From b3f3eab09e887f8dbc8dee19d2c5983e66cb7d12 Mon Sep 17 00:00:00 2001
From: BobTheBuidler <bobthebuidlerdefi@gmail.com>
Date: Tue, 12 Aug 2025 02:15:57 +0000
Subject: [PATCH 01/29] [mypyc] feat: ForFilter generator helper for
 builtins.filter

---
 mypyc/irbuild/for_helpers.py       | 52 ++++++++++++++++++++++
 mypyc/test-data/irbuild-basic.test | 70 ++++++++++++++++++++++++++++++
 mypyc/test-data/run-loops.test     | 30 +++++++++++++
 3 files changed, 152 insertions(+)

diff --git a/mypyc/irbuild/for_helpers.py b/mypyc/irbuild/for_helpers.py
index 5cf89f579ec4..99f51339f912 100644
--- a/mypyc/irbuild/for_helpers.py
+++ b/mypyc/irbuild/for_helpers.py
@@ -490,6 +490,16 @@ def make_for_loop_generator(
             for_list = ForSequence(builder, index, body_block, loop_exit, line, nested)
             for_list.init(expr_reg, target_type, reverse=True)
             return for_list
+        
+        elif (
+            expr.callee.fullname == "builtins.filter"
+            and len(expr.args) == 2
+            and all(k == ARG_POS for k in expr.arg_kinds)
+        ):
+            for_filter = ForFilter(builder, index, body_block, loop_exit, line, nested)
+            for_filter.init(index, expr.args[0], expr.args[1])
+            return for_filter
+    
     if isinstance(expr, CallExpr) and isinstance(expr.callee, MemberExpr) and not expr.args:
         # Special cases for dictionary iterator methods, like dict.items().
         rtype = builder.node_type(expr.callee.expr)
@@ -1147,3 +1157,45 @@ def gen_step(self) -> None:
     def gen_cleanup(self) -> None:
         for gen in self.gens:
             gen.gen_cleanup()
+
+
+class ForFilter(ForGenerator):
+    """Generate optimized IR for a for loop over filter(f, iterable)."""
+
+    def need_cleanup(self) -> bool:
+        # The wrapped for loops might need cleanup. We might generate a
+        # redundant cleanup block, but that's okay.
+        return True
+
+    def init(self, index: Lvalue, func: Expression, iterable: Expression) -> None:
+        self.filter_func = self.builder.accept(func)
+        self.iterable = iterable
+        self.index = index
+
+        self.gen = make_for_loop_generator(
+            self.builder, self.index, self.iterable, self.body_block, self.loop_exit, self.line, is_async=False, nested=True
+        )
+
+    def gen_condition(self) -> None:
+        builder = self.builder
+        line = self.line
+        # First, get the next item from the sub-generator
+        self.gen.gen_condition()
+        # Now, filter: only enter the body if func(item) is truthy
+        filter_block = BasicBlock()
+        builder.activate_block(filter_block)
+        self.gen.begin_body()
+        item = builder.read(builder.get_assignment_target(self.index), line)
+        # TODO: implement logic to handle c calls of native functions
+        result = builder.py_call(self.filter_func, [item], line)
+        builder.add_bool_branch(result, self.body_block, self.loop_exit)
+
+    def begin_body(self) -> None:
+        # The item is already assigned to self.index by the sub-generator.
+        pass
+
+    def gen_step(self) -> None:
+        self.gen.gen_step()
+
+    def gen_cleanup(self) -> None:
+        self.gen.gen_cleanup()
diff --git a/mypyc/test-data/irbuild-basic.test b/mypyc/test-data/irbuild-basic.test
index 4a7d315ec836..46db61125f5b 100644
--- a/mypyc/test-data/irbuild-basic.test
+++ b/mypyc/test-data/irbuild-basic.test
@@ -3546,3 +3546,73 @@ L0:
     r2 = PyObject_Vectorcall(r1, 0, 0, 0)
     r3 = box(None, 1)
     return r3
+
+[case testForFilter]
+def f(x: int) -> bool:
+    return bool(x % 2)
+def g(a: list[int]) -> int:
+    s = 0
+    for x in filter(f, a):
+        s += x
+    return s
+[out]
+def f(x):
+    x, r0 :: int
+    r1 :: bit
+L0:
+    r0 = CPyTagged_Remainder(x, 4)
+    r1 = r0 != 0
+    return r1
+def g(a):
+    a :: list
+    s :: int
+    r0 :: dict
+    r1 :: str
+    r2 :: object
+    r3, r4 :: native_int
+    r5 :: bit
+    r6 :: object
+    r7, x :: int
+    r8 :: object
+    r9 :: object[1]
+    r10 :: object_ptr
+    r11 :: object
+    r12 :: i32
+    r13 :: bit
+    r14 :: bool
+    r15 :: int
+    r16 :: native_int
+L0:
+    s = 0
+    r0 = __main__.globals :: static
+    r1 = 'f'
+    r2 = CPyDict_GetItem(r0, r1)
+    r3 = 0
+L1:
+    r4 = var_object_size a
+    r5 = r3 < r4 :: signed
+    if r5 goto L3 else goto L5 :: bool
+L2:
+    r6 = list_get_item_unsafe a, r3
+    r7 = unbox(int, r6)
+    x = r7
+    r8 = box(int, x)
+    r9 = [r8]
+    r10 = load_address r9
+    r11 = PyObject_Vectorcall(r2, r10, 1, 0)
+    keep_alive r8
+    r12 = PyObject_IsTrue(r11)
+    r13 = r12 >= 0 :: signed
+    r14 = truncate r12: i32 to builtins.bool
+    if r14 goto L3 else goto L5 :: bool
+L3:
+    r15 = CPyTagged_Add(s, x)
+    s = r15
+L4:
+    r16 = r3 + 1
+    r3 = r16
+    goto L1
+L5:
+L6:
+    return s
+
diff --git a/mypyc/test-data/run-loops.test b/mypyc/test-data/run-loops.test
index 3cbb07297e6e..3f4de2f4c9cc 100644
--- a/mypyc/test-data/run-loops.test
+++ b/mypyc/test-data/run-loops.test
@@ -571,3 +571,33 @@ print([x for x in native.Vector2(4, -5.2)])
 [out]
 Vector2(x=-2, y=3.1)
 \[4, -5.2]
+
+[case testRunForFilter]
+def f(a: list[int]) -> int:
+    s = 0
+    for x in filter(lambda x: x % 2 == 0, a):
+        s += x
+    return s
+
+print(f([1, 2, 3, 4, 5, 6]))
+print(f([1, 3, 5]))
+print(f([]))
+
+[out]
+12
+0
+0
+
+[case testRunForFilterEdgeCases]
+def f(a: list[int]) -> int:
+    s = 0
+    for x in filter(lambda x: x > 10, a):
+        s += x
+    return s
+
+print(f([5, 15, 25]))
+print(f([]))
+
+[out]
+40
+0

From 67818c616d5c8ef15ae93821b821e11e47eba798 Mon Sep 17 00:00:00 2001
From: "pre-commit-ci[bot]"
 <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Date: Tue, 12 Aug 2025 02:18:18 +0000
Subject: [PATCH 02/29] [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci
---
 mypyc/irbuild/for_helpers.py       | 13 ++++++++++---
 mypyc/test-data/irbuild-basic.test |  1 -
 2 files changed, 10 insertions(+), 4 deletions(-)

diff --git a/mypyc/irbuild/for_helpers.py b/mypyc/irbuild/for_helpers.py
index 99f51339f912..1b824e2d1ddd 100644
--- a/mypyc/irbuild/for_helpers.py
+++ b/mypyc/irbuild/for_helpers.py
@@ -490,7 +490,7 @@ def make_for_loop_generator(
             for_list = ForSequence(builder, index, body_block, loop_exit, line, nested)
             for_list.init(expr_reg, target_type, reverse=True)
             return for_list
-        
+
         elif (
             expr.callee.fullname == "builtins.filter"
             and len(expr.args) == 2
@@ -499,7 +499,7 @@ def make_for_loop_generator(
             for_filter = ForFilter(builder, index, body_block, loop_exit, line, nested)
             for_filter.init(index, expr.args[0], expr.args[1])
             return for_filter
-    
+
     if isinstance(expr, CallExpr) and isinstance(expr.callee, MemberExpr) and not expr.args:
         # Special cases for dictionary iterator methods, like dict.items().
         rtype = builder.node_type(expr.callee.expr)
@@ -1173,7 +1173,14 @@ def init(self, index: Lvalue, func: Expression, iterable: Expression) -> None:
         self.index = index
 
         self.gen = make_for_loop_generator(
-            self.builder, self.index, self.iterable, self.body_block, self.loop_exit, self.line, is_async=False, nested=True
+            self.builder,
+            self.index,
+            self.iterable,
+            self.body_block,
+            self.loop_exit,
+            self.line,
+            is_async=False,
+            nested=True,
         )
 
     def gen_condition(self) -> None:
diff --git a/mypyc/test-data/irbuild-basic.test b/mypyc/test-data/irbuild-basic.test
index 46db61125f5b..4fb9869c9bf0 100644
--- a/mypyc/test-data/irbuild-basic.test
+++ b/mypyc/test-data/irbuild-basic.test
@@ -3615,4 +3615,3 @@ L4:
 L5:
 L6:
     return s
-

From 74b7a6ed2e958d349eb1b9e68bf26fcd3f41ecfd Mon Sep 17 00:00:00 2001
From: BobTheBuidler <bobthebuidlerdefi@gmail.com>
Date: Tue, 12 Aug 2025 03:19:42 +0000
Subject: [PATCH 03/29] fix: add filter to ir fixtures

---
 mypyc/test-data/fixtures/ir.py | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/mypyc/test-data/fixtures/ir.py b/mypyc/test-data/fixtures/ir.py
index 76afc1ea58cc..cddd05ff5fe9 100644
--- a/mypyc/test-data/fixtures/ir.py
+++ b/mypyc/test-data/fixtures/ir.py
@@ -7,6 +7,8 @@
     overload, Mapping, Union, Callable, Sequence, FrozenSet, Protocol
 )
 
+from typing_extensions import Self
+
 _T = TypeVar('_T')
 T_co = TypeVar('T_co', covariant=True)
 T_contra = TypeVar('T_contra', contravariant=True)
@@ -405,3 +407,22 @@ class classmethod: pass
 class staticmethod: pass
 
 NotImplemented: Any = ...
+
+_T1 = TypeVar("_T1")
+_T2 = TypeVar("_T2")
+
+class map(Generic[_S]):
+    @overload
+    def __new__(cls, func: Callable[[_T1], _S], iterable: Iterable[_T1], /) -> Self: ...
+    @overload
+    def __new__(cls, func: Callable[[_T1, _T2], _S], iterable: Iterable[_T1], iter2: Iterable[_T2], /) -> Self: ...
+    def __iter__(self) -> Self: ...
+    def __next__(self) -> _S: ...
+    
+class filter(Generic[_T]):
+    @overload
+    def __new__(cls, function: None, iterable: Iterable[_T | None], /) -> Self: ...
+    @overload
+    def __new__(cls, function: Callable[[_T], Any], iterable: Iterable[_T], /) -> Self: ...
+    def __iter__(self) -> Self: ...
+    def __next__(self) -> _T: ...

From eeb09ab88211fc212220b50799671500a56a25ec Mon Sep 17 00:00:00 2001
From: BobTheBuidler <bobthebuidlerdefi@gmail.com>
Date: Tue, 12 Aug 2025 03:19:42 +0000
Subject: [PATCH 04/29] fix: run tests

---
 mypyc/irbuild/for_helpers.py       | 24 ++++++++++++++----------
 mypyc/test-data/irbuild-basic.test | 10 ++++++----
 mypyc/test-data/run-loops.test     |  4 ++++
 3 files changed, 24 insertions(+), 14 deletions(-)

diff --git a/mypyc/irbuild/for_helpers.py b/mypyc/irbuild/for_helpers.py
index 1b824e2d1ddd..c71a7c276510 100644
--- a/mypyc/irbuild/for_helpers.py
+++ b/mypyc/irbuild/for_helpers.py
@@ -1184,22 +1184,26 @@ def init(self, index: Lvalue, func: Expression, iterable: Expression) -> None:
         )
 
     def gen_condition(self) -> None:
-        builder = self.builder
-        line = self.line
-        # First, get the next item from the sub-generator
         self.gen.gen_condition()
-        # Now, filter: only enter the body if func(item) is truthy
-        filter_block = BasicBlock()
-        builder.activate_block(filter_block)
+
+    def begin_body(self) -> None:
+        # 1. Assign the next item to the loop variable
         self.gen.begin_body()
+
+        # 2. Call the filter function
+        builder = self.builder
+        line = self.line
         item = builder.read(builder.get_assignment_target(self.index), line)
         # TODO: implement logic to handle c calls of native functions
         result = builder.py_call(self.filter_func, [item], line)
-        builder.add_bool_branch(result, self.body_block, self.loop_exit)
 
-    def begin_body(self) -> None:
-        # The item is already assigned to self.index by the sub-generator.
-        pass
+        # Now, filter: only enter the body if func(item) is truthy
+        cont_block, rest_block = BasicBlock(), BasicBlock()
+        builder.add_bool_branch(result, rest_block, cont_block)
+        builder.activate_block(cont_block)
+        builder.nonlocal_control[-1].gen_continue(builder, line)
+        builder.goto_and_activate(rest_block)
+        # At this point, the rest of the loop body (user code) will be emitted
 
     def gen_step(self) -> None:
         self.gen.gen_step()
diff --git a/mypyc/test-data/irbuild-basic.test b/mypyc/test-data/irbuild-basic.test
index 4fb9869c9bf0..fe27d3f02486 100644
--- a/mypyc/test-data/irbuild-basic.test
+++ b/mypyc/test-data/irbuild-basic.test
@@ -3591,7 +3591,7 @@ L0:
 L1:
     r4 = var_object_size a
     r5 = r3 < r4 :: signed
-    if r5 goto L3 else goto L5 :: bool
+    if r5 goto L2 else goto L6 :: bool
 L2:
     r6 = list_get_item_unsafe a, r3
     r7 = unbox(int, r6)
@@ -3604,14 +3604,16 @@ L2:
     r12 = PyObject_IsTrue(r11)
     r13 = r12 >= 0 :: signed
     r14 = truncate r12: i32 to builtins.bool
-    if r14 goto L3 else goto L5 :: bool
+    if r14 goto L4 else goto L3 :: bool
 L3:
+    goto L5
+L4:
     r15 = CPyTagged_Add(s, x)
     s = r15
-L4:
+L5:
     r16 = r3 + 1
     r3 = r16
     goto L1
-L5:
 L6:
+L7:
     return s
diff --git a/mypyc/test-data/run-loops.test b/mypyc/test-data/run-loops.test
index 3f4de2f4c9cc..755ba04a6fbd 100644
--- a/mypyc/test-data/run-loops.test
+++ b/mypyc/test-data/run-loops.test
@@ -579,6 +579,8 @@ def f(a: list[int]) -> int:
         s += x
     return s
 
+[file driver.py]
+from native import f
 print(f([1, 2, 3, 4, 5, 6]))
 print(f([1, 3, 5]))
 print(f([]))
@@ -595,6 +597,8 @@ def f(a: list[int]) -> int:
         s += x
     return s
 
+[file driver.py]
+from native import f
 print(f([5, 15, 25]))
 print(f([]))
 

From ddc13b8c647e8b2875f8af4579ce8d378496f210 Mon Sep 17 00:00:00 2001
From: "pre-commit-ci[bot]"
 <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Date: Tue, 12 Aug 2025 03:21:09 +0000
Subject: [PATCH 05/29] [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci
---
 mypyc/test-data/fixtures/ir.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mypyc/test-data/fixtures/ir.py b/mypyc/test-data/fixtures/ir.py
index cddd05ff5fe9..010aa8814756 100644
--- a/mypyc/test-data/fixtures/ir.py
+++ b/mypyc/test-data/fixtures/ir.py
@@ -418,7 +418,7 @@ def __new__(cls, func: Callable[[_T1], _S], iterable: Iterable[_T1], /) -> Self:
     def __new__(cls, func: Callable[[_T1, _T2], _S], iterable: Iterable[_T1], iter2: Iterable[_T2], /) -> Self: ...
     def __iter__(self) -> Self: ...
     def __next__(self) -> _S: ...
-    
+
 class filter(Generic[_T]):
     @overload
     def __new__(cls, function: None, iterable: Iterable[_T | None], /) -> Self: ...

From fc12ceab55f4c224d91d62a9f7a0bceff4b7a22f Mon Sep 17 00:00:00 2001
From: BobTheBuidler <bobthebuidlerdefi@gmail.com>
Date: Tue, 12 Aug 2025 03:58:07 +0000
Subject: [PATCH 06/29] test with None

---
 mypyc/irbuild/for_helpers.py       | 13 +++++++--
 mypyc/test-data/irbuild-basic.test | 44 ++++++++++++++++++++++++++++++
 mypyc/test-data/run-loops.test     | 14 ++++++++++
 3 files changed, 68 insertions(+), 3 deletions(-)

diff --git a/mypyc/irbuild/for_helpers.py b/mypyc/irbuild/for_helpers.py
index c71a7c276510..2a61dbbdc345 100644
--- a/mypyc/irbuild/for_helpers.py
+++ b/mypyc/irbuild/for_helpers.py
@@ -22,6 +22,7 @@
     SetExpr,
     TupleExpr,
     TypeAlias,
+    Var,
 )
 from mypyc.ir.ops import (
     ERR_NEVER,
@@ -1168,7 +1169,10 @@ def need_cleanup(self) -> bool:
         return True
 
     def init(self, index: Lvalue, func: Expression, iterable: Expression) -> None:
-        self.filter_func = self.builder.accept(func)
+        if isinstance(func, NameExpr) and isinstance(func.node, Var) and func.node.fullname == "builtins.None":
+            self.filter_func = None
+        else:
+            self.filter_func = self.builder.accept(func)
         self.iterable = iterable
         self.index = index
 
@@ -1194,8 +1198,11 @@ def begin_body(self) -> None:
         builder = self.builder
         line = self.line
         item = builder.read(builder.get_assignment_target(self.index), line)
-        # TODO: implement logic to handle c calls of native functions
-        result = builder.py_call(self.filter_func, [item], line)
+        if self.filter_func is None:
+            result = item
+        else:
+            # TODO: implement logic to handle c calls of native functions
+            result = builder.py_call(self.filter_func, [item], line)
 
         # Now, filter: only enter the body if func(item) is truthy
         cont_block, rest_block = BasicBlock(), BasicBlock()
diff --git a/mypyc/test-data/irbuild-basic.test b/mypyc/test-data/irbuild-basic.test
index fe27d3f02486..5d257f0adac2 100644
--- a/mypyc/test-data/irbuild-basic.test
+++ b/mypyc/test-data/irbuild-basic.test
@@ -3617,3 +3617,47 @@ L5:
 L6:
 L7:
     return s
+
+[case testForFilterNone]
+def f(a: list[int]) -> int:
+    c = 0
+    for x in filter(None, a):
+        c += 1
+    return 0
+
+[out]
+def f(a):
+    a :: list
+    c :: int
+    r0, r1 :: native_int
+    r2 :: bit
+    r3 :: object
+    r4, x :: int
+    r5 :: bit
+    r6 :: int
+    r7 :: native_int
+L0:
+    c = 0
+    r0 = 0
+L1:
+    r1 = var_object_size a
+    r2 = r0 < r1 :: signed
+    if r2 goto L2 else goto L6 :: bool
+L2:
+    r3 = list_get_item_unsafe a, r0
+    r4 = unbox(int, r3)
+    x = r4
+    r5 = x != 0
+    if r5 goto L4 else goto L3 :: bool
+L3:
+    goto L5
+L4:
+    r6 = CPyTagged_Add(c, 2)
+    c = r6
+L5:
+    r7 = r0 + 1
+    r0 = r7
+    goto L1
+L6:
+L7:
+    return 0
diff --git a/mypyc/test-data/run-loops.test b/mypyc/test-data/run-loops.test
index 755ba04a6fbd..497b9254eda9 100644
--- a/mypyc/test-data/run-loops.test
+++ b/mypyc/test-data/run-loops.test
@@ -590,6 +590,20 @@ print(f([]))
 0
 0
 
+[case testRunForFilterNone]
+def f(a: list[int]) -> int:
+    c = 0
+    for x in filter(None, a):
+        c += 1
+    return c
+
+[file driver.py]
+from native import f
+print(f([0, 1, 2, 3, 4, 5, 6]))
+
+[out]
+6
+
 [case testRunForFilterEdgeCases]
 def f(a: list[int]) -> int:
     s = 0

From 54ad04e6ada62aacf88f83808c7642bc13040a5e Mon Sep 17 00:00:00 2001
From: "pre-commit-ci[bot]"
 <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Date: Tue, 12 Aug 2025 03:59:44 +0000
Subject: [PATCH 07/29] [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci
---
 mypyc/irbuild/for_helpers.py | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/mypyc/irbuild/for_helpers.py b/mypyc/irbuild/for_helpers.py
index 2a61dbbdc345..185e56700033 100644
--- a/mypyc/irbuild/for_helpers.py
+++ b/mypyc/irbuild/for_helpers.py
@@ -1169,7 +1169,11 @@ def need_cleanup(self) -> bool:
         return True
 
     def init(self, index: Lvalue, func: Expression, iterable: Expression) -> None:
-        if isinstance(func, NameExpr) and isinstance(func.node, Var) and func.node.fullname == "builtins.None":
+        if (
+            isinstance(func, NameExpr)
+            and isinstance(func.node, Var)
+            and func.node.fullname == "builtins.None"
+        ):
             self.filter_func = None
         else:
             self.filter_func = self.builder.accept(func)

From eae92092c66ec40049f43272454ea2052087f538 Mon Sep 17 00:00:00 2001
From: BobTheBuidler <bobthebuidlerdefi@gmail.com>
Date: Tue, 12 Aug 2025 15:06:09 +0000
Subject: [PATCH 08/29] IR cases for testing C calls

---
 mypyc/test-data/irbuild-basic.test | 142 ++++++++++++++++++++++++++++-
 1 file changed, 141 insertions(+), 1 deletion(-)

diff --git a/mypyc/test-data/irbuild-basic.test b/mypyc/test-data/irbuild-basic.test
index 5d257f0adac2..5b2a634cbf43 100644
--- a/mypyc/test-data/irbuild-basic.test
+++ b/mypyc/test-data/irbuild-basic.test
@@ -3547,7 +3547,7 @@ L0:
     r3 = box(None, 1)
     return r3
 
-[case testForFilter]
+[case testForFilterBool]
 def f(x: int) -> bool:
     return bool(x % 2)
 def g(a: list[int]) -> int:
@@ -3618,6 +3618,146 @@ L6:
 L7:
     return s
 
+[case testForFilterInt]
+def f(x: int) -> int:
+    return x % 2
+def g(a: list[int]) -> int:
+    s = 0
+    for x in filter(f, a):
+        s += x
+    return s
+[out]
+def f(x):
+    x, r0 :: int
+L0:
+    r0 = CPyTagged_Remainder(x, 4)
+    return r0
+def g(a):
+    a :: list
+    s :: int
+    r0 :: dict
+    r1 :: str
+    r2 :: object
+    r3, r4 :: native_int
+    r5 :: bit
+    r6 :: object
+    r7, x :: int
+    r8 :: object
+    r9 :: object[1]
+    r10 :: object_ptr
+    r11 :: object
+    r12 :: i32
+    r13 :: bit
+    r14 :: bool
+    r15 :: int
+    r16 :: native_int
+L0:
+    s = 0
+    r0 = __main__.globals :: static
+    r1 = 'f'
+    r2 = CPyDict_GetItem(r0, r1)
+    r3 = 0
+L1:
+    r4 = var_object_size a
+    r5 = r3 < r4 :: signed
+    if r5 goto L2 else goto L6 :: bool
+L2:
+    r6 = list_get_item_unsafe a, r3
+    r7 = unbox(int, r6)
+    x = r7
+    r8 = box(int, x)
+    r9 = [r8]
+    r10 = load_address r9
+    r11 = PyObject_Vectorcall(r2, r10, 1, 0)
+    keep_alive r8
+    r12 = PyObject_IsTrue(r11)
+    r13 = r12 >= 0 :: signed
+    r14 = truncate r12: i32 to builtins.bool
+    if r14 goto L4 else goto L3 :: bool
+L3:
+    goto L5
+L4:
+    r15 = CPyTagged_Add(s, x)
+    s = r15
+L5:
+    r16 = r3 + 1
+    r3 = r16
+    goto L1
+L6:
+L7:
+    return s
+
+[case testForFilterStr]
+def f(x: int) -> str:
+    return str(x % 2)
+def g(a: list[int]) -> int:
+    s = 0
+    for x in filter(f, a):
+        s += x
+    return s
+[out]
+def f(x):
+    x, r0 :: int
+    r1 :: str
+L0:
+    r0 = CPyTagged_Remainder(x, 4)
+    r1 = CPyTagged_Str(r0)
+    return r1
+def g(a):
+    a :: list
+    s :: int
+    r0 :: dict
+    r1 :: str
+    r2 :: object
+    r3, r4 :: native_int
+    r5 :: bit
+    r6 :: object
+    r7, x :: int
+    r8 :: object
+    r9 :: object[1]
+    r10 :: object_ptr
+    r11 :: object
+    r12 :: i32
+    r13 :: bit
+    r14 :: bool
+    r15 :: int
+    r16 :: native_int
+L0:
+    s = 0
+    r0 = __main__.globals :: static
+    r1 = 'f'
+    r2 = CPyDict_GetItem(r0, r1)
+    r3 = 0
+L1:
+    r4 = var_object_size a
+    r5 = r3 < r4 :: signed
+    if r5 goto L2 else goto L6 :: bool
+L2:
+    r6 = list_get_item_unsafe a, r3
+    r7 = unbox(int, r6)
+    x = r7
+    r8 = box(int, x)
+    r9 = [r8]
+    r10 = load_address r9
+    r11 = PyObject_Vectorcall(r2, r10, 1, 0)
+    keep_alive r8
+    r12 = PyObject_IsTrue(r11)
+    r13 = r12 >= 0 :: signed
+    r14 = truncate r12: i32 to builtins.bool
+    if r14 goto L4 else goto L3 :: bool
+L3:
+    goto L5
+L4:
+    r15 = CPyTagged_Add(s, x)
+    s = r15
+L5:
+    r16 = r3 + 1
+    r3 = r16
+    goto L1
+L6:
+L7:
+    return s
+
 [case testForFilterNone]
 def f(a: list[int]) -> int:
     c = 0

From 9941d54d895ceb7d13ebef4e6dd0e28f93142ac5 Mon Sep 17 00:00:00 2001
From: BobTheBuidler <bobthebuidlerdefi@gmail.com>
Date: Tue, 12 Aug 2025 16:34:42 +0000
Subject: [PATCH 09/29] feat: handle native calls and primitive ops

---
 mypyc/irbuild/for_helpers.py       | 20 ++++--
 mypyc/test-data/irbuild-basic.test | 98 ++++++++++--------------------
 2 files changed, 46 insertions(+), 72 deletions(-)

diff --git a/mypyc/irbuild/for_helpers.py b/mypyc/irbuild/for_helpers.py
index 2a61dbbdc345..03b6d1c74004 100644
--- a/mypyc/irbuild/for_helpers.py
+++ b/mypyc/irbuild/for_helpers.py
@@ -1169,10 +1169,11 @@ def need_cleanup(self) -> bool:
         return True
 
     def init(self, index: Lvalue, func: Expression, iterable: Expression) -> None:
+        self.filter_func_def = func
         if isinstance(func, NameExpr) and isinstance(func.node, Var) and func.node.fullname == "builtins.None":
-            self.filter_func = None
+            self.filter_func_val = None
         else:
-            self.filter_func = self.builder.accept(func)
+            self.filter_func_val = self.builder.accept(func)
         self.iterable = iterable
         self.index = index
 
@@ -1198,11 +1199,20 @@ def begin_body(self) -> None:
         builder = self.builder
         line = self.line
         item = builder.read(builder.get_assignment_target(self.index), line)
-        if self.filter_func is None:
+
+        if self.filter_func_val is None:
             result = item
         else:
-            # TODO: implement logic to handle c calls of native functions
-            result = builder.py_call(self.filter_func, [item], line)
+            fake_call_expr = CallExpr(
+                self.filter_func_def,
+                [
+                    # this is unused in call_refexpr_with_args which is good because
+                    # we don't have an Expression to put here. But it works just fine.
+                ],
+                [ARG_POS],
+                [None],
+            )
+            result = builder.call_refexpr_with_args(fake_call_expr, self.filter_func_def, [item])
 
         # Now, filter: only enter the body if func(item) is truthy
         cont_block, rest_block = BasicBlock(), BasicBlock()
diff --git a/mypyc/test-data/irbuild-basic.test b/mypyc/test-data/irbuild-basic.test
index 5b2a634cbf43..cd8a992e0b01 100644
--- a/mypyc/test-data/irbuild-basic.test
+++ b/mypyc/test-data/irbuild-basic.test
@@ -3573,15 +3573,9 @@ def g(a):
     r5 :: bit
     r6 :: object
     r7, x :: int
-    r8 :: object
-    r9 :: object[1]
-    r10 :: object_ptr
-    r11 :: object
-    r12 :: i32
-    r13 :: bit
-    r14 :: bool
-    r15 :: int
-    r16 :: native_int
+    r8 :: bool
+    r9 :: int
+    r10 :: native_int
 L0:
     s = 0
     r0 = __main__.globals :: static
@@ -3596,23 +3590,16 @@ L2:
     r6 = list_get_item_unsafe a, r3
     r7 = unbox(int, r6)
     x = r7
-    r8 = box(int, x)
-    r9 = [r8]
-    r10 = load_address r9
-    r11 = PyObject_Vectorcall(r2, r10, 1, 0)
-    keep_alive r8
-    r12 = PyObject_IsTrue(r11)
-    r13 = r12 >= 0 :: signed
-    r14 = truncate r12: i32 to builtins.bool
-    if r14 goto L4 else goto L3 :: bool
+    r8 = f(x)
+    if r8 goto L4 else goto L3 :: bool
 L3:
     goto L5
 L4:
-    r15 = CPyTagged_Add(s, x)
-    s = r15
+    r9 = CPyTagged_Add(s, x)
+    s = r9
 L5:
-    r16 = r3 + 1
-    r3 = r16
+    r10 = r3 + 1
+    r3 = r10
     goto L1
 L6:
 L7:
@@ -3641,16 +3628,10 @@ def g(a):
     r3, r4 :: native_int
     r5 :: bit
     r6 :: object
-    r7, x :: int
-    r8 :: object
-    r9 :: object[1]
-    r10 :: object_ptr
-    r11 :: object
-    r12 :: i32
-    r13 :: bit
-    r14 :: bool
-    r15 :: int
-    r16 :: native_int
+    r7, x, r8 :: int
+    r9 :: bit
+    r10 :: int
+    r11 :: native_int
 L0:
     s = 0
     r0 = __main__.globals :: static
@@ -3665,23 +3646,17 @@ L2:
     r6 = list_get_item_unsafe a, r3
     r7 = unbox(int, r6)
     x = r7
-    r8 = box(int, x)
-    r9 = [r8]
-    r10 = load_address r9
-    r11 = PyObject_Vectorcall(r2, r10, 1, 0)
-    keep_alive r8
-    r12 = PyObject_IsTrue(r11)
-    r13 = r12 >= 0 :: signed
-    r14 = truncate r12: i32 to builtins.bool
-    if r14 goto L4 else goto L3 :: bool
+    r8 = f(x)
+    r9 = r8 != 0
+    if r9 goto L4 else goto L3 :: bool
 L3:
     goto L5
 L4:
-    r15 = CPyTagged_Add(s, x)
-    s = r15
+    r10 = CPyTagged_Add(s, x)
+    s = r10
 L5:
-    r16 = r3 + 1
-    r3 = r16
+    r11 = r3 + 1
+    r3 = r11
     goto L1
 L6:
 L7:
@@ -3713,15 +3688,10 @@ def g(a):
     r5 :: bit
     r6 :: object
     r7, x :: int
-    r8 :: object
-    r9 :: object[1]
-    r10 :: object_ptr
-    r11 :: object
-    r12 :: i32
-    r13 :: bit
-    r14 :: bool
-    r15 :: int
-    r16 :: native_int
+    r8 :: str
+    r9 :: bit
+    r10 :: int
+    r11 :: native_int
 L0:
     s = 0
     r0 = __main__.globals :: static
@@ -3736,23 +3706,17 @@ L2:
     r6 = list_get_item_unsafe a, r3
     r7 = unbox(int, r6)
     x = r7
-    r8 = box(int, x)
-    r9 = [r8]
-    r10 = load_address r9
-    r11 = PyObject_Vectorcall(r2, r10, 1, 0)
-    keep_alive r8
-    r12 = PyObject_IsTrue(r11)
-    r13 = r12 >= 0 :: signed
-    r14 = truncate r12: i32 to builtins.bool
-    if r14 goto L4 else goto L3 :: bool
+    r8 = f(x)
+    r9 = CPyStr_IsTrue(r8)
+    if r9 goto L4 else goto L3 :: bool
 L3:
     goto L5
 L4:
-    r15 = CPyTagged_Add(s, x)
-    s = r15
+    r10 = CPyTagged_Add(s, x)
+    s = r10
 L5:
-    r16 = r3 + 1
-    r3 = r16
+    r11 = r3 + 1
+    r3 = r11
     goto L1
 L6:
 L7:

From 5237f0b0f6ee567fd27ff5d332150174f41bd134 Mon Sep 17 00:00:00 2001
From: "pre-commit-ci[bot]"
 <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Date: Tue, 12 Aug 2025 16:36:51 +0000
Subject: [PATCH 10/29] [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci
---
 mypyc/irbuild/for_helpers.py | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/mypyc/irbuild/for_helpers.py b/mypyc/irbuild/for_helpers.py
index 03b6d1c74004..b38abdb8cf6b 100644
--- a/mypyc/irbuild/for_helpers.py
+++ b/mypyc/irbuild/for_helpers.py
@@ -1170,7 +1170,11 @@ def need_cleanup(self) -> bool:
 
     def init(self, index: Lvalue, func: Expression, iterable: Expression) -> None:
         self.filter_func_def = func
-        if isinstance(func, NameExpr) and isinstance(func.node, Var) and func.node.fullname == "builtins.None":
+        if (
+            isinstance(func, NameExpr)
+            and isinstance(func.node, Var)
+            and func.node.fullname == "builtins.None"
+        ):
             self.filter_func_val = None
         else:
             self.filter_func_val = self.builder.accept(func)

From d68b833802f5455ec8d5df0cbdca19aeb6d768c7 Mon Sep 17 00:00:00 2001
From: BobTheBuidler <70677534+BobTheBuidler@users.noreply.github.com>
Date: Tue, 12 Aug 2025 12:39:32 -0400
Subject: [PATCH 11/29] Update run-loops.test

---
 mypyc/test-data/run-loops.test | 30 ++++++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)

diff --git a/mypyc/test-data/run-loops.test b/mypyc/test-data/run-loops.test
index 497b9254eda9..29acaa2c91f6 100644
--- a/mypyc/test-data/run-loops.test
+++ b/mypyc/test-data/run-loops.test
@@ -604,6 +604,36 @@ print(f([0, 1, 2, 3, 4, 5, 6]))
 [out]
 6
 
+[case testRunForFilterNative]
+def f(x: int) -> int:
+    return x % 2
+def g(a: list[int]) -> int:
+    c = 0
+    for x in filter(f, a):
+        c += 1
+    return c
+
+[file driver.py]
+from native import g
+print(g([0, 1, 2, 3, 4, 5, 6]))
+
+[out]
+3
+
+[case testRunForFilterPrimitiveOp]
+def f(a: list[list[int]]) -> int:
+    c = 0
+    for x in filter(len, a):
+        c += 1
+    return c
+
+[file driver.py]
+from native import f
+print(f([[], [0, 1], [], [], [2, 3, 4], [5, 6]]))
+
+[out]
+3
+
 [case testRunForFilterEdgeCases]
 def f(a: list[int]) -> int:
     s = 0

From c9680dc93803a5ccf170a755889ca8c65039be0d Mon Sep 17 00:00:00 2001
From: BobTheBuidler <70677534+BobTheBuidler@users.noreply.github.com>
Date: Tue, 12 Aug 2025 12:56:41 -0400
Subject: [PATCH 12/29] Update for_helpers.py

---
 mypyc/irbuild/for_helpers.py | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/mypyc/irbuild/for_helpers.py b/mypyc/irbuild/for_helpers.py
index b38abdb8cf6b..36c8fa6687c2 100644
--- a/mypyc/irbuild/for_helpers.py
+++ b/mypyc/irbuild/for_helpers.py
@@ -1164,9 +1164,7 @@ class ForFilter(ForGenerator):
     """Generate optimized IR for a for loop over filter(f, iterable)."""
 
     def need_cleanup(self) -> bool:
-        # The wrapped for loops might need cleanup. We might generate a
-        # redundant cleanup block, but that's okay.
-        return True
+        return self.gen.need_cleanup()
 
     def init(self, index: Lvalue, func: Expression, iterable: Expression) -> None:
         self.filter_func_def = func

From 5bf4b220dff27380cdfda965fd15e2735dd3984f Mon Sep 17 00:00:00 2001
From: BobTheBuidler <bobthebuidlerdefi@gmail.com>
Date: Tue, 12 Aug 2025 17:01:50 +0000
Subject: [PATCH 13/29] test primitive op

---
 mypyc/test-data/irbuild-basic.test | 58 ++++++++++++++++++++++++++++++
 1 file changed, 58 insertions(+)

diff --git a/mypyc/test-data/irbuild-basic.test b/mypyc/test-data/irbuild-basic.test
index cd8a992e0b01..8caa06a1011d 100644
--- a/mypyc/test-data/irbuild-basic.test
+++ b/mypyc/test-data/irbuild-basic.test
@@ -3722,6 +3722,64 @@ L6:
 L7:
     return s
 
+[case testForFilterPrimitiveOp]
+def f(a: list[list[int]]) -> int:
+    s = 0
+    for x in filter(len, a):
+        s += 1
+    return s
+[out]
+def f(a):
+    x, r0 :: int
+    r1 :: str
+L0:
+    r0 = CPyTagged_Remainder(x, 4)
+    r1 = CPyTagged_Str(r0)
+    return r1
+def g(a):
+    a :: list
+    s :: int
+    r0 :: dict
+    r1 :: str
+    r2 :: object
+    r3, r4 :: native_int
+    r5 :: bit
+    r6 :: object
+    r7, x :: int
+    r8 :: str
+    r9 :: bit
+    r10 :: int
+    r11 :: native_int
+L0:
+    s = 0
+    r0 = __main__.globals :: static
+    r1 = 'f'
+    r2 = CPyDict_GetItem(r0, r1)
+    r3 = 0
+L1:
+    r4 = var_object_size a
+    r5 = r3 < r4 :: signed
+    if r5 goto L2 else goto L6 :: bool
+L2:
+    r6 = list_get_item_unsafe a, r3
+    r7 = unbox(int, r6)
+    x = r7
+    r8 = f(x)
+    r9 = CPyStr_IsTrue(r8)
+    if r9 goto L4 else goto L3 :: bool
+L3:
+    goto L5
+L4:
+    r10 = CPyTagged_Add(s, x)
+    s = r10
+L5:
+    r11 = r3 + 1
+    r3 = r11
+    goto L1
+L6:
+L7:
+    return s
+
 [case testForFilterNone]
 def f(a: list[int]) -> int:
     c = 0

From c39bb4a5a7a923e7720a7d2d82ea70b7ec623768 Mon Sep 17 00:00:00 2001
From: BobTheBuidler <bobthebuidlerdefi@gmail.com>
Date: Tue, 12 Aug 2025 17:28:21 +0000
Subject: [PATCH 14/29] feat: use speciailizers

---
 mypyc/irbuild/for_helpers.py       | 13 +++++----
 mypyc/test-data/irbuild-basic.test | 43 +++++++++++++-----------------
 2 files changed, 27 insertions(+), 29 deletions(-)

diff --git a/mypyc/irbuild/for_helpers.py b/mypyc/irbuild/for_helpers.py
index 03b6d1c74004..da415fd20285 100644
--- a/mypyc/irbuild/for_helpers.py
+++ b/mypyc/irbuild/for_helpers.py
@@ -1205,14 +1205,17 @@ def begin_body(self) -> None:
         else:
             fake_call_expr = CallExpr(
                 self.filter_func_def,
-                [
-                    # this is unused in call_refexpr_with_args which is good because
-                    # we don't have an Expression to put here. But it works just fine.
-                ],
+                [self.index],
                 [ARG_POS],
                 [None],
             )
-            result = builder.call_refexpr_with_args(fake_call_expr, self.filter_func_def, [item])
+
+            builder.types[fake_call_expr] = builder.types[self.index]
+
+            # I put this here to prevent a circular import
+            from mypyc.irbuild.expression import transform_call_expr
+
+            result = transform_call_expr(builder, fake_call_expr)
 
         # Now, filter: only enter the body if func(item) is truthy
         cont_block, rest_block = BasicBlock(), BasicBlock()
diff --git a/mypyc/test-data/irbuild-basic.test b/mypyc/test-data/irbuild-basic.test
index 8caa06a1011d..730bb458a692 100644
--- a/mypyc/test-data/irbuild-basic.test
+++ b/mypyc/test-data/irbuild-basic.test
@@ -3730,31 +3730,25 @@ def f(a: list[list[int]]) -> int:
     return s
 [out]
 def f(a):
-    x, r0 :: int
-    r1 :: str
-L0:
-    r0 = CPyTagged_Remainder(x, 4)
-    r1 = CPyTagged_Str(r0)
-    return r1
-def g(a):
     a :: list
     s :: int
-    r0 :: dict
+    r0 :: object
     r1 :: str
     r2 :: object
     r3, r4 :: native_int
     r5 :: bit
     r6 :: object
-    r7, x :: int
-    r8 :: str
-    r9 :: bit
-    r10 :: int
-    r11 :: native_int
+    r7, x :: list
+    r8 :: native_int
+    r9 :: short_int
+    r10 :: bit
+    r11 :: int
+    r12 :: native_int
 L0:
     s = 0
-    r0 = __main__.globals :: static
-    r1 = 'f'
-    r2 = CPyDict_GetItem(r0, r1)
+    r0 = builtins :: module
+    r1 = 'len'
+    r2 = CPyObject_GetAttr(r0, r1)
     r3 = 0
 L1:
     r4 = var_object_size a
@@ -3762,19 +3756,20 @@ L1:
     if r5 goto L2 else goto L6 :: bool
 L2:
     r6 = list_get_item_unsafe a, r3
-    r7 = unbox(int, r6)
+    r7 = cast(list, r6)
     x = r7
-    r8 = f(x)
-    r9 = CPyStr_IsTrue(r8)
-    if r9 goto L4 else goto L3 :: bool
+    r8 = var_object_size x
+    r9 = r8 << 1
+    r10 = r9 != 0
+    if r10 goto L4 else goto L3 :: bool
 L3:
     goto L5
 L4:
-    r10 = CPyTagged_Add(s, x)
-    s = r10
+    r11 = CPyTagged_Add(s, 2)
+    s = r11
 L5:
-    r11 = r3 + 1
-    r3 = r11
+    r12 = r3 + 1
+    r3 = r12
     goto L1
 L6:
 L7:

From 9dceb9a821886c236e82b1f07fb228cae67e1604 Mon Sep 17 00:00:00 2001
From: BobTheBuidler <bobthebuidlerdefi@gmail.com>
Date: Tue, 12 Aug 2025 17:29:19 +0000
Subject: [PATCH 15/29] Revert "Update for_helpers.py"

This reverts commit c9680dc93803a5ccf170a755889ca8c65039be0d.
---
 mypyc/irbuild/for_helpers.py | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/mypyc/irbuild/for_helpers.py b/mypyc/irbuild/for_helpers.py
index 694fd26e1aa9..00d04e760622 100644
--- a/mypyc/irbuild/for_helpers.py
+++ b/mypyc/irbuild/for_helpers.py
@@ -1164,7 +1164,9 @@ class ForFilter(ForGenerator):
     """Generate optimized IR for a for loop over filter(f, iterable)."""
 
     def need_cleanup(self) -> bool:
-        return self.gen.need_cleanup()
+        # The wrapped for loops might need cleanup. We might generate a
+        # redundant cleanup block, but that's okay.
+        return True
 
     def init(self, index: Lvalue, func: Expression, iterable: Expression) -> None:
         self.filter_func_def = func

From 7c8053fdff48d6a2b4b39066c4bd6f3fcf41bdbf Mon Sep 17 00:00:00 2001
From: "pre-commit-ci[bot]"
 <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Date: Tue, 12 Aug 2025 17:30:04 +0000
Subject: [PATCH 16/29] [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci
---
 mypyc/irbuild/for_helpers.py | 7 +------
 1 file changed, 1 insertion(+), 6 deletions(-)

diff --git a/mypyc/irbuild/for_helpers.py b/mypyc/irbuild/for_helpers.py
index 00d04e760622..0cf9fde66f39 100644
--- a/mypyc/irbuild/for_helpers.py
+++ b/mypyc/irbuild/for_helpers.py
@@ -1207,12 +1207,7 @@ def begin_body(self) -> None:
         if self.filter_func_val is None:
             result = item
         else:
-            fake_call_expr = CallExpr(
-                self.filter_func_def,
-                [self.index],
-                [ARG_POS],
-                [None],
-            )
+            fake_call_expr = CallExpr(self.filter_func_def, [self.index], [ARG_POS], [None])
 
             builder.types[fake_call_expr] = builder.types[self.index]
 

From 8aff832fdbdecd002bbd39e40e89dfa7c42b9e60 Mon Sep 17 00:00:00 2001
From: BobTheBuidler <bobthebuidlerdefi@gmail.com>
Date: Tue, 12 Aug 2025 19:24:04 +0000
Subject: [PATCH 17/29] add to docs

---
 mypyc/doc/native_operations.rst | 1 +
 1 file changed, 1 insertion(+)

diff --git a/mypyc/doc/native_operations.rst b/mypyc/doc/native_operations.rst
index 3255dbedd98a..c8f8cf3329ff 100644
--- a/mypyc/doc/native_operations.rst
+++ b/mypyc/doc/native_operations.rst
@@ -37,6 +37,7 @@ Functions
 * ``slice(start, stop, step)``
 * ``globals()``
 * ``sorted(obj)``
+* ``filter(fn, iterable)``
 
 Method decorators
 -----------------

From cec1a5d9637deafaba53ae21c6cefe85395b8bbc Mon Sep 17 00:00:00 2001
From: BobTheBuidler <70677534+BobTheBuidler@users.noreply.github.com>
Date: Wed, 13 Aug 2025 03:59:10 -0400
Subject: [PATCH 18/29] Update for_helpers.py

---
 mypyc/irbuild/for_helpers.py | 2 --
 1 file changed, 2 deletions(-)

diff --git a/mypyc/irbuild/for_helpers.py b/mypyc/irbuild/for_helpers.py
index 0cf9fde66f39..71b3e1d8c047 100644
--- a/mypyc/irbuild/for_helpers.py
+++ b/mypyc/irbuild/for_helpers.py
@@ -1209,8 +1209,6 @@ def begin_body(self) -> None:
         else:
             fake_call_expr = CallExpr(self.filter_func_def, [self.index], [ARG_POS], [None])
 
-            builder.types[fake_call_expr] = builder.types[self.index]
-
             # I put this here to prevent a circular import
             from mypyc.irbuild.expression import transform_call_expr
 

From 572793cd20d6aec307a2a48ef8ca977dc83a27fe Mon Sep 17 00:00:00 2001
From: BobTheBuidler <70677534+BobTheBuidler@users.noreply.github.com>
Date: Thu, 14 Aug 2025 03:00:11 -0400
Subject: [PATCH 19/29] Update native_operations.rst

---
 mypyc/doc/native_operations.rst | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/mypyc/doc/native_operations.rst b/mypyc/doc/native_operations.rst
index c8f8cf3329ff..4487bf8df121 100644
--- a/mypyc/doc/native_operations.rst
+++ b/mypyc/doc/native_operations.rst
@@ -37,7 +37,6 @@ Functions
 * ``slice(start, stop, step)``
 * ``globals()``
 * ``sorted(obj)``
-* ``filter(fn, iterable)``
 
 Method decorators
 -----------------
@@ -55,3 +54,5 @@ These variants of statements have custom implementations:
 * ``for ... in seq:`` (for loop over a sequence)
 * ``for ... in enumerate(...):``
 * ``for ... in zip(...):``
+* ``for ... in filter(...):``
+* ``for ... in itertools.filterfalse(...):``

From dbbbb579f774d20541d2d6e843e89c1f5a7eec9f Mon Sep 17 00:00:00 2001
From: BobTheBuidler <70677534+BobTheBuidler@users.noreply.github.com>
Date: Sat, 16 Aug 2025 10:40:34 -0400
Subject: [PATCH 20/29] Update for_helpers.py

---
 mypyc/irbuild/for_helpers.py | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/mypyc/irbuild/for_helpers.py b/mypyc/irbuild/for_helpers.py
index 58bd74b271c9..1afdcee27026 100644
--- a/mypyc/irbuild/for_helpers.py
+++ b/mypyc/irbuild/for_helpers.py
@@ -1229,9 +1229,10 @@ def begin_body(self) -> None:
             fake_call_expr = CallExpr(self.filter_func_def, [self.index], [ARG_POS], [None])
 
             # I put this here to prevent a circular import
-            from mypyc.irbuild.expression import transform_call_expr
+            #from mypyc.irbuild.expression import transform_call_expr
 
-            result = transform_call_expr(builder, fake_call_expr)
+            #result = transform_call_expr(builder, fake_call_expr)
+            resulr = builder.accept(fake_call_expr)
 
         # Now, filter: only enter the body if func(item) is truthy
         cont_block, rest_block = BasicBlock(), BasicBlock()

From 0bc1d26c1ffd204724c64950813c686bf712e306 Mon Sep 17 00:00:00 2001
From: "pre-commit-ci[bot]"
 <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Date: Sat, 16 Aug 2025 14:41:52 +0000
Subject: [PATCH 21/29] [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci
---
 mypyc/irbuild/for_helpers.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/mypyc/irbuild/for_helpers.py b/mypyc/irbuild/for_helpers.py
index 1afdcee27026..e9761c0cb1a8 100644
--- a/mypyc/irbuild/for_helpers.py
+++ b/mypyc/irbuild/for_helpers.py
@@ -1229,9 +1229,9 @@ def begin_body(self) -> None:
             fake_call_expr = CallExpr(self.filter_func_def, [self.index], [ARG_POS], [None])
 
             # I put this here to prevent a circular import
-            #from mypyc.irbuild.expression import transform_call_expr
+            # from mypyc.irbuild.expression import transform_call_expr
 
-            #result = transform_call_expr(builder, fake_call_expr)
+            # result = transform_call_expr(builder, fake_call_expr)
             resulr = builder.accept(fake_call_expr)
 
         # Now, filter: only enter the body if func(item) is truthy

From 7d56fa9d0ceb46cc8438cf6ff0ed4654b77d7935 Mon Sep 17 00:00:00 2001
From: BobTheBuidler <70677534+BobTheBuidler@users.noreply.github.com>
Date: Sat, 16 Aug 2025 10:46:25 -0400
Subject: [PATCH 22/29] Update for_helpers.py

---
 mypyc/irbuild/for_helpers.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mypyc/irbuild/for_helpers.py b/mypyc/irbuild/for_helpers.py
index e9761c0cb1a8..386c543a3c22 100644
--- a/mypyc/irbuild/for_helpers.py
+++ b/mypyc/irbuild/for_helpers.py
@@ -1232,7 +1232,7 @@ def begin_body(self) -> None:
             # from mypyc.irbuild.expression import transform_call_expr
 
             # result = transform_call_expr(builder, fake_call_expr)
-            resulr = builder.accept(fake_call_expr)
+            result = builder.accept(fake_call_expr)
 
         # Now, filter: only enter the body if func(item) is truthy
         cont_block, rest_block = BasicBlock(), BasicBlock()

From 11b04c353845efabb3632f53b9b5e21bd81b87fd Mon Sep 17 00:00:00 2001
From: BobTheBuidler <70677534+BobTheBuidler@users.noreply.github.com>
Date: Sun, 7 Sep 2025 01:49:55 -0400
Subject: [PATCH 23/29] Update ir.py

---
 mypyc/test-data/fixtures/ir.py | 8 --------
 1 file changed, 8 deletions(-)

diff --git a/mypyc/test-data/fixtures/ir.py b/mypyc/test-data/fixtures/ir.py
index cf9325c3b2c3..77602cc26103 100644
--- a/mypyc/test-data/fixtures/ir.py
+++ b/mypyc/test-data/fixtures/ir.py
@@ -416,14 +416,6 @@ class staticmethod: pass
 _T1 = TypeVar("_T1")
 _T2 = TypeVar("_T2")
 
-class map(Generic[_S]):
-    @overload
-    def __new__(cls, func: Callable[[_T1], _S], iterable: Iterable[_T1], /) -> Self: ...
-    @overload
-    def __new__(cls, func: Callable[[_T1, _T2], _S], iterable: Iterable[_T1], iter2: Iterable[_T2], /) -> Self: ...
-    def __iter__(self) -> Self: ...
-    def __next__(self) -> _S: ...
-
 class filter(Generic[_T]):
     @overload
     def __new__(cls, function: None, iterable: Iterable[_T | None], /) -> Self: ...

From fa54df2b29a80e7eeb1e9004e26b21c08b0b9f9e Mon Sep 17 00:00:00 2001
From: BobTheBuidler <70677534+BobTheBuidler@users.noreply.github.com>
Date: Sun, 7 Sep 2025 01:50:23 -0400
Subject: [PATCH 24/29] Update ir.py

---
 mypyc/test-data/fixtures/ir.py | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/mypyc/test-data/fixtures/ir.py b/mypyc/test-data/fixtures/ir.py
index 77602cc26103..4ac24f8834b1 100644
--- a/mypyc/test-data/fixtures/ir.py
+++ b/mypyc/test-data/fixtures/ir.py
@@ -413,9 +413,6 @@ class staticmethod: pass
 
 NotImplemented: Any = ...
 
-_T1 = TypeVar("_T1")
-_T2 = TypeVar("_T2")
-
 class filter(Generic[_T]):
     @overload
     def __new__(cls, function: None, iterable: Iterable[_T | None], /) -> Self: ...

From d2edf7b484b904616f43f64888a99edc27f82f30 Mon Sep 17 00:00:00 2001
From: BobTheBuidler <70677534+BobTheBuidler@users.noreply.github.com>
Date: Sun, 7 Sep 2025 01:50:58 -0400
Subject: [PATCH 25/29] Update native_operations.rst

---
 mypyc/doc/native_operations.rst | 1 -
 1 file changed, 1 deletion(-)

diff --git a/mypyc/doc/native_operations.rst b/mypyc/doc/native_operations.rst
index 4487bf8df121..3a6afba7872c 100644
--- a/mypyc/doc/native_operations.rst
+++ b/mypyc/doc/native_operations.rst
@@ -55,4 +55,3 @@ These variants of statements have custom implementations:
 * ``for ... in enumerate(...):``
 * ``for ... in zip(...):``
 * ``for ... in filter(...):``
-* ``for ... in itertools.filterfalse(...):``

From 715ce4694506fe2d88892462524583cef7a8d0ad Mon Sep 17 00:00:00 2001
From: BobTheBuidler <70677534+BobTheBuidler@users.noreply.github.com>
Date: Sun, 7 Sep 2025 01:58:15 -0400
Subject: [PATCH 26/29] refactor run tests

---
 mypyc/test-data/run-loops.test | 81 ++++++++++------------------------
 1 file changed, 23 insertions(+), 58 deletions(-)

diff --git a/mypyc/test-data/run-loops.test b/mypyc/test-data/run-loops.test
index 29acaa2c91f6..f701e1f18e98 100644
--- a/mypyc/test-data/run-loops.test
+++ b/mypyc/test-data/run-loops.test
@@ -578,74 +578,39 @@ def f(a: list[int]) -> int:
     for x in filter(lambda x: x % 2 == 0, a):
         s += x
     return s
-
-[file driver.py]
-from native import f
-print(f([1, 2, 3, 4, 5, 6]))
-print(f([1, 3, 5]))
-print(f([]))
-
-[out]
-12
-0
-0
-
-[case testRunForFilterNone]
-def f(a: list[int]) -> int:
+def g(a: list[int]) -> int:
+    s = 0
+    for x in filter(lambda x: x > 10, a):
+        s += x
+    return s
+def with_none(a: list[int]) -> int:
     c = 0
     for x in filter(None, a):
         c += 1
     return c
-
-[file driver.py]
-from native import f
-print(f([0, 1, 2, 3, 4, 5, 6]))
-
-[out]
-6
-
-[case testRunForFilterNative]
-def f(x: int) -> int:
+def native_func(x: int) -> int:
     return x % 2
-def g(a: list[int]) -> int:
+def with_native_func(a: list[int]) -> int:
     c = 0
-    for x in filter(f, a):
+    for x in filter(native_func, a):
         c += 1
     return c
-
-[file driver.py]
-from native import g
-print(g([0, 1, 2, 3, 4, 5, 6]))
-
-[out]
-3
-
-[case testRunForFilterPrimitiveOp]
-def f(a: list[list[int]]) -> int:
+def with_primitive(a: list[list[int]]) -> int:
     c = 0
     for x in filter(len, a):
         c += 1
     return c
 
-[file driver.py]
-from native import f
-print(f([[], [0, 1], [], [], [2, 3, 4], [5, 6]]))
-
-[out]
-3
-
-[case testRunForFilterEdgeCases]
-def f(a: list[int]) -> int:
-    s = 0
-    for x in filter(lambda x: x > 10, a):
-        s += x
-    return s
-
-[file driver.py]
-from native import f
-print(f([5, 15, 25]))
-print(f([]))
-
-[out]
-40
-0
+def test_run_for_filter() -> None:
+    assert f([1, 2, 3, 4, 5, 6]) == 12
+    assert f([1, 3, 5]) == 0
+    assert f([]) == 0
+def test_run_for_filter_with_none() -> None:
+    assert with_none([0, 1, 2, 3, 4, 5, 6]) == 6
+def test_run_for_filter_with_native_func() -> None:
+    assert with_native_func([0, 1, 2, 3, 4, 5, 6]) == 3
+def test_run_for_filter_with_primitive() -> None:
+    assert with_primitive([[], [0, 1], [], [], [2, 3, 4], [5, 6]]) == 3
+def test_run_for_filter_edge_cases() -> None:
+    assert g([5, 15, 25]) == 40
+    assert g([]) == 0

From a3b65b3263d4f81e716ef6faade10fe582c436d5 Mon Sep 17 00:00:00 2001
From: BobTheBuidler <70677534+BobTheBuidler@users.noreply.github.com>
Date: Mon, 8 Sep 2025 10:23:57 -0400
Subject: [PATCH 27/29] Update mypyc/test-data/fixtures/ir.py

oh, whoops!

Co-authored-by: Brian Schubert <brianm.schubert@gmail.com>
---
 mypyc/test-data/fixtures/ir.py | 2 --
 1 file changed, 2 deletions(-)

diff --git a/mypyc/test-data/fixtures/ir.py b/mypyc/test-data/fixtures/ir.py
index 4ac24f8834b1..ee8ec6d131f3 100644
--- a/mypyc/test-data/fixtures/ir.py
+++ b/mypyc/test-data/fixtures/ir.py
@@ -7,8 +7,6 @@
     overload, Mapping, Union, Callable, Sequence, FrozenSet, Protocol
 )
 
-from typing_extensions import Self
-
 _T = TypeVar('_T')
 T_co = TypeVar('T_co', covariant=True)
 T_contra = TypeVar('T_contra', contravariant=True)

From 1197e4e7fdd7d516691dff211b3b3519a5a9c026 Mon Sep 17 00:00:00 2001
From: BobTheBuidler <70677534+BobTheBuidler@users.noreply.github.com>
Date: Sun, 28 Sep 2025 15:43:40 -0400
Subject: [PATCH 28/29] fix ir generaton

---
 mypyc/irbuild/for_helpers.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/mypyc/irbuild/for_helpers.py b/mypyc/irbuild/for_helpers.py
index 698502941b8d..4905c7bf442d 100644
--- a/mypyc/irbuild/for_helpers.py
+++ b/mypyc/irbuild/for_helpers.py
@@ -1242,8 +1242,8 @@ def begin_body(self) -> None:
             # I put this here to prevent a circular import
             # from mypyc.irbuild.expression import transform_call_expr
 
-            # result = transform_call_expr(builder, fake_call_expr)
-            result = builder.accept(fake_call_expr)
+            result = transform_call_expr(builder, fake_call_expr)
+            # result = builder.accept(fake_call_expr)
 
         # Now, filter: only enter the body if func(item) is truthy
         cont_block, rest_block = BasicBlock(), BasicBlock()

From 75f61e3b86640ad087cd33a4d6da8de6a7bb22f5 Mon Sep 17 00:00:00 2001
From: BobTheBuidler <70677534+BobTheBuidler@users.noreply.github.com>
Date: Sun, 28 Sep 2025 15:46:26 -0400
Subject: [PATCH 29/29] Update for_helpers.py

---
 mypyc/irbuild/for_helpers.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mypyc/irbuild/for_helpers.py b/mypyc/irbuild/for_helpers.py
index 4905c7bf442d..4078b6238191 100644
--- a/mypyc/irbuild/for_helpers.py
+++ b/mypyc/irbuild/for_helpers.py
@@ -1240,7 +1240,7 @@ def begin_body(self) -> None:
             fake_call_expr = CallExpr(self.filter_func_def, [self.index], [ARG_POS], [None])
 
             # I put this here to prevent a circular import
-            # from mypyc.irbuild.expression import transform_call_expr
+            from mypyc.irbuild.expression import transform_call_expr
 
             result = transform_call_expr(builder, fake_call_expr)
             # result = builder.accept(fake_call_expr)