From 3d4a6b9bb61850ff1fe699c5a757b1c0cc49f940 Mon Sep 17 00:00:00 2001
From: Tony Garnock-Jones <tonyg@leastfixedpoint.com>
Date: Tue, 23 Feb 2021 11:13:41 +0100
Subject: [PATCH] Tighten

---
 actor.ts | 16 ++++++----------
 1 file changed, 6 insertions(+), 10 deletions(-)

diff --git a/actor.ts b/actor.ts
index 0a6de6f..c4f65f0 100644
--- a/actor.ts
+++ b/actor.ts
@@ -84,7 +84,12 @@ export class Turn {
 
     spawn(bootProc: (t: Turn) => void, initialAssertions = new IdentitySet<Handle>()): void {
         this.tasks.push(() => {
-            const child = new Actor(extractFromMap(this.actor.outbound, initialAssertions));
+            const newOutbound: OutboundMap = new Map();
+            initialAssertions.forEach(key => {
+                newOutbound.set(key, this.actor.outbound.get(key)!); // we trust initialAssertions
+                this.actor.outbound.delete(key);
+            });
+            const child = new Actor(newOutbound);
             child.execute(() => Turn.for(child, bootProc));
         });
     }
@@ -137,12 +142,3 @@ export class Turn {
         this.tasks.length && queueMicrotask(() => this.tasks.forEach(f => Turn.for(this.actor, f)));
     }
 }
-
-function extractFromMap<K, V>(map: Map<K, V>, keys: IdentitySet<K>): Map<K, V> {
-    const result: Map<K, V> = new Map();
-    keys.forEach(key => {
-        if (map.has(key)) result.set(key, map.get(key)!);
-        map.delete(key);
-    });
-    return result;
-}