Support this argument for Micro.gen

.changeset/early-olives-lay.md

@@ -0,0 +1,5 @@
+---
+"effect": minor
+---
+
+Support `this` argument for `Micro.gen`

packages/effect/src/Micro.ts

@@ -1223,14 +1223,22 @@ export const never: Micro<never> = async<never>(function() {
  * @experimental
  * @category constructors
  */
-export const gen = <Eff extends YieldWrap<Micro<any, any, any>>, AEff>(
-  f: () => Generator<Eff, AEff, never>
+export const gen = <Self, Eff extends YieldWrap<Micro<any, any, any>>, AEff>(
+  ...args:
+    | [self: Self, body: (this: Self) => Generator<Eff, AEff, never>]
+    | [body: () => Generator<Eff, AEff, never>]
 ): Micro<
   AEff,
   [Eff] extends [never] ? never : [Eff] extends [YieldWrap<Micro<infer _A, infer E, infer _R>>] ? E : never,
   [Eff] extends [never] ? never : [Eff] extends [YieldWrap<Micro<infer _A, infer _E, infer R>>] ? R : never
 > =>
   make(function(env, onResult) {
+    let f: () => Generator<Eff, AEff, never>
+    if (args.length === 1) {
+      f = args[0]
+    } else {
+      f = args[1].bind(args[0])
+    }
     const iterator = f() as Iterator<YieldWrap<Micro<any, any, any>>, AEff, any>
     let running = false
     let value: any = undefined

packages/effect/test/Micro.test.ts

@@ -106,12 +106,21 @@ describe.concurrent("Micro", () => {
       Micro.runPromise
     ))
 
-  it("gen", () =>
-    Micro.gen(function*() {
-      const result = yield* Micro.succeed(1)
-      assert.strictEqual(result, 1)
-      return result
-    }).pipe(Micro.runPromise).then((_) => assert.deepStrictEqual(_, 1)))
+  describe("gen", () => {
+    it("gen", () =>
+      Micro.gen(function*() {
+        const result = yield* Micro.succeed(1)
+        assert.strictEqual(result, 1)
+        return result
+      }).pipe(Micro.runPromise).then((_) => assert.deepStrictEqual(_, 1)))
+
+    it("gen with context", () =>
+      Micro.gen({ a: 1, b: 2 }, function*() {
+        const result = yield* Micro.succeed(this.a)
+        assert.strictEqual(result, 1)
+        return result + this.b
+      }).pipe(Micro.runPromise).then((_) => assert.deepStrictEqual(_, 3)))
+  })
 
   describe("forEach", () => {
     it("sequential", () =>