Add more immutability helpers.

[Gonzih]

Hello, I like Idea of immutability helpers in react, but I find them incomplete. I still from time to time switch to Underscore for complex operations on data. Does it make sense to add more helpers like:

• $map
• $filter
• $fold
• set like operations (union/difference/intersection), of course they can be implemented in terms of fold.

What do you think guys? Thanks.

[syranide]

Personally, I run with much simplified helper instead, that only supports the equivalent of $apply. That allows me to work with immutable data as if it was mutable, with the regular functions for mutating.

Something like: (immutate simply shallow clones)

var nextObj = immutate(prevObj, {
  user: function(obj) {
    obj.name = 'Test';
    obj.permissions = immutate(obj.permissions, function(arr) {
      arr.push(1);
      arr.push(2);
    });
  },
});

[Gonzih]

How immutate implementation looks like?

[syranide]

https://gist.github.com/syranide/d75f32ebad237112d324
I haven't really vetted it yet, but it should work fine.

nextObject = immutate(prevObject, keysToMutateOrMutator);

var prev = {value: 1, permissions: { ids: [1,2,3] }};

var next = immutate(prev, function(user) {
  user.name = 'next';
  user.permissions = immutate(obj.permissions, { ids: function(ids) {
    ids.push(4, 5);
    ids.shift();
  }});
});

prev before: {"name":"previous","permissions":{"ids":[1,2,3]}}
prev after:  {"name":"previous","permissions":{"ids":[1,2,3]}}
next after:  {"name":"next","permissions":{"ids":[2,3,4,5]}}

I've also thought about getting rid of the redundancy when mutating by providing a second argument to the callback, that could look like: function(user, mutate) { mutate({permissions: {ids: ... }}); } but haven't thought that much about it just yet.

PS. As always, use at your own risk :)

[Gonzih]

Well I still would love to have more complete helpers in react. If I need rich api for immutable data operations I can of course adopt Underscore for that or integrate Mori in to react. Question then is why you need helpers in react if they are incomplete?

[sophiebits]

var next = {
  ...prev,
  name: 'next',
  permissions: {
    ...,
    ids: prev.permissions.ids.slice(1).concat([4, 5])
  }
};

[syranide]

@spicyj Oooh, very interesting use of the spread operator (or whatever it is called).

[jardakotesovec]

For removing element from array I can use $splice, but how I could remove property from object using immutable helpers? Just want to remove particular key.

[chenglou]

@jardakotesovec #2362

@Gonzih: immutable-js is a fully featured immutable collection library that provides the helpers you want and more. Since update is getting deprecated/pulled out into its own repo, we can always come back to this after that.

@petehunt can we close this now?

[gaearon]

As far as I know the current thinking is that React.addons.update is in maintenance mode and will not get new features. We encourage people to look at Immutable.js or alternative libraries that deal with plain objects instead.