From 6841763ae70b9f91d440856f4a160d116c9edf6c Mon Sep 17 00:00:00 2001
From: Sean Bowe <ewillbefull@gmail.com>
Date: Thu, 28 Dec 2017 16:10:19 -0700
Subject: [PATCH] Add TODO for improving lookup performance.

---
 src/circuit/pedersen_hash.rs | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/circuit/pedersen_hash.rs b/src/circuit/pedersen_hash.rs
index 0989d84cf..c05d61724 100644
--- a/src/circuit/pedersen_hash.rs
+++ b/src/circuit/pedersen_hash.rs
@@ -131,6 +131,10 @@ fn lookup3_xy_with_conditional_negation<E: Engine, CS, Var: Copy>(
 ) -> Result<(AllocatedNum<E, Var>, AllocatedNum<E, Var>), SynthesisError>
     where CS: ConstraintSystem<E, Variable=Var>
 {
+    // TODO: This can be made into a 2-constraint lookup
+    // if it can return linear combinations rather than
+    // allocated numbers.
+
     assert_eq!(bits.len(), 3);
     assert_eq!(coords.len(), 4);