feat(memoize): add doOnce(), update readme

packages/memoize/README.md

@@ -54,7 +54,7 @@ yarn add @thi.ng/memoize
 <script src="https://unpkg.com/@thi.ng/memoize/lib/index.umd.js" crossorigin></script>
 ```
 
-Package sizes (gzipped, pre-treeshake): ESM: 254 bytes / CJS: 305 bytes / UMD: 389 bytes
+Package sizes (gzipped, pre-treeshake): ESM: 282 bytes / CJS: 336 bytes / UMD: 417 bytes
 
 ## Dependencies
 

packages/memoize/src/do-once.ts

@@ -0,0 +1,19 @@
+import type { Fn } from "@thi.ng/api";
+import { MapLike } from "./api";
+
+/**
+ * Similar to {@link memoize1}, however optimized for side effects only, i.e.
+ * functions which DO NOT return any result.
+ *
+ * @param fn
+ * @param cache
+ */
+export const doOnce = <T>(fn: Fn<T, void>, cache?: MapLike<T, boolean>) => {
+    !cache && (cache = new Map());
+    return (x: T) => {
+        if (!cache!.has(x)) {
+            cache!.set(x, true);
+            fn(x);
+        }
+    };
+};

packages/memoize/src/index.ts

@@ -1,5 +1,6 @@
 export * from "./api";
 export * from "./defonce";
+export * from "./do-once";
 export * from "./memoize";
 export * from "./memoize1";
 export * from "./memoizej";

packages/memoize/src/memoize1.ts

@@ -13,12 +13,12 @@ import type { MapLike } from "./api";
  * @param fn -
  * @param cache -
  */
-export function memoize1<A, B>(fn: Fn<A, B>, cache?: MapLike<A, B>) {
+export const memoize1 = <A, B>(fn: Fn<A, B>, cache?: MapLike<A, B>) => {
     !cache && (cache = new Map());
     return (x: A): B => {
         let res;
         return cache!.has(x)
             ? cache!.get(x)!
             : (cache!.set(x, (res = fn(x))), res);
     };
-}
+};