From eeb4c50880c599efb35e477b26123b2e635d4c4e Mon Sep 17 00:00:00 2001
From: CalMacCQ <93673602+CalMacCQ@users.noreply.github.com>
Date: Mon, 27 Oct 2025 10:46:41 +0000
Subject: [PATCH 01/34] Agustin's suggested Protocol class

---
 hugr-py/src/hugr/hugr/pass.py | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)
 create mode 100644 hugr-py/src/hugr/hugr/pass.py

diff --git a/hugr-py/src/hugr/hugr/pass.py b/hugr-py/src/hugr/hugr/pass.py
new file mode 100644
index 0000000000..b9d0ec67ff
--- /dev/null
+++ b/hugr-py/src/hugr/hugr/pass.py
@@ -0,0 +1,16 @@
+from typing import Protocol, Self
+from hugr.hugr.base import Hugr
+
+
+class ComposablePass(Protocol):
+    def __call__(self, hugr: Hugr) -> None: ...
+
+    def then(self, other: Self) -> Self: ...
+
+    def with_entrypoint(self) -> Self: ...
+
+    @property
+    def is_global(self) -> bool: ...
+
+    @property
+    def is_recursive(self) -> bool: ...

From c5cf1d7f6657caaf76b7b46e7210cd7cb19b532d Mon Sep 17 00:00:00 2001
From: CalMacCQ <93673602+CalMacCQ@users.noreply.github.com>
Date: Mon, 27 Oct 2025 10:50:29 +0000
Subject: [PATCH 02/34] minor fixes

---
 hugr-py/src/hugr/hugr/pass.py | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/hugr-py/src/hugr/hugr/pass.py b/hugr-py/src/hugr/hugr/pass.py
index b9d0ec67ff..82d419827a 100644
--- a/hugr-py/src/hugr/hugr/pass.py
+++ b/hugr-py/src/hugr/hugr/pass.py
@@ -1,13 +1,19 @@
+"""A Protocol for a composable pass."""
+
 from typing import Protocol, Self
+
 from hugr.hugr.base import Hugr
+from hugr.node_port import Node
 
 
 class ComposablePass(Protocol):
+    """A Protocol which represents a composable Hugr transformation."""
+
     def __call__(self, hugr: Hugr) -> None: ...
 
     def then(self, other: Self) -> Self: ...
 
-    def with_entrypoint(self) -> Self: ...
+    def with_entrypoint(self, node: Node) -> Self: ...
 
     @property
     def is_global(self) -> bool: ...

From 8a3d6baa08085298d6aff32b3a16ff05b5d53af7 Mon Sep 17 00:00:00 2001
From: CalMacCQ <93673602+CalMacCQ@users.noreply.github.com>
Date: Mon, 27 Oct 2025 10:57:31 +0000
Subject: [PATCH 03/34] more methods

---
 hugr-py/src/hugr/hugr/pass.py | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/hugr-py/src/hugr/hugr/pass.py b/hugr-py/src/hugr/hugr/pass.py
index 82d419827a..14c8e74705 100644
--- a/hugr-py/src/hugr/hugr/pass.py
+++ b/hugr-py/src/hugr/hugr/pass.py
@@ -4,6 +4,7 @@
 
 from hugr.hugr.base import Hugr
 from hugr.node_port import Node
+from hugr.ops import Op
 
 
 class ComposablePass(Protocol):
@@ -15,6 +16,14 @@ def then(self, other: Self) -> Self: ...
 
     def with_entrypoint(self, node: Node) -> Self: ...
 
+    @classmethod
+    def from_dict(cls, dictionary: dict) -> Self: ...
+
+    def to_dict(self) -> dict: ...
+
+    @property
+    def supported_ops(self) -> set[Op]: ...
+
     @property
     def is_global(self) -> bool: ...
 

From 7b58c056a62c79fa8d7ae14c76cef00748a920a6 Mon Sep 17 00:00:00 2001
From: CalMacCQ <93673602+CalMacCQ@users.noreply.github.com>
Date: Mon, 27 Oct 2025 11:33:50 +0000
Subject: [PATCH 04/34] import Self from typing_extensions

---
 hugr-py/src/hugr/hugr/pass.py | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/hugr-py/src/hugr/hugr/pass.py b/hugr-py/src/hugr/hugr/pass.py
index 14c8e74705..c26cd01344 100644
--- a/hugr-py/src/hugr/hugr/pass.py
+++ b/hugr-py/src/hugr/hugr/pass.py
@@ -1,6 +1,8 @@
 """A Protocol for a composable pass."""
 
-from typing import Protocol, Self
+from typing import Protocol
+
+from typing_extensions import Self
 
 from hugr.hugr.base import Hugr
 from hugr.node_port import Node

From 5e31a3d785f771ebf80e832364dbe22761c9cedd Mon Sep 17 00:00:00 2001
From: CalMacCQ <93673602+CalMacCQ@users.noreply.github.com>
Date: Mon, 27 Oct 2025 11:40:53 +0000
Subject: [PATCH 05/34] fix import

---
 hugr-py/src/hugr/hugr/pass.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/hugr-py/src/hugr/hugr/pass.py b/hugr-py/src/hugr/hugr/pass.py
index c26cd01344..ac9c594c74 100644
--- a/hugr-py/src/hugr/hugr/pass.py
+++ b/hugr-py/src/hugr/hugr/pass.py
@@ -5,7 +5,7 @@
 from typing_extensions import Self
 
 from hugr.hugr.base import Hugr
-from hugr.node_port import Node
+from hugr.hugr.node_port import Node
 from hugr.ops import Op
 
 

From c52de850fcc60c9a64b295d91a4b53f501654a44 Mon Sep 17 00:00:00 2001
From: CalMacCQ <93673602+CalMacCQ@users.noreply.github.com>
Date: Mon, 27 Oct 2025 13:17:14 +0000
Subject: [PATCH 06/34] remove to_dict and from_dict methods as well as
 supported Ops

---
 hugr-py/src/hugr/hugr/pass.py | 8 --------
 1 file changed, 8 deletions(-)

diff --git a/hugr-py/src/hugr/hugr/pass.py b/hugr-py/src/hugr/hugr/pass.py
index ac9c594c74..ca7907d514 100644
--- a/hugr-py/src/hugr/hugr/pass.py
+++ b/hugr-py/src/hugr/hugr/pass.py
@@ -18,14 +18,6 @@ def then(self, other: Self) -> Self: ...
 
     def with_entrypoint(self, node: Node) -> Self: ...
 
-    @classmethod
-    def from_dict(cls, dictionary: dict) -> Self: ...
-
-    def to_dict(self) -> dict: ...
-
-    @property
-    def supported_ops(self) -> set[Op]: ...
-
     @property
     def is_global(self) -> bool: ...
 

From 6d7afc2b8f88daea25d3d43cffb41616f53a3b54 Mon Sep 17 00:00:00 2001
From: CalMacCQ <93673602+CalMacCQ@users.noreply.github.com>
Date: Mon, 27 Oct 2025 13:17:48 +0000
Subject: [PATCH 07/34] remove unused import

---
 hugr-py/src/hugr/hugr/pass.py | 1 -
 1 file changed, 1 deletion(-)

diff --git a/hugr-py/src/hugr/hugr/pass.py b/hugr-py/src/hugr/hugr/pass.py
index ca7907d514..a6afd50aae 100644
--- a/hugr-py/src/hugr/hugr/pass.py
+++ b/hugr-py/src/hugr/hugr/pass.py
@@ -6,7 +6,6 @@
 
 from hugr.hugr.base import Hugr
 from hugr.hugr.node_port import Node
-from hugr.ops import Op
 
 
 class ComposablePass(Protocol):

From 89fabf038bfe97c6c16d4208f2a42266fb47aa48 Mon Sep 17 00:00:00 2001
From: CalMacCQ <93673602+CalMacCQ@users.noreply.github.com>
Date: Mon, 27 Oct 2025 13:26:09 +0000
Subject: [PATCH 08/34] node -> entrypoint

---
 hugr-py/src/hugr/hugr/pass.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/hugr-py/src/hugr/hugr/pass.py b/hugr-py/src/hugr/hugr/pass.py
index a6afd50aae..0ad945996b 100644
--- a/hugr-py/src/hugr/hugr/pass.py
+++ b/hugr-py/src/hugr/hugr/pass.py
@@ -15,7 +15,7 @@ def __call__(self, hugr: Hugr) -> None: ...
 
     def then(self, other: Self) -> Self: ...
 
-    def with_entrypoint(self, node: Node) -> Self: ...
+    def with_entrypoint(self, entrypoint: Node) -> Self: ...
 
     @property
     def is_global(self) -> bool: ...

From 4878d5f72059541f7f75720f28c2201a0ccd0118 Mon Sep 17 00:00:00 2001
From: CalMacCQ <93673602+CalMacCQ@users.noreply.github.com>
Date: Mon, 27 Oct 2025 13:52:08 +0000
Subject: [PATCH 09/34] rename and update __init__.py

---
 hugr-py/src/hugr/hugr/__init__.py                     | 10 ++++++----
 hugr-py/src/hugr/hugr/{pass.py => composable_pass.py} |  0
 2 files changed, 6 insertions(+), 4 deletions(-)
 rename hugr-py/src/hugr/hugr/{pass.py => composable_pass.py} (100%)

diff --git a/hugr-py/src/hugr/hugr/__init__.py b/hugr-py/src/hugr/hugr/__init__.py
index 3cbc426d7c..ce4113aead 100644
--- a/hugr-py/src/hugr/hugr/__init__.py
+++ b/hugr-py/src/hugr/hugr/__init__.py
@@ -1,6 +1,7 @@
 """The main HUGR structure."""
 
 from .base import Hugr, NodeData
+from .composable_pass import ComposablePass
 from .node_port import (
     Direction,
     InPort,
@@ -10,11 +11,12 @@
 )
 
 __all__ = [
-    "Hugr",
-    "NodeData",
+    "ComposablePass",
     "Direction",
+    "Hugr",
     "InPort",
-    "Wire",
-    "OutPort",
     "Node",
+    "NodeData",
+    "OutPort",
+    "Wire",
 ]
diff --git a/hugr-py/src/hugr/hugr/pass.py b/hugr-py/src/hugr/hugr/composable_pass.py
similarity index 100%
rename from hugr-py/src/hugr/hugr/pass.py
rename to hugr-py/src/hugr/hugr/composable_pass.py

From 954730f1b3984dd497fcab4db3591d164db5714c Mon Sep 17 00:00:00 2001
From: CalMacCQ <93673602+CalMacCQ@users.noreply.github.com>
Date: Tue, 28 Oct 2025 10:26:16 +0000
Subject: [PATCH 10/34] make a passes module

---
 hugr-py/src/hugr/build/__init__.py               | 16 +++++++++-------
 .../{hugr => build/passes}/composable_pass.py    |  0
 hugr-py/src/hugr/hugr/__init__.py                |  2 --
 3 files changed, 9 insertions(+), 9 deletions(-)
 rename hugr-py/src/hugr/{hugr => build/passes}/composable_pass.py (100%)

diff --git a/hugr-py/src/hugr/build/__init__.py b/hugr-py/src/hugr/build/__init__.py
index def20437fc..3111294989 100644
--- a/hugr-py/src/hugr/build/__init__.py
+++ b/hugr-py/src/hugr/build/__init__.py
@@ -5,20 +5,22 @@
 from .cond_loop import Case, Conditional, If, TailLoop
 from .dfg import DefinitionBuilder, DfBase, Dfg, Function
 from .function import Module
+from .passes.composable_pass import ComposablePass
 from .tracked_dfg import TrackedDfg
 
 __all__ = [
-    "ParentBuilder",
-    "Cfg",
     "Block",
     "Case",
-    "If",
+    "Cfg",
+    "ComposablePass",
     "Conditional",
-    "TailLoop",
+    "DefinitionBuilder",
+    "DfBase",
+    "Dfg",
     "Function",
+    "If",
     "Module",
+    "ParentBuilder",
+    "TailLoop",
     "TrackedDfg",
-    "Dfg",
-    "DefinitionBuilder",
-    "DfBase",
 ]
diff --git a/hugr-py/src/hugr/hugr/composable_pass.py b/hugr-py/src/hugr/build/passes/composable_pass.py
similarity index 100%
rename from hugr-py/src/hugr/hugr/composable_pass.py
rename to hugr-py/src/hugr/build/passes/composable_pass.py
diff --git a/hugr-py/src/hugr/hugr/__init__.py b/hugr-py/src/hugr/hugr/__init__.py
index ce4113aead..940f467333 100644
--- a/hugr-py/src/hugr/hugr/__init__.py
+++ b/hugr-py/src/hugr/hugr/__init__.py
@@ -1,7 +1,6 @@
 """The main HUGR structure."""
 
 from .base import Hugr, NodeData
-from .composable_pass import ComposablePass
 from .node_port import (
     Direction,
     InPort,
@@ -11,7 +10,6 @@
 )
 
 __all__ = [
-    "ComposablePass",
     "Direction",
     "Hugr",
     "InPort",

From 448b5cfe97ae0c1f88ea5b5e35e983529a40e56b Mon Sep 17 00:00:00 2001
From: CalMacCQ <93673602+CalMacCQ@users.noreply.github.com>
Date: Tue, 28 Oct 2025 10:30:10 +0000
Subject: [PATCH 11/34] move passes into hugr root

---
 hugr-py/src/hugr/{build => }/passes/composable_pass.py | 0
 1 file changed, 0 insertions(+), 0 deletions(-)
 rename hugr-py/src/hugr/{build => }/passes/composable_pass.py (100%)

diff --git a/hugr-py/src/hugr/build/passes/composable_pass.py b/hugr-py/src/hugr/passes/composable_pass.py
similarity index 100%
rename from hugr-py/src/hugr/build/passes/composable_pass.py
rename to hugr-py/src/hugr/passes/composable_pass.py

From 17d1dc8b45d656258706f6dda373edcd9cee2556 Mon Sep 17 00:00:00 2001
From: CalMacCQ <93673602+CalMacCQ@users.noreply.github.com>
Date: Tue, 28 Oct 2025 10:30:41 +0000
Subject: [PATCH 12/34] remove from build

---
 hugr-py/src/hugr/build/__init__.py | 2 --
 1 file changed, 2 deletions(-)

diff --git a/hugr-py/src/hugr/build/__init__.py b/hugr-py/src/hugr/build/__init__.py
index 3111294989..8720e94f94 100644
--- a/hugr-py/src/hugr/build/__init__.py
+++ b/hugr-py/src/hugr/build/__init__.py
@@ -5,14 +5,12 @@
 from .cond_loop import Case, Conditional, If, TailLoop
 from .dfg import DefinitionBuilder, DfBase, Dfg, Function
 from .function import Module
-from .passes.composable_pass import ComposablePass
 from .tracked_dfg import TrackedDfg
 
 __all__ = [
     "Block",
     "Case",
     "Cfg",
-    "ComposablePass",
     "Conditional",
     "DefinitionBuilder",
     "DfBase",

From b6fa9a58eacc8bc1c81617dcb9a7bde51cfeaf1e Mon Sep 17 00:00:00 2001
From: CalMacCQ <93673602+CalMacCQ@users.noreply.github.com>
Date: Tue, 28 Oct 2025 10:32:31 +0000
Subject: [PATCH 13/34] add __init__.py for passes

---
 hugr-py/src/hugr/passes/__init__.py | 1 +
 1 file changed, 1 insertion(+)
 create mode 100644 hugr-py/src/hugr/passes/__init__.py

diff --git a/hugr-py/src/hugr/passes/__init__.py b/hugr-py/src/hugr/passes/__init__.py
new file mode 100644
index 0000000000..8a34628c1d
--- /dev/null
+++ b/hugr-py/src/hugr/passes/__init__.py
@@ -0,0 +1 @@
+"""A hugr-py passes module for hugr transformations."""

From cc9c1518983f0d2022563c08534d88b826445f8f Mon Sep 17 00:00:00 2001
From: CalMacCQ <93673602+CalMacCQ@users.noreply.github.com>
Date: Tue, 28 Oct 2025 10:34:35 +0000
Subject: [PATCH 14/34] undo init changes

---
 hugr-py/src/hugr/build/__init__.py | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/hugr-py/src/hugr/build/__init__.py b/hugr-py/src/hugr/build/__init__.py
index 8720e94f94..def20437fc 100644
--- a/hugr-py/src/hugr/build/__init__.py
+++ b/hugr-py/src/hugr/build/__init__.py
@@ -8,17 +8,17 @@
 from .tracked_dfg import TrackedDfg
 
 __all__ = [
+    "ParentBuilder",
+    "Cfg",
     "Block",
     "Case",
-    "Cfg",
+    "If",
     "Conditional",
-    "DefinitionBuilder",
-    "DfBase",
-    "Dfg",
+    "TailLoop",
     "Function",
-    "If",
     "Module",
-    "ParentBuilder",
-    "TailLoop",
     "TrackedDfg",
+    "Dfg",
+    "DefinitionBuilder",
+    "DfBase",
 ]

From 2d10e874381a2c767f65affa92c8e5b35d6d3f26 Mon Sep 17 00:00:00 2001
From: CalMacCQ <93673602+CalMacCQ@users.noreply.github.com>
Date: Tue, 28 Oct 2025 10:35:28 +0000
Subject: [PATCH 15/34] update __all__

---
 hugr-py/src/hugr/hugr/__init__.py | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/hugr-py/src/hugr/hugr/__init__.py b/hugr-py/src/hugr/hugr/__init__.py
index 940f467333..3e2011e610 100644
--- a/hugr-py/src/hugr/hugr/__init__.py
+++ b/hugr-py/src/hugr/hugr/__init__.py
@@ -10,9 +10,13 @@
 )
 
 __all__ = [
+    "Hugr",
+    "NodeData",
     "Direction",
     "Hugr",
     "InPort",
+    "Wire",
+    "OutPort",
     "Node",
     "NodeData",
     "OutPort",

From 45bd86aefe91d7426fb34026b08faa6b29d384db Mon Sep 17 00:00:00 2001
From: CalMacCQ <93673602+CalMacCQ@users.noreply.github.com>
Date: Tue, 28 Oct 2025 10:36:28 +0000
Subject: [PATCH 16/34] fix __all__ again

---
 hugr-py/src/hugr/hugr/__init__.py | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/hugr-py/src/hugr/hugr/__init__.py b/hugr-py/src/hugr/hugr/__init__.py
index 3e2011e610..3cbc426d7c 100644
--- a/hugr-py/src/hugr/hugr/__init__.py
+++ b/hugr-py/src/hugr/hugr/__init__.py
@@ -13,12 +13,8 @@
     "Hugr",
     "NodeData",
     "Direction",
-    "Hugr",
     "InPort",
     "Wire",
     "OutPort",
     "Node",
-    "NodeData",
-    "OutPort",
-    "Wire",
 ]

From 6ca653e189f42db40698344d0207ad03538bee21 Mon Sep 17 00:00:00 2001
From: Callum Macpherson <callum.macpherson@quantinuum.com>
Date: Wed, 12 Nov 2025 11:54:13 +0000
Subject: [PATCH 17/34] minimal methods for ComposablePass

---
 hugr-py/src/hugr/passes/composable_pass.py | 9 ---------
 1 file changed, 9 deletions(-)

diff --git a/hugr-py/src/hugr/passes/composable_pass.py b/hugr-py/src/hugr/passes/composable_pass.py
index 0ad945996b..c7b3844fdd 100644
--- a/hugr-py/src/hugr/passes/composable_pass.py
+++ b/hugr-py/src/hugr/passes/composable_pass.py
@@ -5,7 +5,6 @@
 from typing_extensions import Self
 
 from hugr.hugr.base import Hugr
-from hugr.hugr.node_port import Node
 
 
 class ComposablePass(Protocol):
@@ -14,11 +13,3 @@ class ComposablePass(Protocol):
     def __call__(self, hugr: Hugr) -> None: ...
 
     def then(self, other: Self) -> Self: ...
-
-    def with_entrypoint(self, entrypoint: Node) -> Self: ...
-
-    @property
-    def is_global(self) -> bool: ...
-
-    @property
-    def is_recursive(self) -> bool: ...

From 9171dba76d10d2245493921ebcf9b4420ccbf58b Mon Sep 17 00:00:00 2001
From: Callum Macpherson <callum.macpherson@quantinuum.com>
Date: Wed, 12 Nov 2025 11:59:12 +0000
Subject: [PATCH 18/34] add ComposedPass dataclass

---
 hugr-py/src/hugr/passes/composable_pass.py | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/hugr-py/src/hugr/passes/composable_pass.py b/hugr-py/src/hugr/passes/composable_pass.py
index c7b3844fdd..43a9c5fe95 100644
--- a/hugr-py/src/hugr/passes/composable_pass.py
+++ b/hugr-py/src/hugr/passes/composable_pass.py
@@ -1,6 +1,7 @@
 """A Protocol for a composable pass."""
 
 from typing import Protocol
+from dataclasses import dataclass
 
 from typing_extensions import Self
 
@@ -13,3 +14,14 @@ class ComposablePass(Protocol):
     def __call__(self, hugr: Hugr) -> None: ...
 
     def then(self, other: Self) -> Self: ...
+
+
+@dataclass
+class ComposedPass(ComposablePass):
+   """A Sequence of composable passes."""
+   passes: list[ComposablePass]
+
+   def __call__(self, hugr: Hugr):
+       for comp_pass in self.passes:
+           self.comp_pass(hugr)
+       

From c6fbfc0920eeb008947b0afd0db7d902f53a77ef Mon Sep 17 00:00:00 2001
From: Callum Macpherson <callum.macpherson@quantinuum.com>
Date: Wed, 12 Nov 2025 12:08:33 +0000
Subject: [PATCH 19/34] fix to comp_pass

---
 hugr-py/src/hugr/passes/composable_pass.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/hugr-py/src/hugr/passes/composable_pass.py b/hugr-py/src/hugr/passes/composable_pass.py
index 43a9c5fe95..39746eb6f7 100644
--- a/hugr-py/src/hugr/passes/composable_pass.py
+++ b/hugr-py/src/hugr/passes/composable_pass.py
@@ -23,5 +23,5 @@ class ComposedPass(ComposablePass):
 
    def __call__(self, hugr: Hugr):
        for comp_pass in self.passes:
-           self.comp_pass(hugr)
+           comp_pass(hugr)
        

From fcf00c0c44871a364c39c1f0dcdfda33406f9be2 Mon Sep 17 00:00:00 2001
From: Callum Macpherson <callum.macpherson@quantinuum.com>
Date: Wed, 12 Nov 2025 12:21:33 +0000
Subject: [PATCH 20/34] docstrings

---
 hugr-py/src/hugr/passes/composable_pass.py | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/hugr-py/src/hugr/passes/composable_pass.py b/hugr-py/src/hugr/passes/composable_pass.py
index 39746eb6f7..31d6ab50d3 100644
--- a/hugr-py/src/hugr/passes/composable_pass.py
+++ b/hugr-py/src/hugr/passes/composable_pass.py
@@ -11,17 +11,22 @@
 class ComposablePass(Protocol):
     """A Protocol which represents a composable Hugr transformation."""
 
-    def __call__(self, hugr: Hugr) -> None: ...
+    def __call__(self, hugr: Hugr) -> None:
+        """Call the pass to transform a HUGR."""
+        ...
 
-    def then(self, other: Self) -> Self: ...
+    def then(self, other: Self) -> Self:
+       """Perform another composable pass after this pass."""
+       ...
 
 
 @dataclass
 class ComposedPass(ComposablePass):
-   """A Sequence of composable passes."""
+   """A sequence of composable passes."""
    passes: list[ComposablePass]
 
    def __call__(self, hugr: Hugr):
+       """Call all of the passes in sequence."""
        for comp_pass in self.passes:
            comp_pass(hugr)
        

From 3ae525c198c7f84505aa368155ec41be5a6e258c Mon Sep 17 00:00:00 2001
From: Callum Macpherson <callum.macpherson@quantinuum.com>
Date: Wed, 12 Nov 2025 12:23:24 +0000
Subject: [PATCH 21/34] formatting stuff

---
 hugr-py/src/hugr/passes/composable_pass.py | 20 ++++++++++----------
 1 file changed, 10 insertions(+), 10 deletions(-)

diff --git a/hugr-py/src/hugr/passes/composable_pass.py b/hugr-py/src/hugr/passes/composable_pass.py
index 31d6ab50d3..e53d9db9c1 100644
--- a/hugr-py/src/hugr/passes/composable_pass.py
+++ b/hugr-py/src/hugr/passes/composable_pass.py
@@ -16,17 +16,17 @@ def __call__(self, hugr: Hugr) -> None:
         ...
 
     def then(self, other: Self) -> Self:
-       """Perform another composable pass after this pass."""
-       ...
+        """Perform another composable pass after this pass."""
+        ...
 
 
 @dataclass
 class ComposedPass(ComposablePass):
-   """A sequence of composable passes."""
-   passes: list[ComposablePass]
-
-   def __call__(self, hugr: Hugr):
-       """Call all of the passes in sequence."""
-       for comp_pass in self.passes:
-           comp_pass(hugr)
-       
+    """A sequence of composable passes."""
+
+    passes: list[ComposablePass]
+
+    def __call__(self, hugr: Hugr):
+        """Call all of the passes in sequence."""
+        for comp_pass in self.passes:
+            comp_pass(hugr)

From af225a334e128e93fb9c99ffa634be3bbc4fb3b7 Mon Sep 17 00:00:00 2001
From: Callum Macpherson <callum.macpherson@quantinuum.com>
Date: Wed, 12 Nov 2025 13:41:37 +0000
Subject: [PATCH 22/34] more ruff check

---
 hugr-py/src/hugr/passes/composable_pass.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/hugr-py/src/hugr/passes/composable_pass.py b/hugr-py/src/hugr/passes/composable_pass.py
index e53d9db9c1..65dc06875a 100644
--- a/hugr-py/src/hugr/passes/composable_pass.py
+++ b/hugr-py/src/hugr/passes/composable_pass.py
@@ -1,7 +1,7 @@
 """A Protocol for a composable pass."""
 
-from typing import Protocol
 from dataclasses import dataclass
+from typing import Protocol
 
 from typing_extensions import Self
 

From 92964a8d9d3d6d0436e0fdff5efbe2520d5838b4 Mon Sep 17 00:00:00 2001
From: Callum Macpherson <callum.macpherson@quantinuum.com>
Date: Wed, 12 Nov 2025 15:13:23 +0000
Subject: [PATCH 23/34] provide a default implementation of then() method

---
 hugr-py/src/hugr/passes/composable_pass.py | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/hugr-py/src/hugr/passes/composable_pass.py b/hugr-py/src/hugr/passes/composable_pass.py
index 65dc06875a..b7ece2fe95 100644
--- a/hugr-py/src/hugr/passes/composable_pass.py
+++ b/hugr-py/src/hugr/passes/composable_pass.py
@@ -17,7 +17,15 @@ def __call__(self, hugr: Hugr) -> None:
 
     def then(self, other: Self) -> Self:
         """Perform another composable pass after this pass."""
-        ...
+        pass_list = [] 
+        if isinstance(self, ComposedPass) or isinstance(other, ComposedPass):
+            if isinstance(self, ComposedPass):
+                pass_list.append(self.passes)
+            elif isinstance(other, ComposedPass):
+                pass_list.append(other.passes)
+        else:
+            return ComposedPass([self, other])
+
 
 
 @dataclass

From f139d7c67bb81d48baebe1cc1fe51103921c1f69 Mon Sep 17 00:00:00 2001
From: Callum Macpherson <callum.macpherson@quantinuum.com>
Date: Wed, 12 Nov 2025 15:19:58 +0000
Subject: [PATCH 24/34] fix default impl

---
 hugr-py/src/hugr/passes/composable_pass.py | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/hugr-py/src/hugr/passes/composable_pass.py b/hugr-py/src/hugr/passes/composable_pass.py
index b7ece2fe95..c8d6bdd925 100644
--- a/hugr-py/src/hugr/passes/composable_pass.py
+++ b/hugr-py/src/hugr/passes/composable_pass.py
@@ -17,12 +17,12 @@ def __call__(self, hugr: Hugr) -> None:
 
     def then(self, other: Self) -> Self:
         """Perform another composable pass after this pass."""
-        pass_list = [] 
+        # Provide a default implementation for composing passes.
         if isinstance(self, ComposedPass) or isinstance(other, ComposedPass):
-            if isinstance(self, ComposedPass):
-                pass_list.append(self.passes)
-            elif isinstance(other, ComposedPass):
-                pass_list.append(other.passes)
+            if isinstance(self, ComposedPass) and not isinstance(other, ComposedPass):
+                return ComposedPass([self.passes, other])
+            elif isinstance(other, ComposedPass) and not isinstance(self, ComposedPass):
+                return ComposedPass([self, other.passes])
         else:
             return ComposedPass([self, other])
 

From df0ab1577bcfe84e16125e8f0c6719a7da0538e5 Mon Sep 17 00:00:00 2001
From: Callum Macpherson <callum.macpherson@quantinuum.com>
Date: Wed, 12 Nov 2025 15:40:45 +0000
Subject: [PATCH 25/34] fixup then impl

---
 hugr-py/src/hugr/passes/composable_pass.py | 19 ++++++++++++-------
 1 file changed, 12 insertions(+), 7 deletions(-)

diff --git a/hugr-py/src/hugr/passes/composable_pass.py b/hugr-py/src/hugr/passes/composable_pass.py
index c8d6bdd925..6fbefa72b0 100644
--- a/hugr-py/src/hugr/passes/composable_pass.py
+++ b/hugr-py/src/hugr/passes/composable_pass.py
@@ -15,16 +15,21 @@ def __call__(self, hugr: Hugr) -> None:
         """Call the pass to transform a HUGR."""
         ...
 
-    def then(self, other: Self) -> Self:
+    def then(self, other: Self) -> ComposedPass:
         """Perform another composable pass after this pass."""
         # Provide a default implementation for composing passes.
-        if isinstance(self, ComposedPass) or isinstance(other, ComposedPass):
-            if isinstance(self, ComposedPass) and not isinstance(other, ComposedPass):
-                return ComposedPass([self.passes, other])
-            elif isinstance(other, ComposedPass) and not isinstance(self, ComposedPass):
-                return ComposedPass([self, other.passes])
+        pass_list = []
+        if isinstance(self, ComposedPass):
+            pass_list.extend(self.passes)
         else:
-            return ComposedPass([self, other])
+            pass_list.append(self)
+        
+        if isinstance(other, ComposedPass):
+            pass_list.extend(other.passes)
+        else:
+            pass_list.append(other)
+        
+        return ComposedPass(pass_list)
 
 
 

From ac63dd54a0c5986db731fc32a6e40243944c19c4 Mon Sep 17 00:00:00 2001
From: Callum Macpherson <callum.macpherson@quantinuum.com>
Date: Wed, 12 Nov 2025 15:50:36 +0000
Subject: [PATCH 26/34] fixup mypy and ruff

---
 hugr-py/src/hugr/passes/composable_pass.py | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/hugr-py/src/hugr/passes/composable_pass.py b/hugr-py/src/hugr/passes/composable_pass.py
index 6fbefa72b0..9d5b100d9c 100644
--- a/hugr-py/src/hugr/passes/composable_pass.py
+++ b/hugr-py/src/hugr/passes/composable_pass.py
@@ -1,4 +1,5 @@
 """A Protocol for a composable pass."""
+from __future__ import annotations
 
 from dataclasses import dataclass
 from typing import Protocol
@@ -15,7 +16,7 @@ def __call__(self, hugr: Hugr) -> None:
         """Call the pass to transform a HUGR."""
         ...
 
-    def then(self, other: Self) -> ComposedPass:
+    def then(self, other: Self) -> ComposablePass:
         """Perform another composable pass after this pass."""
         # Provide a default implementation for composing passes.
         pass_list = []
@@ -23,14 +24,13 @@ def then(self, other: Self) -> ComposedPass:
             pass_list.extend(self.passes)
         else:
             pass_list.append(self)
-        
+
         if isinstance(other, ComposedPass):
             pass_list.extend(other.passes)
         else:
             pass_list.append(other)
-        
-        return ComposedPass(pass_list)
 
+        return ComposedPass([self, other])
 
 
 @dataclass

From 9a157b8d08b607f6ed922dc12c15a3c72306b76f Mon Sep 17 00:00:00 2001
From: Callum Macpherson <callum.macpherson@quantinuum.com>
Date: Wed, 12 Nov 2025 15:51:15 +0000
Subject: [PATCH 27/34] yet another fix

---
 hugr-py/src/hugr/passes/composable_pass.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/hugr-py/src/hugr/passes/composable_pass.py b/hugr-py/src/hugr/passes/composable_pass.py
index 9d5b100d9c..3ef85e8ce0 100644
--- a/hugr-py/src/hugr/passes/composable_pass.py
+++ b/hugr-py/src/hugr/passes/composable_pass.py
@@ -30,7 +30,7 @@ def then(self, other: Self) -> ComposablePass:
         else:
             pass_list.append(other)
 
-        return ComposedPass([self, other])
+        return ComposedPass(pass_list)
 
 
 @dataclass

From 3db5bdd8773bf9afea2478d8787ef7c31148cd51 Mon Sep 17 00:00:00 2001
From: Callum Macpherson <callum.macpherson@quantinuum.com>
Date: Wed, 12 Nov 2025 15:52:17 +0000
Subject: [PATCH 28/34] more ruff nonsense

---
 hugr-py/src/hugr/passes/composable_pass.py | 1 +
 1 file changed, 1 insertion(+)

diff --git a/hugr-py/src/hugr/passes/composable_pass.py b/hugr-py/src/hugr/passes/composable_pass.py
index 3ef85e8ce0..9f79ce4f16 100644
--- a/hugr-py/src/hugr/passes/composable_pass.py
+++ b/hugr-py/src/hugr/passes/composable_pass.py
@@ -1,4 +1,5 @@
 """A Protocol for a composable pass."""
+
 from __future__ import annotations
 
 from dataclasses import dataclass

From 67d7d3858cc07964b494e6509e1aa3e2d6d504cc Mon Sep 17 00:00:00 2001
From: Callum Macpherson <callum.macpherson@quantinuum.com>
Date: Wed, 12 Nov 2025 15:53:08 +0000
Subject: [PATCH 29/34] rm self

---
 hugr-py/src/hugr/passes/composable_pass.py | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/hugr-py/src/hugr/passes/composable_pass.py b/hugr-py/src/hugr/passes/composable_pass.py
index 9f79ce4f16..4cde6fcc18 100644
--- a/hugr-py/src/hugr/passes/composable_pass.py
+++ b/hugr-py/src/hugr/passes/composable_pass.py
@@ -5,8 +5,6 @@
 from dataclasses import dataclass
 from typing import Protocol
 
-from typing_extensions import Self
-
 from hugr.hugr.base import Hugr
 
 
@@ -17,7 +15,7 @@ def __call__(self, hugr: Hugr) -> None:
         """Call the pass to transform a HUGR."""
         ...
 
-    def then(self, other: Self) -> ComposablePass:
+    def then(self, other: ComposablePass) -> ComposablePass:
         """Perform another composable pass after this pass."""
         # Provide a default implementation for composing passes.
         pass_list = []

From 975ddbb03806c0198e3db9fc9b86e723d0656e18 Mon Sep 17 00:00:00 2001
From: Callum Macpherson <callum.macpherson@quantinuum.com>
Date: Wed, 12 Nov 2025 15:56:22 +0000
Subject: [PATCH 30/34] fixes

---
 hugr-py/src/hugr/passes/composable_pass.py | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/hugr-py/src/hugr/passes/composable_pass.py b/hugr-py/src/hugr/passes/composable_pass.py
index 4cde6fcc18..09981587a3 100644
--- a/hugr-py/src/hugr/passes/composable_pass.py
+++ b/hugr-py/src/hugr/passes/composable_pass.py
@@ -3,9 +3,10 @@
 from __future__ import annotations
 
 from dataclasses import dataclass
-from typing import Protocol
+from typing import TYPE_CHECKING, Protocol
 
-from hugr.hugr.base import Hugr
+if TYPE_CHECKING:
+    from hugr.hugr.base import Hugr
 
 
 class ComposablePass(Protocol):

From 0165ae777c4d669c882cf1ee3bbd00d46af58061 Mon Sep 17 00:00:00 2001
From: Callum Macpherson <93673602+CalMacCQ@users.noreply.github.com>
Date: Wed, 12 Nov 2025 16:35:17 +0000
Subject: [PATCH 31/34] Update hugr-py/src/hugr/passes/composable_pass.py
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Co-authored-by: Agustín Borgna <121866228+aborgna-q@users.noreply.github.com>
---
 hugr-py/src/hugr/passes/composable_pass.py | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/hugr-py/src/hugr/passes/composable_pass.py b/hugr-py/src/hugr/passes/composable_pass.py
index 09981587a3..485c67a064 100644
--- a/hugr-py/src/hugr/passes/composable_pass.py
+++ b/hugr-py/src/hugr/passes/composable_pass.py
@@ -31,7 +31,9 @@ def then(self, other: ComposablePass) -> ComposablePass:
             pass_list.append(other)
 
         return ComposedPass(pass_list)
-
+    def name(self) -> str:
+        """Returns the name of the Pass"""
+        return self.__class__.__name__
 
 @dataclass
 class ComposedPass(ComposablePass):

From 2def5fc001e8eeb782f8c752cb5b263375ad4f32 Mon Sep 17 00:00:00 2001
From: Callum Macpherson <callum.macpherson@quantinuum.com>
Date: Wed, 12 Nov 2025 16:36:43 +0000
Subject: [PATCH 32/34] fmt

---
 hugr-py/src/hugr/passes/composable_pass.py | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/hugr-py/src/hugr/passes/composable_pass.py b/hugr-py/src/hugr/passes/composable_pass.py
index 485c67a064..c81dd62197 100644
--- a/hugr-py/src/hugr/passes/composable_pass.py
+++ b/hugr-py/src/hugr/passes/composable_pass.py
@@ -16,6 +16,10 @@ def __call__(self, hugr: Hugr) -> None:
         """Call the pass to transform a HUGR."""
         ...
 
+    def name(self) -> str:
+        """Returns the name of the pass."""
+        return self.__class__.__name__
+
     def then(self, other: ComposablePass) -> ComposablePass:
         """Perform another composable pass after this pass."""
         # Provide a default implementation for composing passes.
@@ -31,9 +35,7 @@ def then(self, other: ComposablePass) -> ComposablePass:
             pass_list.append(other)
 
         return ComposedPass(pass_list)
-    def name(self) -> str:
-        """Returns the name of the Pass"""
-        return self.__class__.__name__
+
 
 @dataclass
 class ComposedPass(ComposablePass):

From 9673dc29b35ac3a81fdf81c6214e6e310e247926 Mon Sep 17 00:00:00 2001
From: Callum Macpherson <callum.macpherson@quantinuum.com>
Date: Wed, 12 Nov 2025 17:01:15 +0000
Subject: [PATCH 33/34] make name a property

---
 hugr-py/src/hugr/passes/composable_pass.py | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/hugr-py/src/hugr/passes/composable_pass.py b/hugr-py/src/hugr/passes/composable_pass.py
index c81dd62197..90f41fb0e5 100644
--- a/hugr-py/src/hugr/passes/composable_pass.py
+++ b/hugr-py/src/hugr/passes/composable_pass.py
@@ -3,12 +3,13 @@
 from __future__ import annotations
 
 from dataclasses import dataclass
-from typing import TYPE_CHECKING, Protocol
+from typing import TYPE_CHECKING, Protocol, runtime_checkable
 
 if TYPE_CHECKING:
     from hugr.hugr.base import Hugr
 
 
+@runtime_checkable
 class ComposablePass(Protocol):
     """A Protocol which represents a composable Hugr transformation."""
 
@@ -16,6 +17,7 @@ def __call__(self, hugr: Hugr) -> None:
         """Call the pass to transform a HUGR."""
         ...
 
+    @property
     def name(self) -> str:
         """Returns the name of the pass."""
         return self.__class__.__name__

From 01b71269baf9a60c61dd28f7a367f02b29a767cf Mon Sep 17 00:00:00 2001
From: Callum Macpherson <callum.macpherson@quantinuum.com>
Date: Wed, 12 Nov 2025 17:01:32 +0000
Subject: [PATCH 34/34] add a dummy test

---
 hugr-py/tests/test_passes.py | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)
 create mode 100644 hugr-py/tests/test_passes.py

diff --git a/hugr-py/tests/test_passes.py b/hugr-py/tests/test_passes.py
new file mode 100644
index 0000000000..542ef1f8b5
--- /dev/null
+++ b/hugr-py/tests/test_passes.py
@@ -0,0 +1,26 @@
+from hugr.hugr.base import Hugr
+from hugr.passes.composable_pass import ComposablePass, ComposedPass
+
+
+def test_composable_pass() -> None:
+    class MyDummyPass(ComposablePass):
+        def __call__(self, hugr: Hugr) -> None:
+            return self(hugr)
+
+        def then(self, other: ComposablePass) -> ComposablePass:
+            return ComposedPass([self, other])
+
+        @property
+        def name(self) -> str:
+            return "Dummy"
+
+    dummy = MyDummyPass()
+
+    composed = dummy.then(dummy)
+
+    my_composed_pass = ComposedPass([dummy, dummy])
+
+    assert my_composed_pass.passes == [dummy, dummy]
+    assert isinstance(my_composed_pass, ComposablePass)
+    assert isinstance(composed, ComposablePass)
+    assert dummy.name == "Dummy"