From b1c3409839edfa30c3500eee8b1500cae3f822c9 Mon Sep 17 00:00:00 2001
From: Michael Arnaldi <arnaldimichael@gmail.com>
Date: Tue, 4 Oct 2022 16:58:48 +0000
Subject: [PATCH] chore: improve object equality, fix eval and tag

---
 .changeset/weak-melons-ring.md             |  5 ++++
 packages/stdlib/_src/io/Eval/definition.ts | 30 +++++++++++++++++++---
 packages/stdlib/_src/service/Tag.ts        |  8 +++++-
 packages/stdlib/_src/structure/Equals.ts   |  9 +++++++
 4 files changed, 48 insertions(+), 4 deletions(-)
 create mode 100644 .changeset/weak-melons-ring.md

diff --git a/.changeset/weak-melons-ring.md b/.changeset/weak-melons-ring.md
new file mode 100644
index 00000000..e935c70d
--- /dev/null
+++ b/.changeset/weak-melons-ring.md
@@ -0,0 +1,5 @@
+---
+"@tsplus/stdlib": patch
+---
+
+Improve Equals on Object, fix Tag/Eval equality
diff --git a/packages/stdlib/_src/io/Eval/definition.ts b/packages/stdlib/_src/io/Eval/definition.ts
index 6c5a44a7..ad7b3b10 100644
--- a/packages/stdlib/_src/io/Eval/definition.ts
+++ b/packages/stdlib/_src/io/Eval/definition.ts
@@ -49,33 +49,57 @@ export function unifyEval<X extends Eval<any>>(
 }
 
 export interface Succeed<A> extends Eval<A> {}
-export class Succeed<A> {
+export class Succeed<A> implements Equals {
   readonly _tag = "Succeed"
 
   readonly [EvalSym]: EvalSym = EvalSym
   readonly [_A]!: () => A
 
   constructor(readonly a: Lazy<A>) {}
+
+  [Equals.sym](that: unknown) {
+    return this === that
+  }
+
+  [Hash.sym]() {
+    return Hash.randomCached(this)
+  }
 }
 
 export interface Suspend<A> extends Eval<A> {}
-export class Suspend<A> {
+export class Suspend<A> implements Equals {
   readonly _tag = "Suspend"
 
   readonly [EvalSym]: EvalSym = EvalSym
   readonly [_A]!: () => A
 
   constructor(readonly f: Lazy<EvalInternal<A>>) {}
+
+  [Equals.sym](that: unknown) {
+    return this === that
+  }
+
+  [Hash.sym]() {
+    return Hash.randomCached(this)
+  }
 }
 
 export interface FlatMap<A, B> extends Eval<B> {}
-export class FlatMap<A, B> {
+export class FlatMap<A, B> implements Equals {
   readonly _tag = "FlatMap"
 
   readonly [EvalSym]: EvalSym = EvalSym
   readonly [_A]!: () => A
 
   constructor(readonly value: EvalInternal<A>, readonly cont: (a: A) => EvalInternal<B>) {}
+
+  [Equals.sym](that: unknown) {
+    return this === that
+  }
+
+  [Hash.sym]() {
+    return Hash.randomCached(this)
+  }
 }
 
 export interface EvalF extends HKT {
diff --git a/packages/stdlib/_src/service/Tag.ts b/packages/stdlib/_src/service/Tag.ts
index 490a3d1e..80eb5aaf 100644
--- a/packages/stdlib/_src/service/Tag.ts
+++ b/packages/stdlib/_src/service/Tag.ts
@@ -14,6 +14,12 @@ export const Tag: TagOps = Object.assign(
     [Tag.sym]: identity,
     toEnv(value) {
       return Env(this, value)
+    },
+    [Equals.sym](that) {
+      return this === that
+    },
+    [Hash.sym]() {
+      return Hash.randomCached(this)
     }
   }),
   {
@@ -25,7 +31,7 @@ export const Tag: TagOps = Object.assign(
 /**
  * @tsplus type Tag
  */
-export interface Tag<in out S> {
+export interface Tag<in out S> extends Equals {
   readonly [Tag.sym]: (_: S) => S
 
   toEnv(value: S): Service.Env<S>
diff --git a/packages/stdlib/_src/structure/Equals.ts b/packages/stdlib/_src/structure/Equals.ts
index 9217313d..959c191b 100644
--- a/packages/stdlib/_src/structure/Equals.ts
+++ b/packages/stdlib/_src/structure/Equals.ts
@@ -59,6 +59,15 @@ const protoMap = new Map<any, (a: any, b: any) => boolean>([
   [
     Object.prototype,
     (a: object, b: object) => {
+      if ("_tag" in a) {
+        if ("_tag" in b) {
+          if (a["_tag"] !== b["_tag"]) {
+            return false
+          }
+        } else {
+          return false
+        }
+      }
       const keysA = Object.keys(a).sort()
       const keysB = Object.keys(b).sort()
       if (keysA.length !== keysB.length) {