Db - add layer constructors for DbService

src/Db.ts

@@ -5,8 +5,10 @@ import type * as Brand from "effect/Brand"
 import * as Context from "effect/Context"
 import * as Effect from "effect/Effect"
 import * as F from "effect/Function"
+import * as Layer from "effect/Layer"
 import type { Db } from "mongodb"
 import * as DocumentCollection from "./DocumentCollection.js"
+import * as MongoClient from "./MongoClient.js"
 import type * as MongoError from "./MongoError.js"
 
 export const collection: {
@@ -24,3 +26,29 @@ export type DbService<K extends string> = {
 } & Brand.Brand<K>
 
 export const Tag = <K extends string>(key: K) => Context.GenericTag<DbService<K>>(key)
+export type TagType<K extends string> = ReturnType<typeof Tag<K>>
+
+export const fromEffect = <DbK extends string, MongoClientK extends string, E = never, R = never>(
+  dbTag: TagType<DbK>,
+  clientTag: MongoClient.TagType<MongoClientK>,
+  dbName: Effect.Effect<string, E, R>
+) =>
+  Layer.effect(
+    dbTag,
+    Effect.gen(function*(_) {
+      const { client } = yield* _(clientTag)
+      const dbName_ = yield* _(dbName)
+      const db = yield* _(
+        client,
+        Effect.flatMap((client) => MongoClient.db(client, dbName_)),
+        Effect.cached
+      )
+      return dbTag.of({ db } as DbService<DbK>) // TODO fix cast using branded ctor
+    })
+  )
+
+export const fromConst = <DbK extends string, MongoClientK extends string>(
+  dbTag: TagType<DbK>,
+  clientTag: MongoClient.TagType<MongoClientK>,
+  dbName: string
+) => fromEffect(dbTag, clientTag, Effect.succeed(dbName))

src/MongoClient.ts

@@ -30,3 +30,4 @@ export type MongoClientService<K extends string> = {
 } & Brand.Brand<K>
 
 export const Tag = <K extends string>(key: K) => Context.GenericTag<MongoClientService<K>>(key)
+export type TagType<K extends string> = ReturnType<typeof Tag<K>>