diff --git a/types/component-set.d.ts b/types/component-set.d.ts
new file mode 100644
index 0000000..a26bbe3
--- /dev/null
+++ b/types/component-set.d.ts
@@ -0,0 +1,8 @@
+/**
+ * Track an entity, component tuple as a unique key in a set.
+ */
+export function create(): any[];
+export function includes(set: any, entity: any, componentName: any): boolean;
+export function add(set: any, entity: any, componentName: any): void;
+export function remove(set: any, entity: any, componentName: any): void;
+//# sourceMappingURL=component-set.d.ts.map
\ No newline at end of file
diff --git a/types/component-set.d.ts.map b/types/component-set.d.ts.map
new file mode 100644
index 0000000..4daee8a
--- /dev/null
+++ b/types/component-set.d.ts.map
@@ -0,0 +1 @@
+{"version":3,"file":"component-set.d.ts","sourceRoot":"","sources":["../component-set.js"],"names":[],"mappings":"AAGA;;GAEG;AAEH,gCAEC;AAGD,6EAQC;AAGD,qEAEC;AAGD,wEAQC"}
\ No newline at end of file
diff --git a/types/ecs.d.ts b/types/ecs.d.ts
index dd99330..25c6077 100644
--- a/types/ecs.d.ts
+++ b/types/ecs.d.ts
@@ -49,9 +49,8 @@
  */
 /**
  * @typedef { Object } DeferredRemovalMap
- * @prop {number[]} entities indexes into entities array, sorted from highest to lowest
- * @prop {string[]} components [ entity index, component name ] pairs sorted from highest to lowest
- * Stored as a string but seperated with `__@@ECS@@__`
+ * @prop {number[]} entities
+ * @prop {string[]} components [ entity, component name ]
  */
 /**
  * @typedef { Object } WorldStats
@@ -213,11 +212,11 @@ declare namespace _default {
     export { cleanup };
 }
 export default _default;
-export type ListenerType = 'added' | 'removed';
+export type ListenerType = "added" | "removed";
 export type ListenerResult = Entity[];
 export type Component = any;
 export type Entity = {
-    [key: string]: any;
+    [key: string]: Component;
 };
 export type FilteredEntityList = Entity[];
 export type SystemUpdateFunction = (dt: number) => void;
@@ -229,10 +228,12 @@ export type System = {
     onUpdate?: SystemUpdateFunction;
     onPostUpdate?: SystemUpdateFunction;
 };
-export type SystemFunction = (world: World) => System;
+export type SystemFunction = {
+    (world: World): System;
+};
 export type Listener = any;
 export type ListenerMap = {
-    [key: string]: any;
+    [key: string]: Listener;
 };
 export type ListenerChangeMap = {
     added: ListenerMap;
@@ -242,13 +243,9 @@ export type FilterMap = {
     [filterId: string]: FilteredEntityList;
 };
 export type DeferredRemovalMap = {
-    /**
-     * indexes into entities array, sorted from highest to lowest
-     */
     entities: number[];
     /**
-     * [ entity index, component name ] pairs sorted from highest to lowest
-     * Stored as a string but seperated with `__@@ECS@@__`
+     * [ entity, component name ]
      */
     components: string[];
 };
diff --git a/types/ecs.d.ts.map b/types/ecs.d.ts.map
index 7e4db17..dcbe78c 100644
--- a/types/ecs.d.ts.map
+++ b/types/ecs.d.ts.map
@@ -1 +1 @@
-{"version":3,"file":"ecs.d.ts","sourceRoot":"","sources":["../ecs.js"],"names":[],"mappings":"AAOA;;GAEG;AAEH;;GAEG;AAEH;;GAEG;AAEH;;;;GAIG;AAEH;;GAEG;AAEH;;GAEG;AAEH;;;;;;;;GAQG;AAEH;;;;;GAKG;AAEH;;GAEG;AAEH;;GAEG;AAEH;;;;GAIG;AAEH;;GAEG;AAEH;;;;;GAKG;AAEH;;;;;;;;;;;;;;;GAeG;AAEH;;;;;;;;GAQG;AAEH;;;;;;GAMG;AACH,sCAHW,MAAM,GACJ,KAAK,CAmEjB;AAGD;;;;GAIG;AACH,oCAHW,KAAK,GACH,MAAM,CAclB;AAGD,0DAEC;AAGD,8DAEC;AAGD;;;;;;;GAOG;AACH,4CANW,KAAK,UACL,MAAM,iBACN,MAAM,kBACN,SAAS,GACP,IAAI,CA+BhB;AAGD;;;;;;;GAOG;AACF,iDANU,KAAK,UACL,MAAM,iBACN,MAAM,oBACN,OAAO,GACL,IAAI,CAiBhB;AAGD;;;;;;GAMG;AACF,oCALU,KAAK,UACL,MAAM,oBACN,OAAO,GACL,IAAI,CAmBhB;AAGD;;;;;;;;;;;;;GAaG;AACH,mCAZW,KAAK,kBACL,MAAM,EAAE,iBAKR,YAAY,sCAIV,MAAM,EAAE,CAwCpB;AAGD;;;;;;;;;GASG;AACH,iCARW,KAAK,kBACL,MAAM,EAAE,GAKN,MAAM,GAAC,IAAI,CAIvB;AA8BD;;;;GAIG;AACH,iCAHW,KAAK,MACL,cAAc,QA+BxB;AAED;;;;GAIG;AACH,sCAHW,KAAK,MACL,MAAM,QAUhB;AAGD;;;;GAIG;AACH,mCAHW,KAAK,MACL,MAAM,QAUhB;AAED;;;;GAIG;AACH,uCAHW,KAAK,MACL,MAAM,QAUhB;AAGD;;;;GAIG;AACH,iCAHW,KAAK,MACL,MAAM,QAUhB;AAED;;;;GAIG;AACH,8BAHW,KAAK,MACL,MAAM,QAUhB;AAED;;;;GAIG;AACH,kCAHW,KAAK,MACL,MAAM,QAUhB;AA0HD;;;GAGG;AACH,+BAFW,KAAK,QAyDf;;;;;;;;;;;;;;;;;;;;;2BAxrBa,OAAO,GAAG,SAAS;6BAInB,MAAM,EAAE;wBAIR,GAAG;;;;iCAUH,MAAM,EAAE;wCAIH,MAAM,KAAK,IAAI;;uBAKxB,oBAAoB;oBACpB,oBAAoB;wBACpB,oBAAoB;kBACpB,oBAAoB;eACpB,oBAAoB;mBACpB,oBAAoB;;qCAKjB,KAAK,KAAK,MAAM;;;;;;WAenB,WAAW;aACX,WAAW;;;;;;;;;cASX,MAAM,EAAE;;;;;gBACR,MAAM,EAAE;;;iBAMR,MAAM;;;;;;;;;;;;;;cAIL,MAAM;qBACC,MAAM;;;;;;;;;mBAKd,MAAM;;;;kBAEN,MAAM;;;cAKN,MAAM,EAAE;aACR,SAAS;aACT,MAAM,EAAE;eACR,iBAAiB;sBACjB,kBAAkB;WAClB,UAAU"}
\ No newline at end of file
+{"version":3,"file":"ecs.d.ts","sourceRoot":"","sources":["../ecs.js"],"names":[],"mappings":"AAOA;;GAEG;AAEH;;GAEG;AAEH;;GAEG;AAEH;;;;GAIG;AAEH;;GAEG;AAEH;;GAEG;AAEH;;;;;;;;GAQG;AAEH;;;;;GAKG;AAEH;;GAEG;AAEH;;GAEG;AAEH;;;;GAIG;AAEH;;GAEG;AAEH;;;;GAIG;AAEH;;;;;;;;;;;;;;;GAeG;AAEH;;;;;;;;GAQG;AAEH;;;;;;GAMG;AACH,sCAHW,MAAM,GACJ,KAAK,CAmEjB;AAGD;;;;GAIG;AACH,oCAHW,KAAK,GACH,MAAM,CAclB;AAGD,0DAEC;AAGD,8DAEC;AAGD;;;;;;;GAOG;AACH,4CANW,KAAK,UACL,MAAM,iBACN,MAAM,kBACN,SAAS,GACP,IAAI,CA+BhB;AAGD;;;;;;;GAOG;AACF,iDANU,KAAK,UACL,MAAM,iBACN,MAAM,oBACN,OAAO,GACL,IAAI,CAchB;AAGD;;;;;;GAMG;AACF,oCALU,KAAK,UACL,MAAM,oBACN,OAAO,GACL,IAAI,CAkBhB;AAGD;;;;;;;;;;;;;GAaG;AACH,mCAZW,KAAK,kBACL,MAAM,EAAE,iBAKR,YAAY,qBAEV,cAAc,GAEd,MAAM,EAAE,CAwCpB;AAGD;;;;;;;;;GASG;AACH,iCARW,KAAK,kBACL,MAAM,EAAE,GAKN,MAAM,GAAC,IAAI,CAIvB;AA8BD;;;;GAIG;AACH,iCAHW,KAAK,MACL,cAAc,QA+BxB;AAED;;;;GAIG;AACH,sCAHW,KAAK,MACL,MAAM,QAUhB;AAGD;;;;GAIG;AACH,mCAHW,KAAK,MACL,MAAM,QAUhB;AAED;;;;GAIG;AACH,uCAHW,KAAK,MACL,MAAM,QAUhB;AAGD;;;;GAIG;AACH,iCAHW,KAAK,MACL,MAAM,QAUhB;AAED;;;;GAIG;AACH,8BAHW,KAAK,MACL,MAAM,QAUhB;AAED;;;;GAIG;AACH,kCAHW,KAAK,MACL,MAAM,QAUhB;AA2GD;;;GAGG;AACH,+BAFW,KAAK,QAkDf;;;;;;;;;;;;;;;;;;;;;2BA7pBa,OAAO,GAAG,SAAS;6BAInB,MAAM,EAAE;wBAIR,GAAG;qBAIJ;IACZ,CAAK,GAAG,EAAE,MAAM,GAAI,SAAS,CAAA;CAC1B;iCAIU,MAAM,EAAE;mCAIR,CAAC,EAAE,EAAE,MAAM,KAAK,IAAI;;uBAKxB,oBAAoB;oBACpB,oBAAoB;wBACpB,oBAAoB;kBACpB,oBAAoB;eACpB,oBAAoB;mBACpB,oBAAoB;;6BAIjB;IACZ,CAAK,KAAK,EAAE,KAAK,GAAK,MAAM,CAAA;CACzB;;0BASS;IAAE,CAAE,GAAG,EAAE,MAAM,GAAI,QAAQ,CAAA;CAAE;;WAKhC,WAAW;aACX,WAAW;;wBAIR;IAAE,CAAE,QAAQ,EAAE,MAAM,GAAI,kBAAkB,CAAA;CAAE;;cAK/C,MAAM,EAAE;;;;gBACR,MAAM,EAAE;;;iBAKR,MAAM;;;;oBACN;QAAE,CAAE,GAAG,EAAE,MAAM,GAAI,MAAM,CAAA;KAAE;;;;2BAC3B;QAAE,CAAE,GAAG,EAAE,MAAM,GAAI,MAAM,CAAA;KAAE;aAC3B;QACT,IAAQ,EAAE,MAAM,CAAC;QACjB,WAAe,EAAE,MAAM,CAAC;QACxB,OAAW,EAAE;YACb,CAAQ,GAAG,EAAE,MAAM,GAAI,MAAM,CAAC;SACzB,CAAC;KACH,EAAE;;;;;mBACI,MAAM;;;;kBAEN,MAAM;;;cAKN,MAAM,EAAE;aACR,SAAS;aACT,MAAM,EAAE;eACR,iBAAiB;sBACjB,kBAAkB;WAClB,UAAU"}
\ No newline at end of file