Fix resolveState

strudel.mjs

@@ -182,7 +182,7 @@ class Hap {
         this.context = context
         this.stateful = stateful
         if (stateful) {
-            assert(typeof this.value === "function", "Stateful values must be functions");
+            console.assert(typeof this.value === "function", "Stateful values must be functions");
         }
     }
 
@@ -205,9 +205,10 @@ class Hap {
 
     resolveState(state) {
         if (this.stateful && this.hasOnset()) {
+            console.log("stateful")
             const func = this.value
-            [newState, newValue] = func(state)
-            return [newState, this.withValue(() => newValue)]
+            const [newState, newValue] = func(state)
+            return [newState, new Hap(this.whole, this.part, newValue, this.context, false)]
         }
         return [state, this]
     }

test/pattern.test.mjs

@@ -58,6 +58,27 @@ describe('Hap', function() {
         assert.equal(d.spanEquals(e), true)
       })
     })
+    describe('resolveState()', () => {
+      it('Can increment some state', function() {
+        const stateful_value = state => {
+          const newValue = state["incrementme"]
+          // TODO Does the state *need* duplicating here?
+          const newState = {...state}
+          newState["incrementme"]++
+          return [newState, newValue]
+        }
+        const state = {incrementme: 10}
+        const ev1 = new Hap(ts(0,1), ts(0,1), stateful_value, {}, true)
+        const [state2, ev2] = ev1.resolveState(state)
+        const [state3, ev3] = ev1.resolveState(state2)
+        assert.deepStrictEqual(
+          ev3, new Hap(ts(0,1),ts(0,1),11,{},false)
+        )
+        assert.deepStrictEqual(
+          state3, {incrementme: 12}
+        )
+      })
+    })
   });
   
 describe('Pattern', function() {