Specify initial value of reducer

[klimashkin]

Hello!

Sorry if it's been discussed or documented, but I could not find solution.
How to specify initial value of reducer in case of currying?

If on first @@redux/INIT run I don't do anything with draft, redux complains about returned undefined during initialization. If the state passed to the reducer is undefined, you must explicitly return the initial state.. But if I do

some: produce((draft, action) => {
    if (draft === undefined) {
      return {};
    }
}

redux throw the same error...
Using version 1.1.0, and I though that returning object from producers should already work, strange.

[mweststrate]

Hi Paul, could you set up a minimal reproduction in a codesandbox? Op wo 21 feb. 2018 om 09:24 schreef Paul Klimashkin < notifications@github.com>:

…

Hello! Sorry if it's been discussed or documented, but I could not find solution. How to specify initial value of reducer in case of currying? If on first @@redux/INIT run I don't do anything with draft, redux complains about returned undefined during initialization. If the state passed to the reducer is undefined, you must explicitly return the initial state.. But if I do some: produce((draft, action) => { if (draft === undefined) { return {}; } } redux throw the same error... Using version 1.1.0, and I though that returning object from producers should already work, strange. — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub <#105>, or mute the thread <https://github.com/notifications/unsubscribe-auth/ABvGhA4PtdZ-y8N5KSdx9G3nKWh_Urcuks5tW9KlgaJpZM4SNO6w> .

[klimashkin]

Created simple pen where returning from currying doesn't work:
https://codesandbox.io/s/yq7q3y857v

I found in the doc:

One think to keep in mind; you cannot use this construction to initialize an uninitialized state. E.g. draft = {} doesn't do anything useful.

Seems like the only way is to pass initial value on store startup, but it's not convenient in redux world.
What if initial value could be passed as second parameter to curry function like for array.reduce?
Like

const counter = produce((draft, action) => {  
  switch (action.type) {
    case 'INCREMENT':
      return draft.count += 1;
    case 'DECREMENT':
      return draft.count -= 1;
  }
}, {count: 0});

[mweststrate]

@klimashkin apologies, this was a bug in the currying! Should be fixed in 1.1.1

[mweststrate]

See: https://codesandbox.io/s/j4m8q25363

[klimashkin]

Thanks @mweststrate!

What do you think about setting default value as a second parameter of curried produce? In redux we have to have default value for every reducer, writing if (draft === undefined) seems a little verbose

[mweststrate]

@klimashkin could you open a separate issue for that?