From 694162a7b1d0c916ffa76461bcb5fb77bf046459 Mon Sep 17 00:00:00 2001
From: Alex McLean <alex@slab.org>
Date: Wed, 8 Oct 2025 14:13:33 +0100
Subject: [PATCH] fix purity of 'withState' so it returns a new pattern

---
 packages/core/pattern.mjs | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/packages/core/pattern.mjs b/packages/core/pattern.mjs
index d0be3f599..72f6371b3 100644
--- a/packages/core/pattern.mjs
+++ b/packages/core/pattern.mjs
@@ -98,10 +98,7 @@ export class Pattern {
 
   // runs func on query state
   withState(func) {
-    return this.withHaps((haps, state) => {
-      func(state);
-      return haps;
-    });
+    return new Pattern((state) => this.query(func(state)));
   }
 
   /**