Layer54

Constructors

effectconstConstructs a layer from an effect that produces a single service.effectContextconstConstructs a layer from an effect that produces all services in a Context.effectDiscardconstConstructs a layer from an effect, discarding its value and providing no services.emptyconstAn empty layer that provides no services, cannot fail, has no requirements, and performs no construction or finalization work.fromBuildconstConstructs a Layer from a function that uses a MemoMap and Scope to build the layer.fromBuildMemoconstConstructs a Layer from a function that uses a MemoMap and Scope to build the layer, with automatic memoization.succeedconstConstructs a layer that provides a single service from an already available value.succeedContextconstConstructs a layer that provides all services in an already available Context.suspendconstConstructs a layer lazily using the specified factory.syncconstConstructs a layer lazily that provides a single service.syncContextconstConstructs a layer lazily that provides all services in a Context.

Models

CurrentMemoMapclassContext service for the current MemoMap used in layer construction.LayerinterfaceA Layer describes how to build one or more services for dependency injection.LayerUnifyinterfaceType-level hook that allows Layer values to participate in Unify inference.LayerUnifyIgnoreinterfaceType-level marker used by Unify for Layer types that should be ignored during unification.MemoMapinterfaceA MemoMap is used to memoize layer construction and ensure sharing of layers.VarianceinterfaceThe variance interface for Layer type parameters.

Getters

isLayerconstReturns true if the specified value is a Layer, false otherwise.

Sequencing

flatMapconstConstructs a layer dynamically based on the output of this layer.tapconstPerforms the specified effect if this layer succeeds.tapCauseconstPerforms the specified effect when this layer fails with any cause.tapErrorconstPerforms the specified effect if this layer fails.

Destructors

buildconstBuilds a layer into a scoped value.buildWithScopeconstBuilds a layer using an explicit scope.

Converting

launchconstBuilds this layer and keeps it alive until the returned effect is interrupted.unwrapconstUnwraps a Layer from an Effect, flattening the nested structure.

Error Handling

catchCauseconstRecovers from any failure cause by switching to another layer.catchTagconstRecovers from specific tagged errors.orDieconstConverts layer construction failures into defects, removing them from the layer's error type.

Layers

freshconstCreates a fresh version of this layer that will not be shared.

Memo Map

buildWithMemoMapconstBuilds a layer into an Effect value, using the specified MemoMap to memoize the layer construction.forkMemoMapconstConstructs a child MemoMap effectfully, allowing it to reuse layers already memoized in the parent while isolating any new layer allocations to the child map.forkMemoMapUnsafeconstConstructs a child MemoMap synchronously, allowing it to reuse layers already memoized in the parent while isolating any new layer allocations to the child map.makeMemoMapconstConstructs a MemoMap effectfully so it can be used to build additional layers.makeMemoMapUnsafeconstConstructs a MemoMap synchronously so it can be used to build additional layers.

Options

SpanOptionsinterfaceRepresents options that can be used to control the behavior of spans created for layers.

Providing Services

provideconstFeeds the output services of the dependency layer into the requirements of this layer, returning a layer that only provides the services from this layer.provideMergeconstFeeds the output services of the dependency layer into the requirements of this layer, returning a layer that provides both sets of services.updateServiceconstUpdates a service in the context with a new implementation.

Testing

mockconstCreates a mock layer for testing purposes.PartialEffectfultypeA utility type for creating partial mocks of services in testing.

Tracing

parentSpanconstConstructs a layer that provides an existing span as the current parent span.spanconstConstructs a new Layer which creates a span and registers it as the current parent span.withParentSpanconstWraps a layer so spans created during its construction use the supplied span as their parent.withSpanconstWraps a Layer with a new tracing span, making all operations in the layer constructor part of the named trace span.

Utility Types

AnyinterfaceA type-level constraint for working with any Layer type.ErrortypeExtracts the error type (E) from a Layer type.satisfiesErrorTypeconstEnsures that a layer's error type extends a given type E.satisfiesServicesTypeconstEnsures that a layer's requirements type extends a given type R.satisfiesSuccessTypeconstEnsures that a layer's success type extends a given type ROut.ServicestypeExtracts the service requirements (RIn) from a Layer type.SuccesstypeExtracts the service output type (ROut) from a Layer type.

Zipping

mergeconstMerges this layer with another layer concurrently, producing a new layer with combined input, error, and output types.mergeAllconstCombines all the provided layers concurrently, creating a new layer with merged input, error, and output types.