@@ -4,13 +4,13 @@ A Lens type for [Effect](https://effect.website/) to easily manage nested state.
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## Install
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```
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npm install effect-lens@beta effect@4.0.0-beta.85
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yarn add effect-lens@beta effect@4.0.0-beta.85
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bun add effect-lens@beta effect@4.0.0-beta.85
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npm install effect-lens@beta effect@4.0.0-beta.98
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yarn add effect-lens@beta effect@4.0.0-beta.98
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bun add effect-lens@beta effect@4.0.0-beta.98
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```
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## Peer dependencies
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- `effect` 4.0.0-beta.85
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- `effect` 4.0.0-beta.98
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## Quickstart
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@@ -64,7 +64,7 @@ You can also create Lenses manually using `make` by providing:
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- `get`: an effect that reads the current value,
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- `changes`: a stream of value changes,
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- `commit`: an effectful write primitive,
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- `lock`: an effect that produces the lock used to serialize writes.
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- `lock`: an effect that produces the lock used to serialize writes and preserve atomicity.
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You can get pretty creative! Here's an example of a Lens that points to a specific key of the browser `LocalStorage`:
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```typescript
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@@ -101,9 +101,6 @@ const lens = Effect.all([
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)
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```
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Note: while Lens supports asynchronous effects for the proxy logic, we would recommend keeping them synchronous to preserve atomicity.
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### Focusing
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Lenses can focus on a nested part of the data type they point to.
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@@ -242,30 +239,33 @@ const nameLens = lens.pipe(
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### View
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Effect 4 no longer provides its former `Subscribable` and `Readable` abstractions. This library provides a `View` interface, which you can use as a constraint to allow some parts of your app to only read and subscribe to the Lenses you provide them:
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A `View` is a read-only, reactive view of a value: it lets you read the current value and observe subsequent changes. Every `Lens` is also a `View`, which you can use as a constraint to allow some parts of your app to only read and subscribe to the Lenses you provide them. It replaces Effect v3's `Subscribable` module:
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```typescript
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const ref = yield* SubscriptionRef.make<{
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readonly users: readonly User[]
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}>({ users: [...] })
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}>({ users: [] })
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const someFunctionThatShouldOnlyHaveReadonlyAccessToTheState = (
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usersView: View.View<readonly User[], never, never>
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) => Effect.gen(function*() {
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// Do whatever
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const usersCountView = View.map(usersView, a => a.length)
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const users = yield* usersView.get
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yield* Effect.forkScoped(Stream.runForEach(usersView.changes, ...))
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})
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const logUserCount = (users: View.View<readonly User[]>) =>
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Effect.gen(function*() {
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const userCount = View.map(users, users => users.length)
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yield* Console.log(`There are ${yield* userCount.get} users`)
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yield* Stream.runForEach(
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userCount.changes,
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count => Console.log(`There are now ${count} users`),
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)
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})
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const lens = ref.pipe(
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const usersLens = ref.pipe(
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Lens.fromSubscriptionRef,
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Lens.focusObjectOn("users"),
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)
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yield* someFunctionThatShouldOnlyHaveReadonlyAccessToTheState(lens)
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yield* Effect.forkScoped(logUserCount(usersLens))
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```
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Use `Lens.asView` when you want to make that read-only boundary explicit.
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#### Focusing
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This library provides a `View` module with value and error transforms, recovery (`catch`, `catchCause`, `orElse`, `orElseSucceed`, and `retry`), and transforms to narrow the focus of `View`'s, same as Lenses:
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Views can be focused in the same way as Lenses. The `View` module also provides value and error transforms, plus recovery (`catch`, `catchCause`, `orElse`, `orElseSucceed`, and `retry`):
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```typescript
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import { View } from "effect-lens"
|
||||
|
||||
|
||||
@@ -64,7 +64,7 @@ You can also create Lenses manually using `make` by providing:
|
||||
- `get`: an effect that reads the current value,
|
||||
- `changes`: a stream of value changes,
|
||||
- `commit`: an effectful write primitive,
|
||||
- `lock`: an effect that produces the lock used to serialize writes.
|
||||
- `lock`: an effect that produces the lock used to serialize writes and preserve atomicity.
|
||||
|
||||
You can get pretty creative! Here's an example of a Lens that points to a specific key of the browser `LocalStorage`:
|
||||
```typescript
|
||||
@@ -101,9 +101,6 @@ const lens = Effect.all([
|
||||
)
|
||||
```
|
||||
|
||||
Note: while Lens supports asynchronous effects for the proxy logic, we would recommend keeping them synchronous to preserve atomicity.
|
||||
|
||||
|
||||
### Focusing
|
||||
|
||||
Lenses can focus on a nested part of the data type they point to.
|
||||
|
||||
Reference in New Issue
Block a user