From 5c60d8b7d3a32386249c7c815260d46d1b76a186 Mon Sep 17 00:00:00 2001
From: Baptiste Langlade <baptouuuu@gmail.com>
Date: Sun, 1 Dec 2024 12:58:44 +0100
Subject: [PATCH] fix Either and Maybe ::memoize() not loading everything

---
 CHANGELOG.md         |  6 ++++++
 proofs/either.php    | 27 +++++++++++++++++++++++++++
 proofs/maybe.php     | 20 ++++++++++++++++++++
 src/Either/Defer.php |  2 +-
 src/Maybe/Defer.php  |  2 +-
 5 files changed, 55 insertions(+), 2 deletions(-)
 create mode 100644 proofs/either.php

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 468634f..3b34c7f 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,11 @@
 # Changelog
 
+## [Unreleased]
+
+### Fixed
+
+- `Innmind\Immutable\Maybe::memoize()` and `Innmind\Immutable\Either::memoize()` was only unwrapping the first layer of the monad. It now recursively unwraps until all the deferred monads are memoized.
+
 ## 5.10.0 - 2024-11-09
 
 ### Added
diff --git a/proofs/either.php b/proofs/either.php
new file mode 100644
index 0000000..4ab566a
--- /dev/null
+++ b/proofs/either.php
@@ -0,0 +1,27 @@
+<?php
+declare(strict_types = 1);
+
+use Innmind\Immutable\Either;
+use Innmind\BlackBox\Set;
+
+return static function() {
+    yield proof(
+        'Either::memoize() any composition',
+        given(Set\Type::any()->filter(static fn($value) => !\is_null($value))),
+        static function($assert, $value) {
+            $loaded = false;
+            $either = Either::defer(static fn() => Either::right($value))
+                ->flatMap(static function() use ($value, &$loaded) {
+                    return Either::defer(static function() use ($value, &$loaded) {
+                        $loaded = true;
+
+                        return Either::right($value);
+                    });
+                });
+
+            $assert->false($loaded);
+            $either->memoize();
+            $assert->true($loaded);
+        },
+    );
+};
diff --git a/proofs/maybe.php b/proofs/maybe.php
index bdff303..1b165aa 100644
--- a/proofs/maybe.php
+++ b/proofs/maybe.php
@@ -43,4 +43,24 @@ static function($assert, $value1, $value2) {
             );
         },
     );
+
+    yield proof(
+        'Maybe::memoize() any composition',
+        given(Set\Type::any()->filter(static fn($value) => !\is_null($value))),
+        static function($assert, $value) {
+            $loaded = false;
+            $maybe = Maybe::defer(static fn() => Maybe::just($value))
+                ->flatMap(static function() use ($value, &$loaded) {
+                    return Maybe::defer(static function() use ($value, &$loaded) {
+                        $loaded = true;
+
+                        return Maybe::just($value);
+                    });
+                });
+
+            $assert->false($loaded);
+            $maybe->memoize();
+            $assert->true($loaded);
+        },
+    );
 };
diff --git a/src/Either/Defer.php b/src/Either/Defer.php
index e962868..fe37f91 100644
--- a/src/Either/Defer.php
+++ b/src/Either/Defer.php
@@ -108,7 +108,7 @@ private function unwrap(): Either
          * @psalm-suppress InaccessibleProperty
          * @psalm-suppress ImpureFunctionCall
          */
-        return $this->value ??= ($this->deferred)();
+        return $this->value ??= ($this->deferred)()->memoize();
     }
 
     /**
diff --git a/src/Maybe/Defer.php b/src/Maybe/Defer.php
index 09d46a4..251e537 100644
--- a/src/Maybe/Defer.php
+++ b/src/Maybe/Defer.php
@@ -107,7 +107,7 @@ private function unwrap(): Maybe
          * @psalm-suppress InaccessibleProperty
          * @psalm-suppress ImpureFunctionCall
          */
-        return $this->value ??= ($this->deferred)();
+        return $this->value ??= ($this->deferred)()->memoize();
     }
 
     /**