GateUsingWorkspaceForApplyUnitary(cirq.testing.SingleQubitGate):

cirq-core/cirq/ops/controlled_operation.py

@@ -12,6 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+from types import NotImplementedType
 from typing import (
     AbstractSet,
     Any,
@@ -38,7 +39,6 @@
     raw_types,
     control_values as cv,
 )
-from cirq.type_workarounds import NotImplementedType
 
 if TYPE_CHECKING:
     import cirq

cirq-core/cirq/ops/controlled_operation_test.py

@@ -14,6 +14,7 @@
 
 import itertools
 import re
+from types import NotImplementedType
 from typing import cast, Tuple, Union
 
 import numpy as np
@@ -22,7 +23,6 @@
 
 import cirq
 from cirq import protocols
-from cirq.type_workarounds import NotImplementedType
 
 
 class GateUsingWorkspaceForApplyUnitary(cirq.testing.SingleQubitGate):

cirq-core/cirq/ops/dense_pauli_string.py

@@ -14,6 +14,7 @@
 
 import abc
 import numbers
+from types import NotImplementedType
 from typing import (
     AbstractSet,
     Any,
@@ -38,7 +39,6 @@
 from cirq import protocols, linalg, value
 from cirq._compat import proper_repr
 from cirq.ops import raw_types, identity, pauli_gates, global_phase_op, pauli_string
-from cirq.type_workarounds import NotImplementedType
 
 if TYPE_CHECKING:
     import cirq

cirq-core/cirq/ops/eigen_gate.py

@@ -15,6 +15,7 @@
 import fractions
 import math
 import numbers
+from types import NotImplementedType
 from typing import (
     AbstractSet,
     Any,
@@ -35,7 +36,6 @@
 from cirq import value, protocols
 from cirq.linalg import tolerance
 from cirq.ops import raw_types
-from cirq.type_workarounds import NotImplementedType
 
 if TYPE_CHECKING:
     import cirq

cirq-core/cirq/ops/gate_operation.py

@@ -16,6 +16,7 @@
 
 import re
 import warnings
+from types import NotImplementedType
 from typing import (
     AbstractSet,
     Any,
@@ -38,7 +39,6 @@
 
 from cirq import ops, protocols, value
 from cirq.ops import raw_types, gate_features, control_values as cv
-from cirq.type_workarounds import NotImplementedType
 
 if TYPE_CHECKING:
     import cirq

cirq-core/cirq/ops/global_phase_op.py

@@ -13,6 +13,7 @@
 # limitations under the License.
 """A no-qubit global phase operation."""
 
+from types import NotImplementedType
 from typing import AbstractSet, Any, cast, Dict, Sequence, Tuple, Union, Optional, Collection
 
 import numpy as np
@@ -21,7 +22,6 @@
 import cirq
 from cirq import value, protocols
 from cirq.ops import raw_types, controlled_gate, control_values as cv
-from cirq.type_workarounds import NotImplementedType
 
 
 @value.value_equality(approximate=True)

cirq-core/cirq/ops/identity.py

@@ -13,14 +13,14 @@
 # limitations under the License.
 """IdentityGate."""
 
+from types import NotImplementedType
 from typing import Any, Dict, Optional, Tuple, TYPE_CHECKING, Sequence, Union
 
 import numpy as np
 import sympy
 
 from cirq import protocols, value
 from cirq._doc import document
-from cirq.type_workarounds import NotImplementedType
 from cirq.ops import raw_types
 
 if TYPE_CHECKING:

cirq-core/cirq/ops/parallel_gate.py

@@ -12,14 +12,13 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-
+from types import NotImplementedType
 from typing import AbstractSet, Union, Any, Optional, Tuple, TYPE_CHECKING, Dict
 
 import numpy as np
 
 from cirq import protocols, value
 from cirq.ops import raw_types
-from cirq.type_workarounds import NotImplementedType
 
 if TYPE_CHECKING:
     import cirq

cirq-core/cirq/ops/pauli_gates.py

@@ -12,12 +12,12 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 import abc
+from types import NotImplementedType
 from typing import Any, cast, Tuple, TYPE_CHECKING, Union, Dict
 
 from cirq._doc import document
 from cirq._import import LazyLoader
 from cirq.ops import common_gates, raw_types, identity
-from cirq.type_workarounds import NotImplementedType
 
 
 if TYPE_CHECKING:

cirq-core/cirq/ops/pauli_string.py

@@ -14,6 +14,7 @@
 import cmath
 import math
 import numbers
+from types import NotImplementedType
 from typing import (
     Any,
     cast,
@@ -56,7 +57,6 @@
     pauli_interaction_gate,
     raw_types,
 )
-from cirq.type_workarounds import NotImplementedType
 
 if TYPE_CHECKING:
     import cirq

cirq-core/cirq/ops/phased_x_gate.py

@@ -12,18 +12,20 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 """An `XPowGate` conjugated by `ZPowGate`s."""
+
+from types import NotImplementedType
 from typing import AbstractSet, Any, cast, Dict, Optional, Sequence, Tuple, Union
 
 import math
 import numbers
+
 import numpy as np
 import sympy
 
 import cirq
 from cirq import value, protocols
 from cirq._compat import proper_repr
 from cirq.ops import common_gates, raw_types
-from cirq.type_workarounds import NotImplementedType
 
 
 @value.value_equality(manual_cls=True, approximate=True)
@@ -130,7 +132,7 @@ def _trace_distance_bound_(self) -> Optional[float]:
     def _has_unitary_(self):
         return not self._is_parameterized_()
 
-    def _unitary_(self) -> Union[np.ndarray, NotImplementedType]:
+    def _unitary_(self) -> Optional[Union[np.ndarray, NotImplementedType]]:
         """See `cirq.SupportsUnitary`."""
         if self._is_parameterized_():
             return None

cirq-core/cirq/ops/raw_types.py

@@ -16,6 +16,7 @@
 
 import abc
 import functools
+from types import NotImplementedType
 from typing import (
     cast,
     AbstractSet,
@@ -42,7 +43,6 @@
 from cirq import protocols, value
 from cirq._import import LazyLoader
 from cirq._compat import __cirq_debug__, _method_cache_name, cached_method
-from cirq.type_workarounds import NotImplementedType
 from cirq.ops import control_values as cv
 
 # Lazy imports to break circular dependencies.
@@ -879,7 +879,7 @@ def _mixture_(self) -> Sequence[Tuple[float, Any]]:
     def _has_kraus_(self) -> bool:
         return protocols.has_kraus(self.sub_operation)
 
-    def _kraus_(self) -> Union[Tuple[np.ndarray], NotImplementedType]:
+    def _kraus_(self) -> Union[Tuple[np.ndarray, ...], NotImplementedType]:
         return protocols.kraus(self.sub_operation, NotImplemented)
 
     @cached_method