[Functional Programming ADT] Combine Multiple State ADT Based Redux Reducers
Redux provides a convenient helper for combining many reducers called combineReducer
, but it focuses in on specific attributes on our state, making it incompatible with using the State ADT. We would like a way to avoid keeping all of our reducers in a single file and want the ability to still combine them in a manner that works with the State
ADT.
So we will put together our own helper that we also call combineReducers
, but explore how we can use the First
Monoid and mreduceMap
to get us all the power that the Redux helper provides, but setup for our unique needs. As a bonus we will get a sneak peak of the power of using the flip
combinator to create easy to read compositions without pesky argument juggling
// combineReducers :: [ Reducer ] -> Reducer
/*
export const combineReducers = reducers => action =>
mreduceMap(First, applyTo(action), reducers);
*/
// We take reducers first and action second, but we use action first, reducers second.
// It is good case to use flip
/*
export const combineReducers = flip(action =>
mreduceMap(First, applyTo(action))
);*/ // We can use compose to remove action param, applyTo will get action
// Then the return result will be passed into mreduceMap(First)
export const combineReducers = flip(
compose(
mreduceMap(First),
applyTo
)
);
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