services: add helper type to extract service type from tag (close #47)

Author: VenomAV

.changeset/forty-jobs-care.md

@@ -0,0 +1,5 @@
+---
+"@effect-mongodb/services": minor
+---
+
+Add helper type to extract service type from tag

packages/services/src/DbService.ts

@@ -14,6 +14,7 @@ export type DbService<K extends string> = Db.Db & Brand.Brand<K>
 
 export type Tag<K extends string> = Context.Tag<DbService<K>, DbService<K>>
 export const Tag = <K extends string>(key: K): Tag<K> => Context.GenericTag<DbService<K>>(key)
+export type Service<T extends Tag<any>> = Context.Tag.Service<T>
 
 export const layerEffect = <DbK extends string, MongoClientK extends string, E = never, R = never>(
   dbTag: Tag<DbK>,

packages/services/src/MongoClientService.ts

@@ -12,6 +12,7 @@ export type MongoClientService<K extends string> = MongoClient.MongoClient & Bra
 
 export type Tag<K extends string> = Context.Tag<MongoClientService<K>, MongoClientService<K>>
 export const Tag = <K extends string>(key: K): Tag<K> => Context.GenericTag<MongoClientService<K>>(key)
+export type Service<T extends Tag<any>> = Context.Tag.Service<T>
 
 export const layerEffect = <MongoClientK extends string, E = never, R = never>(
   clientTag: Tag<MongoClientK>,