diff --git a/xdsl/dialects/memref_stream.py b/xdsl/dialects/memref_stream.py
index 2872d469b0..0f8caaedc0 100644
--- a/xdsl/dialects/memref_stream.py
+++ b/xdsl/dialects/memref_stream.py
@@ -10,9 +10,9 @@
 from collections.abc import Iterator, Sequence
 from enum import auto
 from itertools import product
-from typing import Any, ClassVar, Generic, TypeVar, cast
+from typing import Any, ClassVar, Generic, cast
 
-from typing_extensions import Self
+from typing_extensions import Self, TypeVar
 
 from xdsl.dialects import memref
 from xdsl.dialects.builtin import (
@@ -39,7 +39,6 @@
 from xdsl.irdl import (
     AnyAttr,
     AttrSizedOperandSegments,
-    BaseAttr,
     GenericAttrConstraint,
     IRDLOperation,
     ParamAttrConstraint,
@@ -66,8 +65,9 @@
 from xdsl.utils.hints import isa
 from xdsl.utils.str_enum import StrEnum
 
-_StreamTypeElement = TypeVar("_StreamTypeElement", bound=Attribute, covariant=True)
-_StreamTypeElementConstrT = TypeVar("_StreamTypeElementConstrT", bound=Attribute)
+_StreamTypeElement = TypeVar(
+    "_StreamTypeElement", bound=Attribute, covariant=True, default=Attribute
+)
 
 
 @irdl_attr_definition
@@ -87,20 +87,16 @@ def get_element_type(self) -> _StreamTypeElement:
     def __init__(self, element_type: _StreamTypeElement):
         super().__init__([element_type])
 
-    @staticmethod
+    @classmethod
     def constr(
-        element_type: GenericAttrConstraint[_StreamTypeElementConstrT],
-    ) -> ParamAttrConstraint[ReadableStreamType[_StreamTypeElementConstrT]]:
-        return ParamAttrConstraint[ReadableStreamType[_StreamTypeElementConstrT]](
+        cls,
+        element_type: GenericAttrConstraint[_StreamTypeElement] = AnyAttr(),
+    ) -> ParamAttrConstraint[ReadableStreamType[_StreamTypeElement]]:
+        return ParamAttrConstraint[ReadableStreamType[_StreamTypeElement]](
             ReadableStreamType, (element_type,)
         )
 
 
-AnyReadableStreamTypeConstr = BaseAttr[ReadableStreamType[Attribute]](
-    ReadableStreamType
-)
-
-
 @irdl_attr_definition
 class WritableStreamType(
     Generic[_StreamTypeElement],
@@ -118,20 +114,16 @@ def get_element_type(self) -> _StreamTypeElement:
     def __init__(self, element_type: _StreamTypeElement):
         super().__init__([element_type])
 
-    @staticmethod
+    @classmethod
     def constr(
-        element_type: GenericAttrConstraint[_StreamTypeElementConstrT],
-    ) -> ParamAttrConstraint[WritableStreamType[_StreamTypeElementConstrT]]:
-        return ParamAttrConstraint[WritableStreamType[_StreamTypeElementConstrT]](
+        cls,
+        element_type: GenericAttrConstraint[_StreamTypeElement] = AnyAttr(),
+    ) -> ParamAttrConstraint[WritableStreamType[_StreamTypeElement]]:
+        return ParamAttrConstraint[WritableStreamType[_StreamTypeElement]](
             WritableStreamType, (element_type,)
         )
 
 
-AnyWritableStreamTypeConstr = BaseAttr[WritableStreamType[Attribute]](
-    WritableStreamType
-)
-
-
 class IteratorType(StrEnum):
     "Iterator type for memref_stream Attribute"
 
@@ -471,7 +463,7 @@ class GenericOp(IRDLOperation):
     Pointers to memory buffers or streams to be operated on. The corresponding stride
     pattern defines the order in which the elements of the input buffers will be read.
     """
-    outputs = var_operand_def(AnyMemRefTypeConstr | AnyWritableStreamTypeConstr)
+    outputs = var_operand_def(AnyMemRefTypeConstr | WritableStreamType.constr())
     """
     Pointers to memory buffers or streams to be operated on. The corresponding stride
     pattern defines the order in which the elements of the input buffers will be written
diff --git a/xdsl/dialects/snitch.py b/xdsl/dialects/snitch.py
index 37309e0f99..5a89c793a7 100644
--- a/xdsl/dialects/snitch.py
+++ b/xdsl/dialects/snitch.py
@@ -13,7 +13,9 @@
 from abc import ABC
 from collections.abc import Sequence
 from dataclasses import dataclass
-from typing import Generic, TypeVar
+from typing import Generic
+
+from typing_extensions import TypeVar
 
 from xdsl.dialects.builtin import ContainerType, IntAttr
 from xdsl.dialects.riscv import IntRegisterType
@@ -26,7 +28,7 @@
     TypeAttribute,
 )
 from xdsl.irdl import (
-    BaseAttr,
+    AnyAttr,
     GenericAttrConstraint,
     IRDLOperation,
     ParamAttrConstraint,
@@ -39,8 +41,9 @@
 )
 from xdsl.utils.exceptions import VerifyException
 
-_StreamTypeElement = TypeVar("_StreamTypeElement", bound=Attribute, covariant=True)
-_StreamTypeElementConstrT = TypeVar("_StreamTypeElementConstrT", bound=Attribute)
+_StreamTypeElement = TypeVar(
+    "_StreamTypeElement", bound=Attribute, covariant=True, default=Attribute
+)
 
 
 @irdl_attr_definition
@@ -60,20 +63,16 @@ def get_element_type(self) -> _StreamTypeElement:
     def __init__(self, element_type: _StreamTypeElement):
         super().__init__([element_type])
 
-    @staticmethod
+    @classmethod
     def constr(
-        element_type: GenericAttrConstraint[_StreamTypeElementConstrT],
-    ) -> ParamAttrConstraint[ReadableStreamType[_StreamTypeElementConstrT]]:
-        return ParamAttrConstraint[ReadableStreamType[_StreamTypeElementConstrT]](
+        cls,
+        element_type: GenericAttrConstraint[_StreamTypeElement] = AnyAttr(),
+    ) -> ParamAttrConstraint[ReadableStreamType[_StreamTypeElement]]:
+        return ParamAttrConstraint[ReadableStreamType[_StreamTypeElement]](
             ReadableStreamType, (element_type,)
         )
 
 
-AnyReadableStreamTypeConstr = BaseAttr[ReadableStreamType[Attribute]](
-    ReadableStreamType
-)
-
-
 @irdl_attr_definition
 class WritableStreamType(
     Generic[_StreamTypeElement],
@@ -91,20 +90,16 @@ def get_element_type(self) -> _StreamTypeElement:
     def __init__(self, element_type: _StreamTypeElement):
         super().__init__([element_type])
 
-    @staticmethod
+    @classmethod
     def constr(
-        element_type: GenericAttrConstraint[_StreamTypeElementConstrT],
-    ) -> ParamAttrConstraint[WritableStreamType[_StreamTypeElementConstrT]]:
-        return ParamAttrConstraint[WritableStreamType[_StreamTypeElementConstrT]](
+        cls,
+        element_type: GenericAttrConstraint[_StreamTypeElement] = AnyAttr(),
+    ) -> ParamAttrConstraint[WritableStreamType[_StreamTypeElement]]:
+        return ParamAttrConstraint[WritableStreamType[_StreamTypeElement]](
             WritableStreamType, (element_type,)
         )
 
 
-AnyWritableStreamTypeConstr = BaseAttr[WritableStreamType[Attribute]](
-    WritableStreamType
-)
-
-
 @dataclass(frozen=True)
 class SnitchResources:
     """
@@ -222,7 +217,7 @@ class SsrEnableOp(IRDLOperation):
 
     name = "snitch.ssr_enable"
 
-    streams = var_result_def(AnyReadableStreamTypeConstr | AnyWritableStreamTypeConstr)
+    streams = var_result_def(ReadableStreamType.constr() | WritableStreamType.constr())
 
     def __init__(self, stream_types: Sequence[Attribute]):
         super().__init__(result_types=[stream_types])