From 999c2314c0d649646a53e7cc440ae3f4aa1a3d61 Mon Sep 17 00:00:00 2001
From: Akshay Nair <phenax5@gmail.com>
Date: Tue, 12 Dec 2023 18:47:06 +0530
Subject: feat: commutativity + identity for multiplication

---
 src/util.ts | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

(limited to 'src/util.ts')

diff --git a/src/util.ts b/src/util.ts
index f6067ae..97e9335 100644
--- a/src/util.ts
+++ b/src/util.ts
@@ -13,7 +13,8 @@ export type ApplyRewrite<O extends Op, R extends Rewrite<Op, Op>> =
   : O extends string ? O
   : O extends { a: Op, b: Op, op: string } ? (
     ApplyRewrite<O['a'], R> extends O['a']
-    ? Omit<O, 'b'> & { b: ApplyRewrite<O['b'], R> }
+    ? (ApplyRewrite<O['b'], R> extends O['b'] ? O
+      : Omit<O, 'b'> & { b: ApplyRewrite<O['b'], R> })
     : Omit<O, 'a'> & { a: ApplyRewrite<O['a'], R> }
   )
   : never;
@@ -33,6 +34,7 @@ export type ChainRewrites<Rws extends Rewrite<Op, Op>[], O extends Op> =
 export type VerifyEquation<Eq extends Rewrite<Op, Op>> =
   Eq['right'] extends 'true' ? true : false & Eq['right'];
 
+export type assert<T extends true> = T;
 export type Eq<a, b> = ([a] extends [b] ? ([b] extends [a] ? true : false & { lhs: a; rhs: b }) : false & { lhs: a; rhs: b });
 
 export type Equation<A extends Op, B extends Op> = { op: '=', a: A, b: B };
-- 
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