Yes! I want to build this and SortedSet.

+100

Just figured out I need this.

+1 from me.

+1 indeed

👍

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Sorted map would be great! 👍

Also, an OrderedMap can be implemented atop of a SortedMap without amortization.

That would be so useful!

Agreed. If I understand correctly .sort() creates a copy every time (even when called in withMutations). So if I want to insert sorted, I have to duplicate the OrderedMap twice. eg:

const map = OrdererMap({a: 'a', c: 'c'});
const sorted = map.set('b', 'b').sort(); // Creates two copies.

For prior art on this issue, Clojure(script)'s sorted-map implementation uses a persistent red-black tree:

• Java: https://github.com/clojure/clojure/blob/010864f8ed828f8d261807b7345f1a539c5b20df/src/jvm/clojure/lang/PersistentTreeMap.java
• Clojure (used in Clojurescript): https://github.com/clojure/clojurescript/blob/609400910e983849e5b7932a4b7d0b0dda465df6/src/main/cljs/cljs/core.cljs#L7066

There's a JavaScript implementation of the same data structure here that might be useful, too.

Clojure's sorted-set uses the same data structure, slightly wrapped: https://github.com/clojure/clojure/blob/clojure-1.7.0/src/jvm/clojure/lang/PersistentTreeSet.java

RB Tree sounds like the right way to do this.

I'm putting this up for grabs for any adventurous contributors. Best way to learn about Persistent Immutable data structures is to implement them!

Have not used yet but this SortedMap seems promising.

@akagomez Want to take a crack at RB Tree implementation?

Tempting @crodriguez1a.

I've done a bunch of work with Red-Black Binary Tree's for CanJS (https://github.com/canjs/can-binarytree), based on a fork of this repo: https://github.com/vadimg/js_bintrees

Leveraging that RB Tree implementation again should make this a less daunting task.

If nobody disagrees with this approach I don't mind taking a crack at it with @crodriguez1a's help.

@akagomez feel free to steal from my toy SortedMap (api not fully implemented) that I started for a side project: https://github.com/rongierlach/immutable-sorted-map/

It is using a regular BST under the hood, am intending to convert it to RB later on.

The long wait is over. Have a look at our immutable-js fork with highly optimized implementation of SortedMap and SortedSet. Current version is using classic B-trees. https://github.com/applitopia/immutable-sorted

Darn, I was looking forward to playing with this myself.

Maybe @crodriguez1a and I can help convert @applitopia's implementation to use RB-trees.

@applitopia - please consider contributing those implementations to this project!

For reference if you want to adapt it, or as an alternative solution, my own immutable collections library has (among others) a sorted map, a sorted set and a red-black tree. The sorted map/set collections behave like Immutable.js' ordered equivalents by default, or you can supply a custom sorting predicate to have them sort their elements however you like. https://github.com/frptools/collectable

Need this too! Thanks