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122 lines
2.1 KiB
Markdown
122 lines
2.1 KiB
Markdown
# Reactivity API: Core
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<br/>
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:::warning
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Yielding is not allowed in any stable or reactive scope. Strict mode will check
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for this.
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:::
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## root()
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Creates and runs a function in a new stable scope.
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- **Type**
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```luau
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function root<T...>(fn: (() -> ()) -> T...): (() -> (), T...)
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```
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- **Details**
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Returns a function to destroy the root scope. Also passes this function as
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the first argument into its callback.
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All values returned by the callback are also returned following the destructor.
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## source()
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Creates a new source with the given value.
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- **Type**
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```luau
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function source<T>(value: T): Source<T>
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type Source<T> =
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() -> T -- get
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& (T) -> () -- set
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```
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- **Details**
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Calling the returned source with no argument will return its stored value,
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calling with an argument will set a new value.
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- **Example**
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```luau
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local count = source(0)
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count() -- 0
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count(count() + 1) -- 1
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```
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## effect()
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Runs a side-effect in a new reactive scope on source update.
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- **Type**
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```luau
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function effect(callback: () -> ())
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```
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- **Details**
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Any time a source referenced in the callback is updated, the callback will
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be reran.
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The callback is ran once immediately.
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- **Example**
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```luau
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local num = source(1)
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effect(function()
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print(num())
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end)
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-- prints 1
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num(num() + 1)
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-- prints 2
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```
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## derive()
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Derives a new source in a new reactive scope from existing sources.
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- **Type**
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```luau
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function derive<T>(source: () -> T): () -> T
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```
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- **Details**
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The derived source will have its value recalculated when any source source
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it derives from is updated.
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Anytime its value is recalculated it is also cached, subsequent calls will
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retun this cached value until it recalculates again.
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The callback is ran once immediately.
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- **Example**
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```luau
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local count = source(0)
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local text = derive(function() return `count: {count()}` end)
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text() -- "count: 0"
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count(1)
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text() -- "count: 1"
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```
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