10 ms·

Learn Functional Programming Design from Redux

58 points by daiyanze 6y ago

acemarke 6y ago
Side note: I just published a brand-new "Redux Essentials" core docs tutorial. It teaches beginners "how to use Redux, the right way", using our latest recommended tools and practices, including Redux Toolkit for writing your Redux code, the React-Redux hooks API for interacting with Redux in your components, and use of single-file "slices" for a given feature's Redux logic. I'd encourage folks to check it out: https://redux.js.org/tutorials/essentials/part-1-overview-concepts https://redux.js.org/tutorials/essentials/part-1-overview-co... My next step will be to rewrite the existing "bottom-up" tutorial sequence to simplify explanations, remove outdated references, improve the explanation flow, and add more running examples.
- lf-non 6y ago
  I'd recommend caution when adopting redux-toolkit in large & rapidly-evolving projects. I recently (2 months back) moved a medium sized project (~240 branch reducers, ~600 actions) away from redux-toolkit. My primary complaint is that the recommended setup doesn't work well with changing requirements where we often have to move away from branch-local state handling to something that needs access to wider state. We started out with a number of slices and our reducer logic was local to these slices and used only the state within that slice. However as our application evolved, for processing a number of these actions (which were previously slice-local) we needed access to state from other branches. So now we had a couple of options: A. Dispatch thunks instead of actions: This gets ugly real fast because now your action handling logic is split across thunks & reducers, and is hard to follow. This also needs refactoring across every dispatch site. B. Use something like redux sagas to intercept actions: We found this to be "too" flexible and felt that we were better-off without the entire machinery of spawning sagas on the fly. We wanted it to be easy to reason about what happens when an action is dispatched looking at the code without having to debug what all sagas could be running at that particular point of time. C. Move the action handling higher up: requires extensively refactoring the reducers. The solution we settled on was redux-loop [1]: A port of elm's effect system to redux. This was neat because we could easily convert the reducer to return loops instead of states, and thereby easily get access to full state and dispatch while retaining the ability to follow through the complete action handling flow from a single starting point that didn't change. TypeScript support in redux-toolkit is also kind'a bolted on and users are recommended different approaches when they care about type-safety. It proved to be a pain to communicate junior devs multiple times that you should use leave the reducers as empty object and instead use "extraReducers" with builder API. We found using immer[2] (for managing immutable state) and unionize[3] (for handling discriminated union of action types) directly to be a much better solution than redux-toolkit's abstractions. [1]: https://github.com/redux-loop/redux-loop https://github.com/redux-loop/redux-loop [2]: https://github.com/immerjs/immer https://github.com/immerjs/immer [3]: https://www.npmjs.com/package/unionize https://www.npmjs.com/package/unionize
  - acemarke 6y ago
    RTK doesn't change anything about how you write reducers and actions that need to interact across slices. Our recommendations have always been the same: reorganize slice reducers so they handle more state, put more data in actions, or coordinate via side effects [0]. The only thing that changes with RTK is that we now recommend using the single-file "slice/ducks" pattern for a given feature's Redux logic, and RTK's `createSlice` API makes it easier to write code that's organized that way. If you do have cross-slice dependencies, where slice A and B both want to respond to each other's actions, that _could_ potentially lead to cyclic dependency issues. Our RTK Usage Guide page specifically addresses that question [1], and resolving it is generally a matter of defining the relevant actions in a separate file again. But, having logic in a single file by default drastically simplifies things in most cases. This issue isn't unique to RTK - it exists any time you're trying to have different slices depend on each other, regardless of how the logic in those files are implemented. Also strongly disagree that RTK's TS support is "bolted on". RTK is written in TS, and we've spent hundreds of hours trying to ensure our APIs work well with TS [2]. We test against multiple TS versions, design our APIs to minimize the amount of types you have to declare, and try to offer the best type safety possible with our preferred API structure. The only time you would ever define `createSlice.extraReducers` as an empty object is if you are _only_ using that slice as a data cache and not adding any additional client-side logic that would manipulate that cached data. In that case, you'd probably be better suited to use `createReducer` directly. Having said that, we are currently working on a PR to add the ability to declare async thunks directly inside of `createSlice` [3], leveraging our new `createAsyncThunk` API [4] so that their action types are automatically generated to match the slice name and the action creator name you specify. That will eliminate the need to call `createAsyncThunk` separately and pass its actions to `createSlice.extraReducers`. Finally, RTK has been built around Immer since day 1, and it's used in `createReducer` and `createSlice` to allow you to write simpler "mutating" immutable update logic. If you have any additional specific concerns, please ping me on Twitter or in the Reactiflux Discord. I'm always happy to answer questions and offer suggestions, and I would really be interested in seeing some details on the app you're working on to see if there's any ideas for improving RTK's APIs for your kind of use case. [0] https://redux.js.org/faq/reducers#how-do-i-share-state-between-two-reducers-do-i-have-to-use-combinereducers https://redux.js.org/faq/reducers#how-do-i-share-state-betwe... [1] https://redux-toolkit.js.org/usage/usage-guide#exporting-and-using-slices https://redux-toolkit.js.org/usage/usage-guide#exporting-and... [2] https://github.com/reduxjs/redux-toolkit/pull/393 https://github.com/reduxjs/redux-toolkit/pull/393 [3] https://github.com/reduxjs/redux-toolkit/pull/637 https://github.com/reduxjs/redux-toolkit/pull/637 [4] https://redux-toolkit.js.org/api/createAsyncThunk https://redux-toolkit.js.org/api/createAsyncThunk
yakshaving_jgt 6y ago
In my experience learning, teaching, and watching other people learn FP, it's far easier to learn FP with a language which is actually designed for it, e.g., Elm. JavaScript isn't that. It carries too much legacy baggage. Too many gotchas; too many pointy bits. It's also just super noisy. There's a reason why someone had to write The Good Parts. I don't buy the idea either that modern JavaScript is somehow devoid of the kinds of problems that existed when Crockford wrote that book. I mean, how many people still think that `const` gives you an immutable value? n.b. I'm not sure why the Haskell snippet was included. It's confusing, and doesn't even make sense given that `main` is defined twice.
- Osiris 6y ago
  This is my experience as well. I had a co-worker that really pushed for FP in JavScript using Ramda.js. the principles were appealing, but because JavaScript doesn't have native syntax for many of the principles like pattern matching, you end up with hard to read code that's a bunch of nested arrays or chains wrapped in helper functions like "compose([fn1, fn2])(data)". I later tried to learn F# and while the syntax was foreign, it turned out that it was MUCH easier to write FP code because the language had native operators for composition, etc. The code was also much easier to read. I think it would be great if JavaScript got some FP syntax natively (see the pattern matching proposal). But hacking functional principals using arrays and helper functions just leads to hard to read code, especially for people not familiar with the specific FP library you chose to use.
  - adamkl 6y ago
    I'm actually thinking about putting together a series of posts on the topic of "Full-stack ClojureScript for JavaScript developers". I've heard ClojureScript described (from a functional programming standpoint) as "JavaScript, but without the stupid parts", as it basically gives you the benefits of Ramda.js + Immutable.js without the headaches of making those libraries play nicely with native JavaScript. It also doesn't veer too far into the theoretical (monads, category theory, etc) so it would make for an easier transition when coming from JavaScript (you can even throw exceptions if you want). I became a Clojure fan-boy over the course of the last year but one issue that seems to keep popping up when I discuss it with my JavaScript/Node.js co-workers is "Clojure runs on the JVM? Not interested". Setting aside the technical validity of that opinion (JVM vs. Node.js), it made me wonder if there might be more interest in Clojure from the JavaScript world if they knew they could use ClojureScript for both the front-end and the back-end (on Node.js).
hasperdi 6y ago
IMO Redux is a terrible way to start learning functional programming. There is too much boilerplate code and other code (ie. reducer, selectors, side effects, react components) that will confuse beginners and make the goal of learning functional programming harder. It's like telling someone who wants to learn to drive, here's the road laws book, car manual, car service manual, offroad rally driving guide and engine tuning manual.
- Zealotux 6y ago
  Redux was my first introduction to FP, and I loved it. You simply have to use Redux Toolkit that takes care of the ugly parts of Redux (namely: the boilerplate code), and it becomes a breeze to build things with Redux.
- ummonk 6y ago
  Yup. Just use hooks.
wqsz7xn 6y ago
main :: (RealWorld ->) ((), RealWorld) I've been doing haskell for a few months now. I don't think I have ever seen a expression like this. It looks like State. Is this even valid syntactically? I'm Probably bikeshedding.
- yakshaving_jgt 6y ago
  The Haskell snippet included is basically gibberish. It’s best to ignore it.
  - tome 6y ago
    Has it been removed? I don't see any Haskell in the article.
    - yakshaving_jgt 6y ago
      Looks like it has been removed, yes.
      - yakshaving_jgt 6y ago
        Actually no it hasn't. I think I'm just blind occasionally.
    - dddbbb 6y ago
      It's still there as far as I can see, it's in an image[0]. I believe their intention is to show a kind of pseudo-desugaring of what the IO monad actually does internally. [0] -- https://pitayan.com/assets/static/haskell.cbab2cf.82d9f5b0912290333a547a32e17d3642.jpg https://pitayan.com/assets/static/haskell.cbab2cf.82d9f5b091...
      - tome 6y ago
        Ah yes, just goes to show I ignore images in articles!
diegof79 6y ago
While I use Redux, and I like the simplicity of the single application state and the reducer function. I don't see it as a good example of FP or even JavaScript. The problem with Redux is that it takes many patterns that make sense in languages like Haskell or Elm but are not idiomatic in JS. For example, action types and the usual reducer switch statement is easier to write and extend in Haskell. And is not idiomatic JavaScript either. It always baffles me that an action dispatch is a way of doing a method dispatch (and yes I know that unlike a method dispatch an action can be persisted, and broadcasted). But if you compare the boilerplate and concepts introduced by a simple action dispatch (action creator, action type, payload, thunk, middleware) with a simple method call, and you look at the benefits (late binding with the state, persistence)... I wonder why solutions like Zustand didn't come up before. (note, I wrote state management code similar to Zustand for my personal projects, but one of the reasons to continue using Redux is that getting the Context updates right is hard... a problem solved by React-Redux with addition of nice tooling and collaboration from core React devs. As soon React adds fine-grained context state updates the reasons to continue using Redux for me are low).

58 points by daiyanze 6y ago

Side note: I just published a brand-new "Redux Essentials" core docs tutorial. It teaches beginners "how to use Redux, the right way", using our latest recommended tools and practices, including Redux Toolkit for writing your Redux code, the React-Redux hooks API for interacting with Redux in your components, and use of single-file "slices" for a given feature's Redux logic. I'd encourage folks to check it out: https://redux.js.org/tutorials/essentials/part-1-overview-concepts https://redux.js.org/tutorials/essentials/part-1-overview-co... My next step will be to rewrite the existing "bottom-up" tutorial sequence to simplify explanations, remove outdated references, improve the explanation flow, and add more running examples.

lf-non 6y ago
I'd recommend caution when adopting redux-toolkit in large & rapidly-evolving projects. I recently (2 months back) moved a medium sized project (~240 branch reducers, ~600 actions) away from redux-toolkit. My primary complaint is that the recommended setup doesn't work well with changing requirements where we often have to move away from branch-local state handling to something that needs access to wider state. We started out with a number of slices and our reducer logic was local to these slices and used only the state within that slice. However as our application evolved, for processing a number of these actions (which were previously slice-local) we needed access to state from other branches. So now we had a couple of options: A. Dispatch thunks instead of actions: This gets ugly real fast because now your action handling logic is split across thunks & reducers, and is hard to follow. This also needs refactoring across every dispatch site. B. Use something like redux sagas to intercept actions: We found this to be "too" flexible and felt that we were better-off without the entire machinery of spawning sagas on the fly. We wanted it to be easy to reason about what happens when an action is dispatched looking at the code without having to debug what all sagas could be running at that particular point of time. C. Move the action handling higher up: requires extensively refactoring the reducers. The solution we settled on was redux-loop [1]: A port of elm's effect system to redux. This was neat because we could easily convert the reducer to return loops instead of states, and thereby easily get access to full state and dispatch while retaining the ability to follow through the complete action handling flow from a single starting point that didn't change. TypeScript support in redux-toolkit is also kind'a bolted on and users are recommended different approaches when they care about type-safety. It proved to be a pain to communicate junior devs multiple times that you should use leave the reducers as empty object and instead use "extraReducers" with builder API. We found using immer[2] (for managing immutable state) and unionize[3] (for handling discriminated union of action types) directly to be a much better solution than redux-toolkit's abstractions. [1]: https://github.com/redux-loop/redux-loop https://github.com/redux-loop/redux-loop [2]: https://github.com/immerjs/immer https://github.com/immerjs/immer [3]: https://www.npmjs.com/package/unionize https://www.npmjs.com/package/unionize
- acemarke 6y ago
  RTK doesn't change anything about how you write reducers and actions that need to interact across slices. Our recommendations have always been the same: reorganize slice reducers so they handle more state, put more data in actions, or coordinate via side effects [0]. The only thing that changes with RTK is that we now recommend using the single-file "slice/ducks" pattern for a given feature's Redux logic, and RTK's `createSlice` API makes it easier to write code that's organized that way. If you do have cross-slice dependencies, where slice A and B both want to respond to each other's actions, that _could_ potentially lead to cyclic dependency issues. Our RTK Usage Guide page specifically addresses that question [1], and resolving it is generally a matter of defining the relevant actions in a separate file again. But, having logic in a single file by default drastically simplifies things in most cases. This issue isn't unique to RTK - it exists any time you're trying to have different slices depend on each other, regardless of how the logic in those files are implemented. Also strongly disagree that RTK's TS support is "bolted on". RTK is written in TS, and we've spent hundreds of hours trying to ensure our APIs work well with TS [2]. We test against multiple TS versions, design our APIs to minimize the amount of types you have to declare, and try to offer the best type safety possible with our preferred API structure. The only time you would ever define `createSlice.extraReducers` as an empty object is if you are _only_ using that slice as a data cache and not adding any additional client-side logic that would manipulate that cached data. In that case, you'd probably be better suited to use `createReducer` directly. Having said that, we are currently working on a PR to add the ability to declare async thunks directly inside of `createSlice` [3], leveraging our new `createAsyncThunk` API [4] so that their action types are automatically generated to match the slice name and the action creator name you specify. That will eliminate the need to call `createAsyncThunk` separately and pass its actions to `createSlice.extraReducers`. Finally, RTK has been built around Immer since day 1, and it's used in `createReducer` and `createSlice` to allow you to write simpler "mutating" immutable update logic. If you have any additional specific concerns, please ping me on Twitter or in the Reactiflux Discord. I'm always happy to answer questions and offer suggestions, and I would really be interested in seeing some details on the app you're working on to see if there's any ideas for improving RTK's APIs for your kind of use case. [0] https://redux.js.org/faq/reducers#how-do-i-share-state-between-two-reducers-do-i-have-to-use-combinereducers https://redux.js.org/faq/reducers#how-do-i-share-state-betwe... [1] https://redux-toolkit.js.org/usage/usage-guide#exporting-and-using-slices https://redux-toolkit.js.org/usage/usage-guide#exporting-and... [2] https://github.com/reduxjs/redux-toolkit/pull/393 https://github.com/reduxjs/redux-toolkit/pull/393 [3] https://github.com/reduxjs/redux-toolkit/pull/637 https://github.com/reduxjs/redux-toolkit/pull/637 [4] https://redux-toolkit.js.org/api/createAsyncThunk https://redux-toolkit.js.org/api/createAsyncThunk

yakshaving_jgt 6y ago

In my experience learning, teaching, and watching other people learn FP, it's far easier to learn FP with a language which is actually designed for it, e.g., Elm. JavaScript isn't that. It carries too much legacy baggage. Too many gotchas; too many pointy bits. It's also just super noisy. There's a reason why someone had to write The Good Parts. I don't buy the idea either that modern JavaScript is somehow devoid of the kinds of problems that existed when Crockford wrote that book. I mean, how many people still think that `const` gives you an immutable value? n.b. I'm not sure why the Haskell snippet was included. It's confusing, and doesn't even make sense given that `main` is defined twice.

Osiris 6y ago
This is my experience as well. I had a co-worker that really pushed for FP in JavScript using Ramda.js. the principles were appealing, but because JavaScript doesn't have native syntax for many of the principles like pattern matching, you end up with hard to read code that's a bunch of nested arrays or chains wrapped in helper functions like "compose([fn1, fn2])(data)". I later tried to learn F# and while the syntax was foreign, it turned out that it was MUCH easier to write FP code because the language had native operators for composition, etc. The code was also much easier to read. I think it would be great if JavaScript got some FP syntax natively (see the pattern matching proposal). But hacking functional principals using arrays and helper functions just leads to hard to read code, especially for people not familiar with the specific FP library you chose to use.
- adamkl 6y ago
  I'm actually thinking about putting together a series of posts on the topic of "Full-stack ClojureScript for JavaScript developers". I've heard ClojureScript described (from a functional programming standpoint) as "JavaScript, but without the stupid parts", as it basically gives you the benefits of Ramda.js + Immutable.js without the headaches of making those libraries play nicely with native JavaScript. It also doesn't veer too far into the theoretical (monads, category theory, etc) so it would make for an easier transition when coming from JavaScript (you can even throw exceptions if you want). I became a Clojure fan-boy over the course of the last year but one issue that seems to keep popping up when I discuss it with my JavaScript/Node.js co-workers is "Clojure runs on the JVM? Not interested". Setting aside the technical validity of that opinion (JVM vs. Node.js), it made me wonder if there might be more interest in Clojure from the JavaScript world if they knew they could use ClojureScript for both the front-end and the back-end (on Node.js).

hasperdi 6y ago

IMO Redux is a terrible way to start learning functional programming. There is too much boilerplate code and other code (ie. reducer, selectors, side effects, react components) that will confuse beginners and make the goal of learning functional programming harder. It's like telling someone who wants to learn to drive, here's the road laws book, car manual, car service manual, offroad rally driving guide and engine tuning manual.

Zealotux 6y ago
Redux was my first introduction to FP, and I loved it. You simply have to use Redux Toolkit that takes care of the ugly parts of Redux (namely: the boilerplate code), and it becomes a breeze to build things with Redux.
ummonk 6y ago
Yup. Just use hooks.

wqsz7xn 6y ago

main :: (RealWorld ->) ((), RealWorld) I've been doing haskell for a few months now. I don't think I have ever seen a expression like this. It looks like State. Is this even valid syntactically? I'm Probably bikeshedding.

yakshaving_jgt 6y ago
The Haskell snippet included is basically gibberish. It’s best to ignore it.
- tome 6y ago
  Has it been removed? I don't see any Haskell in the article.
  - yakshaving_jgt 6y ago
    Looks like it has been removed, yes.
    - yakshaving_jgt 6y ago
      Actually no it hasn't. I think I'm just blind occasionally.
  - dddbbb 6y ago
    It's still there as far as I can see, it's in an image[0]. I believe their intention is to show a kind of pseudo-desugaring of what the IO monad actually does internally. [0] -- https://pitayan.com/assets/static/haskell.cbab2cf.82d9f5b0912290333a547a32e17d3642.jpg https://pitayan.com/assets/static/haskell.cbab2cf.82d9f5b091...
    - tome 6y ago
      Ah yes, just goes to show I ignore images in articles!

diegof79 6y ago

While I use Redux, and I like the simplicity of the single application state and the reducer function. I don't see it as a good example of FP or even JavaScript. The problem with Redux is that it takes many patterns that make sense in languages like Haskell or Elm but are not idiomatic in JS. For example, action types and the usual reducer switch statement is easier to write and extend in Haskell. And is not idiomatic JavaScript either. It always baffles me that an action dispatch is a way of doing a method dispatch (and yes I know that unlike a method dispatch an action can be persisted, and broadcasted). But if you compare the boilerplate and concepts introduced by a simple action dispatch (action creator, action type, payload, thunk, middleware) with a simple method call, and you look at the benefits (late binding with the state, persistence)... I wonder why solutions like Zustand didn't come up before. (note, I wrote state management code similar to Zustand for my personal projects, but one of the reasons to continue using Redux is that getting the Context updates right is hard... a problem solved by React-Redux with addition of nice tooling and collaboration from core React devs. As soon React adds fine-grained context state updates the reasons to continue using Redux for me are low).