From a7f5589881fe4e8881d4e29ef43fc299d6e1dcfb Mon Sep 17 00:00:00 2001
From: Tony Garnock-Jones <tonyg@leastfixedpoint.com>
Date: Mon, 22 Feb 2021 22:32:09 +0100
Subject: [PATCH] Tighten and simplify

---
 actor.ts | 18 +++++++-----------
 1 file changed, 7 insertions(+), 11 deletions(-)

diff --git a/actor.ts b/actor.ts
index 198cef6..5589333 100644
--- a/actor.ts
+++ b/actor.ts
@@ -92,10 +92,8 @@ export class Turn {
         return new Ref(this._ensureActor(what), t);
     }
 
-    spawn(bootProc: (t: Turn) => void, initialAssertions?: IdentitySet<Handle>): void {
-        if ((initialAssertions !== void 0) && (initialAssertions.size > 0)) {
-            this._ensureActor("spawn with initialAssertions");
-        }
+    spawn(bootProc: (t: Turn) => void, initialAssertions = new IdentitySet<Handle>()): void {
+        if (initialAssertions.size > 0) this._ensureActor("spawn with initialAssertions");
         this.localActions.push(() => {
             const child = new Actor(this.actor === null
                 ? void 0
@@ -157,13 +155,11 @@ export class Turn {
     }
 }
 
-function extractFromMap<K, V>(map: Map<K, V>, keys?: IdentitySet<K>): Map<K, V> {
+function extractFromMap<K, V>(map: Map<K, V>, keys: IdentitySet<K>): Map<K, V> {
     const result: Map<K, V> = new Map();
-    if (keys !== void 0) {
-        keys.forEach(key => {
-            if (map.has(key)) result.set(key, map.get(key)!);
-            map.delete(key);
-        });
-    }
+    keys.forEach(key => {
+        if (map.has(key)) result.set(key, map.get(key)!);
+        map.delete(key);
+    });
     return result;
 }