Move update method from Map to Iterable

src/Iterable.ts

@@ -4,6 +4,7 @@ import {
   Reducer,
   Option,
   Transform,
+  Updater,
   Dict
 } from './constants'
 
@@ -48,6 +49,11 @@ abstract class Iterable<K, T> {
     return !this.size
   }
 
+  update(key: K, updater: Updater<T>): Iterable<K, T> {
+    const value = this.get(key) as T
+    return this.set(key, updater(value))
+  }
+
   forEach(sideEffect: (value: T, key: K) => void) {
     this.__iterate((value: T, key: K) => {
       sideEffect(value, key)

src/Map.ts

@@ -1,4 +1,4 @@
-import { Predicate, Transform, Updater, Option } from './constants'
+import { Predicate, Transform, Option } from './constants'
 import hash from './util/hash'
 import BitmapIndexedNode, { emptyNode } from './kvHamt/BitmapIndexedNode'
 import Iterable from './Iterable'
@@ -85,11 +85,6 @@ export default class Map<K, T> extends Iterable<K, T> {
     return makeMap<K, T>(root)
   }
 
-  update(key: K, updater: Updater<T>): Iterable<K, T> {
-    const value = this.get(key) as T
-    return this.set(key, updater(value))
-  }
-
   map<G>(transform: Transform<K, T, G>): Map<K, G> {
     const root = this.root.map<G>(transform, this.owner) as BitmapIndexedNode<K, G>
     if (this.owner) {