feat(breaking): Add ClassTag, improve Effect.serviceConstants, requir…

…e string identifier for all tags (#2028)

Co-authored-by: Tim <hello@timsmart.co>

.changeset/fair-guests-walk.md

@@ -0,0 +1,65 @@
+---
+"@effect/platform-node-shared": minor
+"@effect/platform-browser": minor
+"@effect/opentelemetry": minor
+"@effect/platform-node": minor
+"@effect/experimental": minor
+"@effect/platform-bun": minor
+"@effect/rpc-workers": minor
+"@effect/platform": minor
+"@effect/rpc-http": minor
+"effect": minor
+"@effect/schema": minor
+"@effect/cli": minor
+"@effect/rpc": minor
+---
+
+With this change we now require a string key to be provided for all tags and renames the dear old `Tag` to `GenericTag`, so when previously you could do:
+
+```ts
+import { Effect, Context } from "effect";
+interface Service {
+  readonly _: unique symbol;
+}
+const Service = Context.Tag<
+  Service,
+  {
+    number: Effect.Effect<never, never, number>;
+  }
+>();
+```
+
+you are now mandated to do:
+
+```ts
+import { Effect, Context } from "effect";
+interface Service {
+  readonly _: unique symbol;
+}
+const Service = Context.GenericTag<
+  Service,
+  {
+    number: Effect.Effect<never, never, number>;
+  }
+>("Service");
+```
+
+This makes by default all tags globals and ensures better debuggaility when unexpected errors arise.
+
+Furthermore we introduce a new way of constructing tags that should be considered the new default:
+
+```ts
+import { Effect, Context } from "effect";
+class Service extends Context.Tag("Service")<
+  Service,
+  {
+    number: Effect.Effect<never, never, number>;
+  }
+>() {}
+
+const program = Effect.flatMap(Service, ({ number }) => number).pipe(
+  Effect.flatMap((_) => Effect.log(`number: ${_}`))
+);
+```
+
+this will use "Service" as the key and will create automatically an opaque identifier (the class) to be used at the type level, it does something similar to the above in a single shot.

.changeset/warm-keys-search.md

@@ -0,0 +1,30 @@
+---
+"@effect/platform-node-shared": minor
+"@effect/platform-browser": minor
+"@effect/opentelemetry": minor
+"@effect/platform-node": minor
+"@effect/experimental": minor
+"@effect/platform-bun": minor
+"@effect/rpc-workers": minor
+"@effect/platform": minor
+"@effect/rpc-http": minor
+"effect": minor
+"@effect/schema": minor
+"@effect/cli": minor
+"@effect/rpc": minor
+---
+
+This change enables `Effect.serviceConstants` and `Effect.serviceMembers` to access any constant in the service, not only the effects, namely it is now possible to do:
+
+```ts
+import { Effect, Context } from "effect";
+
+class NumberRepo extends Context.TagClass("NumberRepo")<
+  NumberRepo,
+  {
+    readonly numbers: Array<number>;
+  }
+>() {
+  static numbers = Effect.serviceConstants(NumberRepo).numbers;
+}
+```

packages/cli/examples/naval-fate/store.ts

@@ -23,7 +23,7 @@ export interface NavalFateStore {
   removeMine(x: number, y: number): Effect.Effect<never, never, void>
 }
 
-export const NavalFateStore = Context.Tag<NavalFateStore>()
+export const NavalFateStore = Context.GenericTag<NavalFateStore>("NavalFateStore")
 
 export const make = Effect.gen(function*($) {
   const shipsStore = yield* $(Effect.map(

packages/cli/src/internal/cliConfig.ts

@@ -10,7 +10,7 @@ export const make = (params?: Partial<CliConfig.CliConfig>): CliConfig.CliConfig
 })
 
 /** @internal */
-export const Tag = Context.Tag<CliConfig.CliConfig>()
+export const Tag = Context.GenericTag<CliConfig.CliConfig>("@effect/cli/CliConfig")
 
 /** @internal */
 export const defaultConfig: CliConfig.CliConfig = {

packages/cli/src/internal/command.ts

@@ -136,14 +136,14 @@ const getDescriptor = <Name extends string, R, E, A>(self: Command.Command<Name,
 const makeProto = <Name extends string, R, E, A>(
   descriptor: Descriptor.Command<A>,
   handler: (_: A) => Effect.Effect<R, E, void>,
-  tag?: Context.Tag<any, any>,
+  tag: Context.Tag<any, any>,
   transform: Command.Command.Transform<R, E, A> = identity
 ): Command.Command<Name, R, E, A> => {
   const self = Object.create(Prototype)
   self.descriptor = descriptor
   self.handler = handler
   self.transform = transform
-  self.tag = tag ?? Context.Tag()
+  self.tag = tag
   return self
 }
 
@@ -190,7 +190,8 @@ export const fromDescriptor = dual<
     const self: Command.Command<any, any, any, any> = makeProto(
       descriptor,
       handler ??
-        ((_) => Effect.failSync(() => ValidationError.helpRequested(getDescriptor(self))))
+        ((_) => Effect.failSync(() => ValidationError.helpRequested(getDescriptor(self)))),
+      Context.GenericTag(`@effect/cli/Command/(${Array.from(InternalDescriptor.getNames(descriptor)).join("|")})`)
     )
     return self as any
   }
@@ -302,7 +303,8 @@ export const prompt = <Name extends string, A, R, E>(
       InternalDescriptor.prompt(name, prompt),
       (_) => _.value
     ),
-    handler
+    handler,
+    Context.GenericTag(`@effect/cli/Prompt/${name}`)
   )
 
 /** @internal */

packages/cli/test/Command.test.ts

@@ -33,7 +33,7 @@ const clone = Command.make("clone", {
     }
   })).pipe(Command.withDescription("Clone a repository into a new directory"))
 
-const AddService = Context.Tag<"AddService">()
+const AddService = Context.GenericTag<"AddService">("AddService")
 
 const add = Command.make("add", {
   pathspec: Args.text({ name: "pathspec" })
@@ -138,7 +138,7 @@ interface Messages {
   readonly log: (message: string) => Effect.Effect<never, never, void>
   readonly messages: Effect.Effect<never, never, ReadonlyArray<string>>
 }
-const Messages = Context.Tag<Messages>()
+const Messages = Context.GenericTag<Messages>("Messages")
 const MessagesLive = Layer.sync(Messages, () => {
   const messages: Array<string> = []
   return Messages.of({

packages/cli/test/services/MockConsole.ts

@@ -12,7 +12,7 @@ export interface MockConsole extends Console.Console {
   ) => Effect.Effect<never, never, ReadonlyArray<string>>
 }
 
-export const MockConsole = Context.Tag<Console.Console, MockConsole>(
+export const MockConsole = Context.GenericTag<Console.Console, MockConsole>(
   "effect/Console"
 )
 const pattern = new RegExp(

packages/cli/test/services/MockTerminal.ts

@@ -31,7 +31,7 @@ export declare namespace MockTerminal {
 // Context
 // =============================================================================
 
-export const MockTerminal = Context.Tag<Terminal.Terminal, MockTerminal>(
+export const MockTerminal = Context.GenericTag<Terminal.Terminal, MockTerminal>(
   "@effect/platform/Terminal"
 )
 

packages/effect/src/Context.ts

@@ -37,12 +37,31 @@ export interface Tag<in out Identifier, in out Service> extends Pipeable, Inspec
   of(self: Service): Service
   context(self: Service): Context<Identifier>
   readonly stack?: string | undefined
-  readonly identifier?: unknown
+  readonly key: string
   [Unify.typeSymbol]?: unknown
   [Unify.unifySymbol]?: TagUnify<this>
   [Unify.ignoreSymbol]?: TagUnifyIgnore
 }
 
+/**
+ * @since 2.0.0
+ * @category models
+ */
+export interface TagClassShape<Id, Shape> {
+  readonly [TagTypeId]: {
+    readonly Id: Id
+    readonly Shape: Shape
+  }
+}
+
+/**
+ * @since 2.0.0
+ * @category models
+ */
+export interface TagClass<Self, Id, Shape> extends Tag<Self, Shape> {
+  new(_: never): TagClassShape<Id, Shape>
+}
+
 /**
  * @category models
  * @since 2.0.0
@@ -64,35 +83,32 @@ export declare namespace Tag {
   /**
    * @since 2.0.0
    */
-  export type Service<T extends Tag<any, any>> = T extends Tag<any, infer A> ? A : never
+  export type Service<T extends Tag<any, any> | TagClassShape<any, any>> = T extends Tag<any, infer A> ? A
+    : T extends TagClassShape<any, infer A> ? A
+    : never
   /**
    * @since 2.0.0
    */
-  export type Identifier<T extends Tag<any, any>> = T extends Tag<infer A, any> ? A : never
+  export type Identifier<T extends Tag<any, any> | TagClassShape<any, any>> = T extends Tag<infer A, any> ? A
+    : T extends TagClassShape<infer A, any> ? A
+    : never
 }
 
 /**
  * Creates a new `Tag` instance with an optional key parameter.
  *
- * Specifying the `key` will make the `Tag` global, meaning two tags with the same
- * key will map to the same instance.
- *
- * Note: this is useful for cases where live reload can happen and it is
- * desireable to preserve the instance across reloads.
- *
- * @param key - An optional key that makes the `Tag` global.
+ * @param key - A key that will be used to compare tags.
  *
  * @example
  * import * as Context from "effect/Context"
  *
- * assert.strictEqual(Context.Tag() === Context.Tag(), false)
- * assert.strictEqual(Context.Tag("PORT") === Context.Tag("PORT"), true)
+ * assert.strictEqual(Context.GenericTag("PORT").key === Context.GenericTag("PORT").key, true)
  *
  * @since 2.0.0
  * @category constructors
  */
-export const Tag: <Identifier, Service = Identifier>(identifier?: unknown) => Tag<Identifier, Service> =
-  internal.makeTag
+export const GenericTag: <Identifier, Service = Identifier>(key: string) => Tag<Identifier, Service> =
+  internal.makeGenericTag
 
 const TypeId: unique symbol = internal.TypeId as TypeId
 
@@ -116,14 +132,14 @@ export interface Context<in Services> extends Equal, Pipeable, Inspectable {
   readonly [TypeId]: {
     readonly _Services: Types.Contravariant<Services>
   }
-  readonly unsafeMap: Map<Tag<any, any>, any>
+  readonly unsafeMap: Map<string, any>
 }
 
 /**
  * @since 2.0.0
  * @category constructors
  */
-export const unsafeMake: <Services>(unsafeMap: Map<Tag<any, any>, any>) => Context<Services> = internal.makeContext
+export const unsafeMake: <Services>(unsafeMap: Map<string, any>) => Context<Services> = internal.makeContext
 
 /**
  * Checks if the provided argument is a `Context`.
@@ -148,7 +164,7 @@ export const isContext: (input: unknown) => input is Context<never> = internal.i
  * @example
  * import * as Context from "effect/Context"
  *
- * assert.strictEqual(Context.isTag(Context.Tag()), true)
+ * assert.strictEqual(Context.isTag(Context.GenericTag("Tag")), true)
  *
  * @since 2.0.0
  * @category guards
@@ -174,7 +190,7 @@ export const empty: () => Context<never> = internal.empty
  * @example
  * import * as Context from "effect/Context"
  *
- * const Port = Context.Tag<{ PORT: number }>()
+ * const Port = Context.GenericTag<{ PORT: number }>("Port")
  *
  * const Services = Context.make(Port, { PORT: 8080 })
  *
@@ -193,8 +209,8 @@ export const make: <T extends Tag<any, any>>(tag: T, service: Tag.Service<T>) =>
  * import * as Context from "effect/Context"
  * import { pipe } from "effect/Function"
  *
- * const Port = Context.Tag<{ PORT: number }>()
- * const Timeout = Context.Tag<{ TIMEOUT: number }>()
+ * const Port = Context.GenericTag<{ PORT: number }>("Port")
+ * const Timeout = Context.GenericTag<{ TIMEOUT: number }>("Timeout")
  *
  * const someContext = Context.make(Port, { PORT: 8080 })
  *
@@ -230,8 +246,8 @@ export const add: {
  * import * as Context from "effect/Context"
  * import { pipe } from "effect/Function"
  *
- * const Port = Context.Tag<{ PORT: number }>()
- * const Timeout = Context.Tag<{ TIMEOUT: number }>()
+ * const Port = Context.GenericTag<{ PORT: number }>("Port")
+ * const Timeout = Context.GenericTag<{ TIMEOUT: number }>("Timeout")
  *
  * const Services = pipe(
  *   Context.make(Port, { PORT: 8080 }),
@@ -260,8 +276,8 @@ export const get: {
  * @example
  * import * as Context from "effect/Context"
  *
- * const Port = Context.Tag<{ PORT: number }>()
- * const Timeout = Context.Tag<{ TIMEOUT: number }>()
+ * const Port = Context.GenericTag<{ PORT: number }>("Port")
+ * const Timeout = Context.GenericTag<{ TIMEOUT: number }>("Timeout")
  *
  * const Services = Context.make(Port, { PORT: 8080 })
  *
@@ -287,8 +303,8 @@ export const unsafeGet: {
  * import * as Context from "effect/Context"
  * import * as O from "effect/Option"
  *
- * const Port = Context.Tag<{ PORT: number }>()
- * const Timeout = Context.Tag<{ TIMEOUT: number }>()
+ * const Port = Context.GenericTag<{ PORT: number }>("Port")
+ * const Timeout = Context.GenericTag<{ TIMEOUT: number }>("Timeout")
  *
  * const Services = Context.make(Port, { PORT: 8080 })
  *
@@ -312,8 +328,8 @@ export const getOption: {
  * @example
  * import * as Context from "effect/Context"
  *
- * const Port = Context.Tag<{ PORT: number }>()
- * const Timeout = Context.Tag<{ TIMEOUT: number }>()
+ * const Port = Context.GenericTag<{ PORT: number }>("Port")
+ * const Timeout = Context.GenericTag<{ TIMEOUT: number }>("Timeout")
  *
  * const firstContext = Context.make(Port, { PORT: 8080 })
  * const secondContext = Context.make(Timeout, { TIMEOUT: 5000 })
@@ -341,8 +357,8 @@ export const merge: {
  * import { pipe } from "effect/Function"
  * import * as O from "effect/Option"
  *
- * const Port = Context.Tag<{ PORT: number }>()
- * const Timeout = Context.Tag<{ TIMEOUT: number }>()
+ * const Port = Context.GenericTag<{ PORT: number }>("Port")
+ * const Timeout = Context.GenericTag<{ TIMEOUT: number }>("Timeout")
  *
  * const someContext = pipe(
  *   Context.make(Port, { PORT: 8080 }),
@@ -367,3 +383,9 @@ export const omit: <Services, S extends Array<ValidTagsById<Services>>>(
   ...tags: S
 ) => (self: Context<Services>) => Context<Exclude<Services, { [k in keyof S]: Tag.Identifier<S[k]> }[keyof S]>> =
   internal.omit
+
+/**
+ * @since 2.0.0
+ * @category constructors
+ */
+export const Tag: <const Id extends string>(id: Id) => <Self, Shape>() => TagClass<Self, Id, Shape> = internal.Tag