fix Hash implemention for Option.none (#2165)

Author: tim-smart

.changeset/lucky-mirrors-know.md

@@ -0,0 +1,5 @@
+---
+"effect": patch
+---
+
+fix Hash implemention for Option.none

packages/effect/src/internal/option.ts

@@ -42,14 +42,15 @@ const SomeProto = Object.assign(Object.create(CommonProto), {
   }
 })
 
+const NoneHash = Hash.hash("None")
 const NoneProto = Object.assign(Object.create(CommonProto), {
   _tag: "None",
   _op: "None",
   [Equal.symbol]<A>(this: Option.None<A>, that: unknown): boolean {
     return isOption(that) && isNone(that)
   },
   [Hash.symbol]<A>(this: Option.None<A>) {
-    return Hash.combine(Hash.hash(this._tag))
+    return NoneHash
   },
   toJSON<A>(this: Option.None<A>) {
     return {

packages/effect/test/Option.test.ts

@@ -1,7 +1,9 @@
 import * as Util from "effect-test/util"
 import * as Chunk from "effect/Chunk"
 import * as E from "effect/Either"
+import * as Equal from "effect/Equal"
 import { pipe } from "effect/Function"
+import * as Hash from "effect/Hash"
 import * as N from "effect/Number"
 import * as _ from "effect/Option"
 import * as S from "effect/String"
@@ -87,6 +89,18 @@ describe("Option", () => {
     expect(inspect(_.some(1))).toEqual(inspect({ _id: "Option", _tag: "Some", value: 1 }))
   })
 
+  it("Equal", () => {
+    expect(Equal.equals(_.some(1), _.some(1))).toEqual(true)
+    expect(Equal.equals(_.some(1), _.some(2))).toEqual(false)
+    expect(Equal.equals(_.none(), _.none())).toEqual(true)
+  })
+
+  it("Hash", () => {
+    expect(Hash.hash(_.some(1))).toEqual(Hash.hash(_.some(1)))
+    expect(Hash.hash(_.some(1)) === Hash.hash(_.some(2))).toEqual(false)
+    expect(Hash.hash(_.none())).toEqual(Hash.hash(_.none()))
+  })
+
   it("getRight", () => {
     expect(_.getRight(E.right(1))).toEqual(_.some(1))
     expect(_.getRight(E.left("a"))).toEqual(_.none())