From cad7dc6904b05d53e9e9ce72aea47fb411d8b3aa Mon Sep 17 00:00:00 2001
From: Nicholas Ward <npward@berkeley.edu>
Date: Wed, 30 Jun 2021 21:31:17 -0700
Subject: [PATCH] some progress

---
 src/gadgets/insert.rs | 19 +++++++++++++++++--
 1 file changed, 17 insertions(+), 2 deletions(-)

diff --git a/src/gadgets/insert.rs b/src/gadgets/insert.rs
index b7f7e331..4b6a15b1 100644
--- a/src/gadgets/insert.rs
+++ b/src/gadgets/insert.rs
@@ -2,11 +2,26 @@ use crate::circuit_builder::CircuitBuilder;
 use crate::field::extension_field::target::ExtensionTarget;
 use crate::field::extension_field::Extendable;
 use crate::target::Target;
+use crate::generator::EqualityGenerator;
 
 impl<F: Extendable<D>, const D: usize> CircuitBuilder<F, D> {
+    /// Evaluates to 1 if `x` equals zero, 0 otherwise.
+    pub fn is_zero(&mut self, x: Target) -> Target {
+        let m = todo!();
+        let y = todo!();
+
+        self.add_generator(EqualityGenerator {
+            x,
+            m,
+            y,
+        });
+
+        y
+    }
+
     /// Evaluates to 1 if `x` and `y` are equal, 0 otherwise.
-    pub fn is_equal(&mut self, _x: Target, _y: Target) -> Target {
-        todo!()
+    pub fn is_equal(&mut self, x: Target, y: Target) -> Target {
+        self.is_zero(self.sub(x, y))
     }
 
     /// Inserts a `Target` in a vector at a non-deterministic index. This is done by rotating to the