From 320a6b82ea1e33822218e7c44be898bc4edd2a6f Mon Sep 17 00:00:00 2001
From: Charles Yuan <charlesyuan@google.com>
Date: Mon, 1 Jul 2024 18:34:59 -0700
Subject: [PATCH] Use symbolic prod and sum

---
 qualtran/bloqs/block_encoding/tensor_product.py | 6 +++---
 qualtran/symbolics/__init__.py                  | 1 +
 qualtran/symbolics/math_funcs.py                | 7 +++++++
 3 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/qualtran/bloqs/block_encoding/tensor_product.py b/qualtran/bloqs/block_encoding/tensor_product.py
index c440eceff..3a9bc992b 100644
--- a/qualtran/bloqs/block_encoding/tensor_product.py
+++ b/qualtran/bloqs/block_encoding/tensor_product.py
@@ -12,7 +12,7 @@
 #  See the License for the specific language governing permissions and
 #  limitations under the License.
 
-from functools import cached_property, reduce
+from functools import cached_property
 from typing import Dict, Set, Tuple, TYPE_CHECKING
 
 from attrs import evolve, field, frozen, validators
@@ -31,7 +31,7 @@
 from qualtran.bloqs.block_encoding.lcu_select_and_prepare import PrepareOracle
 from qualtran.bloqs.bookkeeping import Partition
 from qualtran.resource_counting import BloqCountT, SympySymbolAllocator
-from qualtran.symbolics import is_symbolic, SymbolicFloat, SymbolicInt
+from qualtran.symbolics import is_symbolic, prod, sum, SymbolicFloat, SymbolicInt
 
 
 @frozen
@@ -80,7 +80,7 @@ def pretty_name(self) -> str:
 
     @cached_property
     def alpha(self) -> SymbolicFloat:
-        return reduce(lambda a, b: a * b.alpha, self.block_encodings, 1.0)
+        return prod(u.alpha for u in self.block_encodings)
 
     @cached_property
     def ancilla_bitsize(self) -> SymbolicInt:
diff --git a/qualtran/symbolics/__init__.py b/qualtran/symbolics/__init__.py
index 10ad6bf00..848ebd51d 100644
--- a/qualtran/symbolics/__init__.py
+++ b/qualtran/symbolics/__init__.py
@@ -27,6 +27,7 @@
     slen,
     smax,
     smin,
+    sum,
 )
 from qualtran.symbolics.types import (
     HasLength,
diff --git a/qualtran/symbolics/math_funcs.py b/qualtran/symbolics/math_funcs.py
index a87929eb5..002d88500 100644
--- a/qualtran/symbolics/math_funcs.py
+++ b/qualtran/symbolics/math_funcs.py
@@ -97,6 +97,13 @@ def prod(args: Iterable[SymbolicT]) -> SymbolicT:
     return ret
 
 
+def sum(args: Iterable[SymbolicT]) -> SymbolicT:
+    ret: SymbolicT = 0
+    for arg in args:
+        ret = ret + arg
+    return ret
+
+
 def acos(x: SymbolicFloat) -> SymbolicFloat:
     if not isinstance(x, sympy.Basic):
         return np.arccos(x)