MemoMapA MemoMap is used to memoize layer construction and ensure sharing of
layers.
Details
The MemoMap prevents duplicate construction of the same layer instance,
enabling efficient resource sharing across layer dependencies.
Example (Sharing layer construction with a memo map)
import { Context, Effect, Layer } from "effect"
class Database extends Context.Service<Database, {
readonly query: (sql: string) => Effect.Effect<string>
}>()("Database") {}
// Create a custom MemoMap for manual layer building
const program = Effect.gen(function*() {
const memoMap = yield* Layer.makeMemoMap
const scope = yield* Effect.scope
const dbLayer = Layer.succeed(Database, {
query: Effect.fn("Database.query")((sql: string) => Effect.succeed("result"))
})
const context = yield* Layer.buildWithMemoMap(dbLayer, memoMap, scope)
return Context.get(context, Database)
})models
Source effect/Layer.ts:21912 lines
export interface MemoMap {
readonly [const MemoMapTypeId: "~effect/Layer/MemoMap"MemoMapTypeId]: typeof const MemoMapTypeId: "~effect/Layer/MemoMap"MemoMapTypeId
readonly MemoMap.get: <RIn, E, ROut>(layer: Layer<ROut, E, RIn>, scope: Scope.Scope) => Effect<Context.Context<ROut>, E, RIn> | undefinedget: <function (type parameter) RIn in <RIn, E, ROut>(layer: Layer<ROut, E, RIn>, scope: Scope.Scope): Effect<Context.Context<ROut>, E, RIn> | undefinedRIn, function (type parameter) E in <RIn, E, ROut>(layer: Layer<ROut, E, RIn>, scope: Scope.Scope): Effect<Context.Context<ROut>, E, RIn> | undefinedE, function (type parameter) ROut in <RIn, E, ROut>(layer: Layer<ROut, E, RIn>, scope: Scope.Scope): Effect<Context.Context<ROut>, E, RIn> | undefinedROut>(
layer: Layer<ROut, E, RIn>(parameter) layer: {
build: (memoMap: MemoMap, scope: Scope.Scope) => Effect<Context.Context<ROut>, E, RIn>;
pipe: { <A>(this: A): A; <A, B = never>(this: A, ab: (_: A) => B): B; <A, B = never, C = never>(this: A, ab: (_: A) => B, bc: (_: B) => C): C; <A, B = never, C = never, D = never>(this: A, ab: (_: A) => B, bc: (_: B) => C, cd: (_: C) => D): D; <…;
}
interface Layer<in ROut, out E = never, out RIn = never>A Layer describes how to build one or more services for dependency injection.
When to use
Use to model construction of application services for dependency injection,
especially when services have dependencies, can fail during construction, or
need scoped setup and release.
Details
A Layer<ROut, E, RIn> represents ROut as the services this layer
provides, E as the possible errors during layer construction, and RIn as
the services this layer requires as dependencies.
Layer<function (type parameter) ROut in <RIn, E, ROut>(layer: Layer<ROut, E, RIn>, scope: Scope.Scope): Effect<Context.Context<ROut>, E, RIn> | undefinedROut, function (type parameter) E in <RIn, E, ROut>(layer: Layer<ROut, E, RIn>, scope: Scope.Scope): Effect<Context.Context<ROut>, E, RIn> | undefinedE, function (type parameter) RIn in <RIn, E, ROut>(layer: Layer<ROut, E, RIn>, scope: Scope.Scope): Effect<Context.Context<ROut>, E, RIn> | undefinedRIn>,
scope: Scope.Scope(parameter) scope: {
strategy: "sequential" | "parallel";
state: State.Open | State.Closed | State.Empty;
}
import ScopeScope.Scope
) => import EffectEffect<import ContextContext.type Context.Context = /*unresolved*/ anyContext<function (type parameter) ROut in <RIn, E, ROut>(layer: Layer<ROut, E, RIn>, scope: Scope.Scope): Effect<Context.Context<ROut>, E, RIn> | undefinedROut>, function (type parameter) E in <RIn, E, ROut>(layer: Layer<ROut, E, RIn>, scope: Scope.Scope): Effect<Context.Context<ROut>, E, RIn> | undefinedE, function (type parameter) RIn in <RIn, E, ROut>(layer: Layer<ROut, E, RIn>, scope: Scope.Scope): Effect<Context.Context<ROut>, E, RIn> | undefinedRIn> | undefined
readonly MemoMap.getOrElseMemoize: <RIn, E, ROut>(layer: Layer<ROut, E, RIn>, scope: Scope.Scope, build: (memoMap: MemoMap, scope: Scope.Scope) => Effect<Context.Context<ROut>, E, RIn>) => Effect<Context.Context<ROut>, E, RIn>getOrElseMemoize: <function (type parameter) RIn in <RIn, E, ROut>(layer: Layer<ROut, E, RIn>, scope: Scope.Scope, build: (memoMap: MemoMap, scope: Scope.Scope) => Effect<Context.Context<ROut>, E, RIn>): Effect<Context.Context<ROut>, E, RIn>RIn, function (type parameter) E in <RIn, E, ROut>(layer: Layer<ROut, E, RIn>, scope: Scope.Scope, build: (memoMap: MemoMap, scope: Scope.Scope) => Effect<Context.Context<ROut>, E, RIn>): Effect<Context.Context<ROut>, E, RIn>E, function (type parameter) ROut in <RIn, E, ROut>(layer: Layer<ROut, E, RIn>, scope: Scope.Scope, build: (memoMap: MemoMap, scope: Scope.Scope) => Effect<Context.Context<ROut>, E, RIn>): Effect<Context.Context<ROut>, E, RIn>ROut>(
layer: Layer<ROut, E, RIn>(parameter) layer: {
build: (memoMap: MemoMap, scope: Scope.Scope) => Effect<Context.Context<ROut>, E, RIn>;
pipe: { <A>(this: A): A; <A, B = never>(this: A, ab: (_: A) => B): B; <A, B = never, C = never>(this: A, ab: (_: A) => B, bc: (_: B) => C): C; <A, B = never, C = never, D = never>(this: A, ab: (_: A) => B, bc: (_: B) => C, cd: (_: C) => D): D; <…;
}
interface Layer<in ROut, out E = never, out RIn = never>A Layer describes how to build one or more services for dependency injection.
When to use
Use to model construction of application services for dependency injection,
especially when services have dependencies, can fail during construction, or
need scoped setup and release.
Details
A Layer<ROut, E, RIn> represents ROut as the services this layer
provides, E as the possible errors during layer construction, and RIn as
the services this layer requires as dependencies.
Layer<function (type parameter) ROut in <RIn, E, ROut>(layer: Layer<ROut, E, RIn>, scope: Scope.Scope, build: (memoMap: MemoMap, scope: Scope.Scope) => Effect<Context.Context<ROut>, E, RIn>): Effect<Context.Context<ROut>, E, RIn>ROut, function (type parameter) E in <RIn, E, ROut>(layer: Layer<ROut, E, RIn>, scope: Scope.Scope, build: (memoMap: MemoMap, scope: Scope.Scope) => Effect<Context.Context<ROut>, E, RIn>): Effect<Context.Context<ROut>, E, RIn>E, function (type parameter) RIn in <RIn, E, ROut>(layer: Layer<ROut, E, RIn>, scope: Scope.Scope, build: (memoMap: MemoMap, scope: Scope.Scope) => Effect<Context.Context<ROut>, E, RIn>): Effect<Context.Context<ROut>, E, RIn>RIn>,
scope: Scope.Scope(parameter) scope: {
strategy: "sequential" | "parallel";
state: State.Open | State.Closed | State.Empty;
}
import ScopeScope.Scope,
build: (
memoMap: MemoMap,
scope: Scope.Scope
) => Effect<Context.Context<ROut>, E, RIn>
memoMap: MemoMap(parameter) memoMap: {
get: <RIn, E, ROut>(layer: Layer<ROut, E, RIn>, scope: Scope.Scope) => Effect<Context.Context<ROut>, E, RIn> | undefined;
getOrElseMemoize: <RIn, E, ROut>(layer: Layer<ROut, E, RIn>, scope: Scope.Scope, build: (memoMap: MemoMap, scope: Scope.Scope) => Effect<Context.Context<ROut>, E, RIn>) => Effect<Context.Context<ROut>, E, RIn>;
}
scope: Scope.Scope(parameter) scope: {
strategy: "sequential" | "parallel";
state: State.Open | State.Closed | State.Empty;
}
import ScopeScope.Scope) => import EffectEffect<import ContextContext.type Context.Context = /*unresolved*/ anyContext<function (type parameter) ROut in <RIn, E, ROut>(layer: Layer<ROut, E, RIn>, scope: Scope.Scope, build: (memoMap: MemoMap, scope: Scope.Scope) => Effect<Context.Context<ROut>, E, RIn>): Effect<Context.Context<ROut>, E, RIn>ROut>, function (type parameter) E in <RIn, E, ROut>(layer: Layer<ROut, E, RIn>, scope: Scope.Scope, build: (memoMap: MemoMap, scope: Scope.Scope) => Effect<Context.Context<ROut>, E, RIn>): Effect<Context.Context<ROut>, E, RIn>E, function (type parameter) RIn in <RIn, E, ROut>(layer: Layer<ROut, E, RIn>, scope: Scope.Scope, build: (memoMap: MemoMap, scope: Scope.Scope) => Effect<Context.Context<ROut>, E, RIn>): Effect<Context.Context<ROut>, E, RIn>RIn>
) => import EffectEffect<import ContextContext.type Context.Context = /*unresolved*/ anyContext<function (type parameter) ROut in <RIn, E, ROut>(layer: Layer<ROut, E, RIn>, scope: Scope.Scope, build: (memoMap: MemoMap, scope: Scope.Scope) => Effect<Context.Context<ROut>, E, RIn>): Effect<Context.Context<ROut>, E, RIn>ROut>, function (type parameter) E in <RIn, E, ROut>(layer: Layer<ROut, E, RIn>, scope: Scope.Scope, build: (memoMap: MemoMap, scope: Scope.Scope) => Effect<Context.Context<ROut>, E, RIn>): Effect<Context.Context<ROut>, E, RIn>E, function (type parameter) RIn in <RIn, E, ROut>(layer: Layer<ROut, E, RIn>, scope: Scope.Scope, build: (memoMap: MemoMap, scope: Scope.Scope) => Effect<Context.Context<ROut>, E, RIn>): Effect<Context.Context<ROut>, E, RIn>RIn>
}Referenced by 11 symbols