From 7e1e32bfbec7882c201f5346ae87702a41e46dcc Mon Sep 17 00:00:00 2001
From: skaunov <skaunov@gmail.com>
Date: Sun, 21 Jan 2024 10:16:11 +0300
Subject: [PATCH 1/2] Example for draft PR

Error handling is mocked just for example; return type for the modified
method have been left incompatible as it shows the idea to the point.
---
 src/lib.rs | 30 +++++++++++++++++++++++++-----
 1 file changed, 25 insertions(+), 5 deletions(-)

diff --git a/src/lib.rs b/src/lib.rs
index a2bdc104..d93c94c9 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,3 +1,4 @@
+#![feature(iterator_try_reduce)]
 #![cfg_attr(not(feature = "std"), no_std)]
 //! This crate implements common "gadgets" that make
 //! programming rank-1 constraint systems easier.
@@ -131,12 +132,31 @@ pub trait R1CSVar<F: Field> {
 impl<F: Field, T: R1CSVar<F>> R1CSVar<F> for [T] {
     type Value = Vec<T::Value>;
 
-    fn cs(&self) -> ark_relations::r1cs::ConstraintSystemRef<F> {
-        let mut result = ark_relations::r1cs::ConstraintSystemRef::None;
-        for var in self {
-            result = var.cs().or(result);
+    fn cs(&self) -> Result<ark_relations::r1cs::ConstraintSystemRef<F>, &str> {
+        if let Some(Ok(result)) = self.iter().map(|x| Ok(x.cs())).reduce(
+            |x: Result<ark_relations::r1cs::ConstraintSystemRef<F>, _>, y| {
+                if let Ok(x) = x {
+                    let y = y?;
+                    if x != y {
+                        if x.is_none() {
+                            return Ok(y);
+                        }
+                        if y.is_none() {
+                            return Ok(x);
+                        }
+                        Err("todo!(CSs are not reducible to one)")
+                    } else {
+                        return Ok(x);
+                    }
+                } else {
+                    x
+                }
+            },
+        ) {
+            Ok(result.to_owned())
+        } else {
+            Err("empty input")
         }
-        result
     }
 
     fn value(&self) -> Result<Self::Value, ark_relations::r1cs::SynthesisError> {

From ed11638adb4b057edc2b63b42dca1950f5d88100 Mon Sep 17 00:00:00 2001
From: skaunov <skaunov@gmail.com>
Date: Sun, 21 Jan 2024 10:40:32 +0300
Subject: [PATCH 2/2] Tiny cleaning of changes

---
 src/lib.rs | 1 -
 1 file changed, 1 deletion(-)

diff --git a/src/lib.rs b/src/lib.rs
index d93c94c9..c6072b0e 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,4 +1,3 @@
-#![feature(iterator_try_reduce)]
 #![cfg_attr(not(feature = "std"), no_std)]
 //! This crate implements common "gadgets" that make
 //! programming rank-1 constraint systems easier.