diff --git a/.github/FUNDING.yml b/.github/FUNDING.yml
index 57d8eac..fd9654b 100644
--- a/.github/FUNDING.yml
+++ b/.github/FUNDING.yml
@@ -1 +1,2 @@
-github: loophp
+github: drupol
+custom: ["https://www.paypal.me/drupol"]
diff --git a/.github/workflows/continuous-integration.yml b/.github/workflows/continuous-integration.yml
index 192ce52..e06784b 100644
--- a/.github/workflows/continuous-integration.yml
+++ b/.github/workflows/continuous-integration.yml
@@ -33,7 +33,7 @@ jobs:
               run: echo "::set-output name=dir::$(composer config cache-files-dir)"
 
             - name: Cache dependencies
-              uses: actions/cache@v1
+              uses: actions/cache@v2
               with:
                   path: ${{ steps.composer-cache.outputs.dir }}
                   key: ${{ runner.os }}-composer-${{ hashFiles('**/composer.json') }}
@@ -43,7 +43,7 @@ jobs:
               run: composer install --no-progress --no-suggest --prefer-dist --optimize-autoloader
 
             - name: Run Grumphp
-              run: vendor/bin/grumphp run
+              run: vendor/bin/grumphp run --no-ansi -n
               env:
                   STRYKER_DASHBOARD_API_KEY: ${{ secrets.STRYKER_DASHBOARD_API_KEY }}
 
@@ -51,6 +51,20 @@ jobs:
               run: vendor/bin/psalm --shepherd --stats
               continue-on-error: true
 
-            - name: Scrutinizer
-              run: vendor/bin/ocular code-coverage:upload --format=php-clover build/logs/clover.xml
+            - name: Send Scrutinizer data
+              run: |
+                  wget https://scrutinizer-ci.com/ocular.phar
+                  php ocular.phar code-coverage:upload --format=php-clover build/logs/clover.xml
+              continue-on-error: true
+
+            - name: Infection score report
+              run: |
+                  vendor/bin/infection run -j 2
+              continue-on-error: true
+
+            - name: PHP Insights report
+              run: |
+                  rm -rf composer.lock vendor
+                  composer require nunomaduro/phpinsights --dev
+                  vendor/bin/phpinsights analyse src/ -n
               continue-on-error: true
diff --git a/composer.json b/composer.json
index 0b857c8..d151103 100644
--- a/composer.json
+++ b/composer.json
@@ -18,14 +18,13 @@
         "php": ">= 7.1.3"
     },
     "require-dev": {
-        "drupol/php-conventions": "^1.6.14",
+        "drupol/php-conventions": "^1.7.1",
         "friends-of-phpspec/phpspec-code-coverage": "^4.3.2",
         "infection/infection": "^0.13.6",
-        "phpspec/phpspec": "^5.1.2 || ^6.1.1",
-        "phpstan/phpstan": "^0.12.8",
+        "phpspec/phpspec": "^5.1.2 || ^6.2.1",
+        "phpstan/phpstan": "^0.12.32",
         "phpstan/phpstan-strict-rules": "^0.12",
-        "scrutinizer/ocular": "^1.6",
-        "vimeo/psalm": "^3.8.3"
+        "vimeo/psalm": "^3.12.2"
     },
     "config": {
         "sort-packages": true
diff --git a/src/Combinator.php b/src/Combinator.php
index 56ccb78..bc88e70 100644
--- a/src/Combinator.php
+++ b/src/Combinator.php
@@ -12,13 +12,11 @@
 
 /**
  * Class Combinator.
- *
- * @psalm-immutable
  */
 abstract class Combinator implements CombinatorInterface
 {
     /**
-     * @return Closure
+     * @psalm-pure
      */
     public static function with(): Closure
     {
diff --git a/src/Combinator/A.php b/src/Combinator/A.php
index 565fc25..f09a420 100644
--- a/src/Combinator/A.php
+++ b/src/Combinator/A.php
@@ -10,35 +10,26 @@
 /**
  * Class A.
  *
- * @psalm-template AType
- * @psalm-template BType
- *
- * @psalm-immutable
+ * @template AType
+ * @template BType
  */
 final class A extends Combinator
 {
     /**
-     * @psalm-var callable(AType): BType
-     *
-     * @var callable
+     * @var callable(AType): BType
      */
     private $f;
 
     /**
-     * @psalm-var AType
-     *
-     * @var mixed
+     * @var AType
      */
     private $x;
 
     /**
      * A constructor.
      *
-     * @psalm-param callable(AType): BType $f
-     * @psalm-param AType $x
-     *
-     * @param callable $f
-     * @param mixed $x
+     * @param callable(AType): BType $f
+     * @param AType $x
      */
     public function __construct(callable $f, $x)
     {
@@ -47,7 +38,7 @@ public function __construct(callable $f, $x)
     }
 
     /**
-     * @psalm-return BType
+     * @return BType
      */
     public function __invoke()
     {
diff --git a/src/Combinator/B.php b/src/Combinator/B.php
index 573d72c..880f62b 100644
--- a/src/Combinator/B.php
+++ b/src/Combinator/B.php
@@ -10,45 +10,33 @@
 /**
  * Class B.
  *
- * @psalm-template AType
- * @psalm-template BType
- * @psalm-template CType
- *
- * @psalm-immutable
+ * @template AType
+ * @template BType
+ * @template CType
  */
 final class B extends Combinator
 {
     /**
-     * @psalm-var callable(AType): BType
-     *
-     * @var callable
+     * @var callable(AType): BType
      */
     private $f;
 
     /**
-     * @psalm-var callable(CType): AType
-     *
-     * @var callable
+     * @var callable(CType): AType
      */
     private $g;
 
     /**
-     * @psalm-var CType
-     *
-     * @var mixed
+     * @var CType
      */
     private $x;
 
     /**
      * B constructor.
      *
-     * @psalm-param callable(AType): BType $f
-     * @psalm-param callable(CType): AType $g
-     * @psalm-param CType $x
-     *
-     * @param callable $f
-     * @param callable $g
-     * @param mixed $x
+     * @param callable(AType): BType $f
+     * @param callable(CType): AType $g
+     * @param CType $x
      */
     public function __construct(callable $f, callable $g, $x)
     {
@@ -58,7 +46,7 @@ public function __construct(callable $f, callable $g, $x)
     }
 
     /**
-     * @psalm-return BType
+     * @return BType
      */
     public function __invoke()
     {
@@ -66,20 +54,29 @@ public function __invoke()
     }
 
     /**
-     * @template AParam
-     * @template AReturn
+     * @template NewAType
+     * @template NewBType
+     * @template NewCType
      *
-     * @param callable(AParam): AReturn $f
+     * @param callable(NewAType): (NewBType) $f
      *
-     * @return Closure(callable(mixed): AParam): Closure(mixed): AReturn
+     * @return Closure(Closure(NewCType):(NewAType)):(Closure(NewCType):(NewBType))
      */
     public static function on(callable $f): Closure
     {
         return
-            /** @param callable(mixed): AParam $g */
+            /**
+             * @param callable(NewCType):(NewAType) $g
+             *
+             * @return Closure(NewCType):(NewBType)
+             */
             static function (callable $g) use ($f): Closure {
                 return
-                    /** @param mixed $x */
+                    /**
+                     * @param NewCType $x
+                     *
+                     * @return NewBType
+                     */
                     static function ($x) use ($f, $g) {
                         return (new self($f, $g, $x))();
                     };
diff --git a/src/Combinator/C.php b/src/Combinator/C.php
index 3235a4d..61fffdf 100644
--- a/src/Combinator/C.php
+++ b/src/Combinator/C.php
@@ -10,45 +10,33 @@
 /**
  * Class C.
  *
- * @psalm-template AType
- * @psalm-template BType
- * @psalm-template CType
- *
- * @psalm-immutable
+ * @template AType
+ * @template BType
+ * @template CType
  */
 final class C extends Combinator
 {
     /**
-     * @psalm-var callable(AType): callable(BType): CType
-     *
-     * @var callable
+     * @var callable(AType): callable(BType): CType
      */
     private $f;
 
     /**
-     * @psalm-var BType
-     *
-     * @var mixed
+     * @var BType
      */
     private $x;
 
     /**
-     * @psalm-var AType
-     *
-     * @var mixed
+     * @var AType
      */
     private $y;
 
     /**
      * C constructor.
      *
-     * @psalm-param callable(AType): callable(BType): CType $f
-     * @psalm-param BType $x
-     * @psalm-param AType $y
-     *
-     * @param callable $f
-     * @param mixed $x
-     * @param mixed $y
+     * @param callable(AType): (callable(BType): (CType)) $f
+     * @param BType $x
+     * @param AType $y
      */
     public function __construct(callable $f, $x, $y)
     {
@@ -58,9 +46,7 @@ public function __construct(callable $f, $x, $y)
     }
 
     /**
-     * @psalm-return CType
-     *
-     * @return mixed
+     * @return CType
      */
     public function __invoke()
     {
@@ -72,19 +58,25 @@ public function __invoke()
      * @template NewBType
      * @template NewCType
      *
-     * @psalm-param callable(NewAType): callable(NewBType): NewCType $f
-     *
-     * @param callable(NewAType): NewCType $f
+     * @param callable(NewAType): (callable(NewBType): (NewCType)) $f
      *
-     * @return Closure(NewBType): Closure(NewAType): NewCType
+     * @return Closure(NewBType):(Closure(NewAType):(NewCType))
      */
     public static function on(callable $f): Closure
     {
         return
-            /** @param NewBType $x */
+            /**
+             * @param NewBType $x
+             *
+             * @return Closure(NewAType):(NewCType)
+             */
             static function ($x) use ($f): Closure {
                 return
-                /** @param NewAType $y */
+                /**
+                 * @param NewAType $y
+                 *
+                 * @return NewCType
+                 */
                 static function ($y) use ($f, $x) {
                     return (new self($f, $x, $y))();
                 };
diff --git a/src/Combinator/D.php b/src/Combinator/D.php
index 46775ac..ddc607f 100644
--- a/src/Combinator/D.php
+++ b/src/Combinator/D.php
@@ -10,70 +10,55 @@
 /**
  * Class D.
  *
- * @psalm-template AType
- * @psalm-template BType
- * @psalm-template CType
- * @psalm-template DType
- *
- * @psalm-immutable
+ * @template AType
+ * @template BType
+ * @template CType
+ * @template DType
  */
 final class D extends Combinator
 {
     /**
-     * @psalm-var callable(AType): callable(CType): DType
-     *
-     * @var callable
+     * @var callable(AType): callable(CType): DType
      */
-    private $a;
+    private $f;
 
     /**
-     * @psalm-var AType
-     *
-     * @var mixed
+     * @var callable(BType): CType
      */
-    private $b;
+    private $g;
 
     /**
-     * @psalm-var callable(BType): CType
-     *
-     * @var callable
+     * @var AType
      */
-    private $c;
+    private $x;
 
     /**
-     * @psalm-var BType
-     *
-     * @var mixed
+     * @var BType
      */
-    private $d;
+    private $y;
 
     /**
      * D constructor.
      *
-     * @psalm-param callable(AType): callable(CType): DType $a
-     * @psalm-param AType $b
-     * @psalm-param callable(BType): CType $c
-     * @psalm-param BType $d
-     *
-     * @param callable $a
-     * @param mixed $b
-     * @param callable $c
-     * @param mixed $d
+     * @param callable(AType): (callable(CType): (DType)) $f
+     * @param AType $x
+     * @param callable(BType): CType $g
+     * @param BType $y
      */
-    public function __construct(callable $a, $b, callable $c, $d)
+    public function __construct(callable $f, $x, callable $g, $y)
     {
-        $this->a = $a;
-        $this->b = $b;
-        $this->c = $c;
-        $this->d = $d;
+        $this->f = $f;
+        $this->x = $x;
+        $this->g = $g;
+        $this->y = $y;
     }
 
     /**
-     * @psalm-return DType
+     * @return DType
      */
     public function __invoke()
     {
-        return (($this->a)($this->b))(($this->c)($this->d));
+        return (($this->f)($this->x))(($this->g)($this->y));
     }
 
     /**
@@ -82,22 +67,30 @@ public function __invoke()
      * @template NewCType
      * @template NewDType
      *
-     * @psalm-param callable(NewAType): callable(NewCType): NewDType $f
-     *
-     * @param callable(NewCType): NewDType $f
-     *
-     * @return Closure(NewAType): Closure(Closure(NewBType): NewCType): Closure(NewBType): NewDType
+     * @param callable(NewAType): (Closure(NewCType): (NewDType)) $f
      */
     public static function on(callable $f): Closure
     {
         return
-            /** @param NewAType $x */
+            /**
+             * @param NewAType $x
+             *
+             * @return Closure(callable(NewBType): (NewCType)): (Closure(NewBType): (NewDType))
+             */
             static function ($x) use ($f): Closure {
                 return
-                    /** @param callable(NewBType): NewCType $g */
+                    /**
+                     * @param callable(NewBType): (NewCType) $g
+                     *
+                     * @return Closure(NewBType): (NewDType)
+                     */
                     static function (callable $g) use ($f, $x): Closure {
                         return
-                            /** @param NewBType $y */
+                            /**
+                             * @param NewBType $y
+                             *
+                             * @return NewDType
+                             */
                             static function ($y) use ($f, $x, $g) {
                                 return (new self($f, $x, $g, $y))();
                             };
diff --git a/src/Combinator/E.php b/src/Combinator/E.php
index b6647d1..cbf0a8e 100644
--- a/src/Combinator/E.php
+++ b/src/Combinator/E.php
@@ -10,67 +10,49 @@
 /**
  * Class E.
  *
- * @psalm-template AType
- * @psalm-template BType
- * @psalm-template CType
- * @psalm-template DType
- * @psalm-template EType
- *
- * @psalm-immutable
+ * @template AType
+ * @template BType
+ * @template CType
+ * @template DType
+ * @template EType
  *
  * phpcs:disable Generic.Files.LineLength.TooLong
  */
 final class E extends Combinator
 {
     /**
-     * @psalm-var callable(AType): callable(DType): EType
-     *
-     * @var callable
+     * @var callable(AType): callable(DType): EType
      */
     private $f;
 
     /**
-     * @psalm-var callable(BType): callable(CType): DType
-     *
-     * @var callable
+     * @var callable(BType): callable(CType): DType
      */
     private $g;
 
     /**
-     * @psalm-var AType
-     *
-     * @var mixed
+     * @var AType
      */
     private $x;
 
     /**
-     * @psalm-var BType
-     *
-     * @var mixed
+     * @var BType
      */
     private $y;
 
     /**
-     * @psalm-var CType
-     *
-     * @var mixed
+     * @var CType
      */
     private $z;
 
     /**
      * E constructor.
      *
-     * @psalm-param callable(AType): callable(DType): EType $f
-     * @psalm-param AType $x
-     * @psalm-param callable(BType): callable(CType): DType $g
-     * @psalm-param BType $y
-     * @psalm-param CType $z
-     *
-     * @param callable $f
-     * @param mixed $x
-     * @param callable $g
-     * @param mixed $y
-     * @param mixed $z
+     * @param callable(AType): (callable(DType): (EType)) $f
+     * @param AType $x
+     * @param callable(BType): (callable(CType): (DType)) $g
+     * @param BType $y
+     * @param CType $z
      */
     public function __construct(callable $f, $x, callable $g, $y, $z)
     {
@@ -82,7 +64,7 @@ public function __construct(callable $f, $x, callable $g, $y, $z)
     }
 
     /**
-     * @psalm-return EType
+     * @return EType
      */
     public function __invoke()
     {
@@ -96,27 +78,39 @@ public function __invoke()
      * @template NewDType
      * @template NewEType
      *
-     * @psalm-param callable(NewAType): callable(NewDType): NewEType $f
-     *
-     * @param callable $f
-     *
-     * @psalm-return Closure(NewAType): Closure(callable(NewBType): callable(NewCType): NewDType): Closure(NewBType): Closure(NewCType)
+     * @param callable(NewAType): (callable(NewDType): (NewEType)) $f
      *
-     * @return Closure
+     * @return Closure(NewAType):(Closure(callable(NewBType): (callable(NewCType): (NewDType))):(Closure(NewBType):(Closure(NewCType):(NewEType))))
      */
     public static function on(callable $f): Closure
     {
         return
-            /** @param NewAType $x */
+            /**
+             * @param NewAType $x
+             *
+             * @return Closure(callable(NewBType): callable(NewCType): NewDType):(Closure(NewBType):(Closure(NewCType):(NewEType)))
+             */
             static function ($x) use ($f): Closure {
                 return
-                    /** @psalm-param callable(NewBType): callable(NewCType): NewDType $g */
+                    /**
+                     * @param callable(NewBType): (callable(NewCType): (NewDType)) $g
+                     *
+                     * @return Closure(NewBType): (Closure(NewCType):(NewEType))
+                     */
                     static function (callable $g) use ($f, $x): Closure {
                         return
-                            /** @param NewBType $y */
+                            /**
+                             * @param NewBType $y
+                             *
+                             * @return Closure(NewCType):(NewEType)
+                             */
                             static function ($y) use ($f, $x, $g): Closure {
                                 return
-                                    /** @param NewCType $z */
+                                    /**
+                                     * @param NewCType $z
+                                     *
+                                     * @return NewEType
+                                     */
                                     static function ($z) use ($f, $x, $g, $y) {
                                         return (new self($f, $x, $g, $y, $z))();
                                     };
diff --git a/src/Combinator/F.php b/src/Combinator/F.php
index ac24701..1d6e897 100644
--- a/src/Combinator/F.php
+++ b/src/Combinator/F.php
@@ -10,45 +10,33 @@
 /**
  * Class F.
  *
- * @psalm-template AType
- * @psalm-template BType
- * @psalm-template CType
- *
- * @psalm-immutable
+ * @template AType
+ * @template BType
+ * @template CType
  */
 final class F extends Combinator
 {
     /**
-     * @psalm-var callable(BType): callable(AType): CType
-     *
-     * @var callable
+     * @var callable(BType): (Closure(AType): (CType))
      */
     private $f;
 
     /**
-     * @psalm-var AType
-     *
-     * @var mixed
+     * @var AType
      */
     private $x;
 
     /**
-     * @psalm-var BType
-     *
-     * @var mixed
+     * @var BType
      */
     private $y;
 
     /**
      * F constructor.
      *
-     * @psalm-param AType $x
-     * @psalm-param BType $y
-     * @psalm-param callable(BType): callable(AType): CType $f
-     *
-     * @param mixed $x
-     * @param mixed $y
-     * @param callable $f
+     * @param AType $x
+     * @param BType $y
+     * @param callable(BType): (Closure(AType): (CType)) $f
      */
     public function __construct($x, $y, callable $f)
     {
@@ -58,7 +46,7 @@ public function __construct($x, $y, callable $f)
     }
 
     /**
-     * @psalm-return CType
+     * @return CType
      */
     public function __invoke()
     {
@@ -70,19 +58,25 @@ public function __invoke()
      * @template NewBType
      * @template NewCType
      *
-     * @psalm-param NewAType $a
-     *
-     * @param mixed $a
+     * @param NewAType $a
      *
-     * @return Closure(NewBType): Closure(callable(NewBType): callable(NewAType): NewCType): NewCType
+     * @return Closure(NewBType):(Closure(callable(NewBType): (Closure(NewAType): (NewCType))):(NewCType))
      */
     public static function on($a): Closure
     {
         return
-            /** @param NewBType $b */
+            /**
+             * @param NewBType $b
+             *
+             * @return Closure(callable(NewBType): (Closure(NewAType): (NewCType))):(NewCType)
+             */
             static function ($b) use ($a): Closure {
                 return
-                    /** @psalm-param callable(NewBType): callable(NewAType): NewCType $c */
+                    /**
+                     * @param callable(NewBType): (Closure(NewAType): (NewCType)) $c
+                     *
+                     * @return NewCType
+                     */
                     static function (callable $c) use ($a, $b) {
                         return (new self($a, $b, $c))();
                     };
diff --git a/src/Combinator/G.php b/src/Combinator/G.php
index 263d468..943c522 100644
--- a/src/Combinator/G.php
+++ b/src/Combinator/G.php
@@ -10,55 +10,40 @@
 /**
  * Class G.
  *
- * @psalm-template AType
- * @psalm-template BType
- * @psalm-template CType
- * @psalm-template DType
- *
- * @psalm-immutable
+ * @template AType
+ * @template BType
+ * @template CType
+ * @template DType
  */
 final class G extends Combinator
 {
     /**
-     * @psalm-var callable(AType): callable(BType): CType
-     *
-     * @var callable
+     * @var callable(AType): (callable(BType): (CType))
      */
     private $f;
 
     /**
-     * @psalm-var callable(DType): BType
-     *
-     * @var callable
+     * @var callable(DType): BType
      */
     private $g;
 
     /**
-     * @psalm-var DType
-     *
-     * @var mixed
+     * @var DType
      */
     private $x;
 
     /**
-     * @psalm-var AType
-     *
-     * @var mixed
+     * @var AType
      */
     private $y;
 
     /**
      * G constructor.
      *
-     * @psalm-param callable(AType): callable(BType): CType $f
-     * @psalm-param callable(DType): BType $g
-     * @psalm-param DType $x
-     * @psalm-param AType $y
-     *
-     * @param callable $f
-     * @param callable $g
-     * @param mixed $x
-     * @param mixed $y
+     * @param callable(AType): (callable(BType): (CType)) $f
+     * @param callable(DType): (BType) $g
+     * @param DType $x
+     * @param AType $y
      */
     public function __construct(callable $f, callable $g, $x, $y)
     {
@@ -69,7 +54,7 @@ public function __construct(callable $f, callable $g, $x, $y)
     }
 
     /**
-     * @psalm-return CType
+     * @return CType
      */
     public function __invoke()
     {
@@ -82,22 +67,32 @@ public function __invoke()
      * @template NewCType
      * @template NewDType
      *
-     * @psalm-param callable(NewAType): callable(NewBType): NewCType $f
-     *
-     * @param callable $f
+     * @param callable(NewAType): (callable(NewBType): (NewCType)) $f
      *
-     * @return Closure(callable(NewDType): NewBType): Closure(NewDType): Closure(NewAType): NewCType
+     * @return Closure(callable(NewDType): (NewBType)):(Closure(NewDType):(Closure(NewAType):(NewCType)))
      */
     public static function on(callable $f): Closure
     {
         return
-            /** @param callable(NewDType): NewBType $g */
+            /**
+             * @param callable(NewDType): (NewBType) $g
+             *
+             * @return Closure(NewDType):(Closure(NewAType):(NewCType))
+             */
             static function (callable $g) use ($f): Closure {
                 return
-                    /** @param NewDType $x */
+                    /**
+                     * @param NewDType $x
+                     *
+                     * @return Closure(NewAType):(NewCType)
+                     */
                     static function ($x) use ($f, $g): Closure {
                         return
-                            /** @param NewAType $y */
+                            /**
+                             * @param NewAType $y
+                             *
+                             * @return NewCType
+                             */
                             static function ($y) use ($f, $g, $x) {
                                 return (new self($f, $g, $x, $y))();
                             };
diff --git a/src/Combinator/H.php b/src/Combinator/H.php
index 7139967..be8de48 100644
--- a/src/Combinator/H.php
+++ b/src/Combinator/H.php
@@ -10,45 +10,33 @@
 /**
  * Class H.
  *
- * @psalm-template AType
- * @psalm-template BType
- * @psalm-template CType
- *
- * @psalm-immutable
+ * @template AType
+ * @template BType
+ * @template CType
  */
 final class H extends Combinator
 {
     /**
-     * @psalm-var callable(AType): callable(BType): callable(AType): CType
-     *
-     * @var callable
+     * @var callable(AType): (Closure(BType): (Closure(AType): (CType)))
      */
     private $f;
 
     /**
-     * @psalm-var AType
-     *
-     * @var mixed
+     * @var AType
      */
     private $x;
 
     /**
-     * @psalm-var BType
-     *
-     * @var mixed
+     * @var BType
      */
     private $y;
 
     /**
      * H constructor.
      *
-     * @psalm-param callable(AType): callable(BType): callable(AType): CType $f
-     * @psalm-param AType $x
-     * @psalm-param BType $y
-     *
-     * @param callable $f
-     * @param mixed $x
-     * @param mixed $y
+     * @param callable(AType): (Closure(BType): (Closure(AType): (CType))) $f
+     * @param AType $x
+     * @param BType $y
      */
     public function __construct(callable $f, $x, $y)
     {
@@ -58,7 +46,7 @@ public function __construct(callable $f, $x, $y)
     }
 
     /**
-     * @psalm-return CType
+     * @return CType
      */
     public function __invoke()
     {
@@ -70,19 +58,25 @@ public function __invoke()
      * @template NewBType
      * @template NewCType
      *
-     * @psalm-param callable(NewAType): callable(NewBType): callable(NewAType): NewCType $f
-     *
-     * @param callable $f
+     * @param callable(NewAType): (Closure(NewBType): (Closure(NewAType): (NewCType))) $f
      *
-     * @return Closure(NewAType): Closure(NewBType): NewCType
+     * @return Closure(NewAType):(Closure(NewBType):(NewCType))
      */
     public static function on(callable $f): Closure
     {
         return
-            /** @param NewAType $x */
+            /**
+             * @param NewAType $x
+             *
+             * @return Closure(NewBType):(NewCType)
+             */
             static function ($x) use ($f): Closure {
                 return
-                    /** @param NewBType $y */
+                    /**
+                     * @param NewBType $y
+                     *
+                     * @return NewCType
+                     */
                     static function ($y) use ($f, $x) {
                         return (new self($f, $x, $y))();
                     };
diff --git a/src/Combinator/I.php b/src/Combinator/I.php
index 7bb99ca..17662f3 100644
--- a/src/Combinator/I.php
+++ b/src/Combinator/I.php
@@ -9,25 +9,19 @@
 /**
  * Class I.
  *
- * @psalm-template AType
- *
- * @psalm-immutable
+ * @template AType
  */
 final class I extends Combinator
 {
     /**
-     * @psalm-var AType
-     *
-     * @var mixed
+     * @var AType
      */
     private $x;
 
     /**
      * I constructor.
      *
-     * @psalm-param AType $x
-     *
-     * @param mixed $x
+     * @param AType $x
      */
     public function __construct($x)
     {
@@ -35,7 +29,7 @@ public function __construct($x)
     }
 
     /**
-     * @psalm-return AType
+     * @return AType
      */
     public function __invoke()
     {
@@ -45,9 +39,7 @@ public function __invoke()
     /**
      * @template NewAType
      *
-     * @psalm-param NewAType $x
-     *
-     * @param mixed $x
+     * @param NewAType $x
      *
      * @return NewAType
      */
diff --git a/src/Combinator/J.php b/src/Combinator/J.php
index 66368e3..c335c9e 100644
--- a/src/Combinator/J.php
+++ b/src/Combinator/J.php
@@ -10,53 +10,38 @@
 /**
  * Class J.
  *
- * @psalm-template AType
- * @psalm-template BType
- *
- * @psalm-immutable
+ * @template AType
+ * @template BType
  */
 final class J extends Combinator
 {
     /**
-     * @psalm-var callable(AType): callable(BType): BType
-     *
-     * @var callable
+     * @var callable(AType): (callable(BType): (BType))
      */
     private $f;
 
     /**
-     * @psalm-var AType
-     *
-     * @var mixed
+     * @var AType
      */
     private $x;
 
     /**
-     * @psalm-var BType
-     *
-     * @var mixed
+     * @var BType
      */
     private $y;
 
     /**
-     * @psalm-var AType
-     *
-     * @var mixed
+     * @var AType
      */
     private $z;
 
     /**
      * J constructor.
      *
-     * @psalm-param callable(AType): callable(BType): BType $f
-     * @psalm-param AType $x
-     * @psalm-param BType $y
-     * @psalm-param AType $z
-     *
-     * @param callable $f
-     * @param mixed $x
-     * @param mixed $y
-     * @param mixed $z
+     * @param callable(AType): (callable(BType): (BType)) $f
+     * @param AType $x
+     * @param BType $y
+     * @param AType $z
      */
     public function __construct(callable $f, $x, $y, $z)
     {
@@ -67,7 +52,7 @@ public function __construct(callable $f, $x, $y, $z)
     }
 
     /**
-     * @psalm-return BType
+     * @return BType
      */
     public function __invoke()
     {
@@ -78,24 +63,32 @@ public function __invoke()
      * @template NewAType
      * @template NewBType
      *
-     * @psalm-param callable(NewAType): callable(NewBType): NewBType $f
-     *
-     * @param callable $f
-     *
-     * @psalm-return Closure(NewAType): Closure(NewBType): Closure(NewAType): NewBType
+     * @param callable(NewAType): (callable(NewBType): (NewBType)) $f
      *
-     * @return NewBType
+     * @return Closure(NewAType):(Closure(NewBType):(Closure(NewAType):(NewBType)))
      */
     public static function on(callable $f): Closure
     {
         return
-            /** @param NewAType $x */
+            /**
+             * @param NewAType $x
+             *
+             * @return Closure(NewBType):(Closure(NewAType):(NewBType))
+             */
             static function ($x) use ($f): Closure {
                 return
-                    /** @param NewBType $y */
+                    /**
+                     * @param NewBType $y
+                     *
+                     * @return Closure(NewAType):(NewBType)
+                     */
                     static function ($y) use ($f, $x): Closure {
                         return
-                            /** @param NewAType $z */
+                            /**
+                             * @param NewAType $z
+                             *
+                             * @return NewBType
+                             */
                             static function ($z) use ($f, $x, $y) {
                                 return (new self($f, $x, $y, $z))();
                             };
diff --git a/src/Combinator/K.php b/src/Combinator/K.php
index cdcbd40..8467292 100644
--- a/src/Combinator/K.php
+++ b/src/Combinator/K.php
@@ -10,35 +10,26 @@
 /**
  * Class K.
  *
- * @psalm-template AType
- * @psalm-template BType
- *
- * @psalm-immutable
+ * @template AType
+ * @template BType
  */
 final class K extends Combinator
 {
     /**
-     * @psalm-var AType
-     *
-     * @var mixed
+     * @var AType
      */
     private $x;
 
     /**
-     * @psalm-var BType
-     *
-     * @var mixed
+     * @var BType
      */
     private $y;
 
     /**
      * K constructor.
      *
-     * @psalm-param AType $x
-     * @psalm-param BType $y
-     *
-     * @param mixed $x
-     * @param mixed $y
+     * @param AType $x
+     * @param BType $y
      */
     public function __construct($x, $y)
     {
@@ -47,9 +38,7 @@ public function __construct($x, $y)
     }
 
     /**
-     * @psalm-return AType
-     *
-     * @return mixed
+     * @return AType
      */
     public function __invoke()
     {
@@ -60,16 +49,16 @@ public function __invoke()
      * @template NewAType
      * @template NewBType
      *
-     * @psalm-param NewAType $x
-     *
-     * @param mixed $x
+     * @param NewAType $x
      *
      * @return Closure(NewBType): NewAType
      */
     public static function on($x): Closure
     {
         return
-            /** @param NewBType $y */
+            /**
+             * @param NewBType $y
+             */
             static function ($y) use ($x) {
                 return (new self($x, $y))();
             };
diff --git a/src/Combinator/Ki.php b/src/Combinator/Ki.php
index d506cf2..50c763c 100644
--- a/src/Combinator/Ki.php
+++ b/src/Combinator/Ki.php
@@ -10,35 +10,26 @@
 /**
  * Class Ki.
  *
- * @psalm-template AType
- * @psalm-template BType
- *
- * @psalm-immutable
+ * @template AType
+ * @template BType
  */
 final class Ki extends Combinator
 {
     /**
-     * @psalm-var AType
-     *
-     * @var mixed
+     * @var AType
      */
     private $x;
 
     /**
-     * @psalm-var BType
-     *
-     * @var mixed
+     * @var BType
      */
     private $y;
 
     /**
      * Ki constructor.
      *
-     * @psalm-param AType $x
-     * @psalm-param BType $y
-     *
-     * @param mixed $x
-     * @param mixed $y
+     * @param AType $x
+     * @param BType $y
      */
     public function __construct($x, $y)
     {
@@ -47,7 +38,7 @@ public function __construct($x, $y)
     }
 
     /**
-     * @psalm-return BType
+     * @return BType
      */
     public function __invoke()
     {
@@ -58,16 +49,16 @@ public function __invoke()
      * @template NewAType
      * @template NewBType
      *
-     * @psalm-param NewAType $x
-     *
-     * @param mixed $x
+     * @param NewAType $x
      *
      * @return Closure(NewBType): NewBType
      */
     public static function on($x): Closure
     {
         return
-            /** @param NewBType $y */
+            /**
+             * @param NewBType $y
+             */
             static function ($y) use ($x) {
                 return (new self($x, $y))();
             };
diff --git a/src/Combinator/L.php b/src/Combinator/L.php
index 853941e..932e657 100644
--- a/src/Combinator/L.php
+++ b/src/Combinator/L.php
@@ -9,8 +9,6 @@
 
 /**
  * Class L.
- *
- * @psalm-immutable
  */
 final class L extends Combinator
 {
@@ -26,9 +24,6 @@ final class L extends Combinator
 
     /**
      * L constructor.
-     *
-     * @param callable $f
-     * @param callable $g
      */
     public function __construct(callable $f, callable $g)
     {
@@ -46,10 +41,6 @@ public function __invoke()
 
     /**
      * @psalm-suppress MissingClosureReturnType
-     *
-     * @param callable $a
-     *
-     * @return Closure
      */
     public static function on(callable $a): Closure
     {
diff --git a/src/Combinator/M.php b/src/Combinator/M.php
index 87b8225..bda0daf 100644
--- a/src/Combinator/M.php
+++ b/src/Combinator/M.php
@@ -8,8 +8,6 @@
 
 /**
  * Class M.
- *
- * @psalm-immutable
  */
 final class M extends Combinator
 {
@@ -20,10 +18,6 @@ final class M extends Combinator
 
     /**
      * M constructor.
-     *
-     * @psalm-param callable $f
-     *
-     * @param callable $f
      */
     public function __construct(callable $f)
     {
@@ -39,8 +33,6 @@ public function __invoke()
     }
 
     /**
-     * @param callable $a
-     *
      * @return mixed
      */
     public static function on(callable $a)
diff --git a/src/Combinator/O.php b/src/Combinator/O.php
index f84c9fa..1a8c570 100644
--- a/src/Combinator/O.php
+++ b/src/Combinator/O.php
@@ -10,35 +10,26 @@
 /**
  * Class O.
  *
- * @psalm-template AType
- * @psalm-template BType
- *
- * @psalm-immutable
+ * @template AType
+ * @template BType
  */
 final class O extends Combinator
 {
     /**
-     * @psalm-var callable(callable(AType): BType): AType
-     *
-     * @var callable
+     * @var callable(callable(AType): BType): AType
      */
     private $f;
 
     /**
-     * @psalm-var callable(AType): BType
-     *
-     * @var callable
+     * @var callable(AType): BType
      */
     private $g;
 
     /**
      * O constructor.
      *
-     * @psalm-param callable(callable(AType): BType): AType $f
-     * @psalm-param callable(AType): BType $g
-     *
-     * @param callable(callable(AType): BType): AType $f
-     * @param callable(AType): BType $g
+     * @param callable(callable(AType): (BType)): (AType) $f
+     * @param callable(AType): (BType) $g
      */
     public function __construct(callable $f, callable $g)
     {
@@ -47,7 +38,7 @@ public function __construct(callable $f, callable $g)
     }
 
     /**
-     * @psalm-return BType
+     * @return BType
      */
     public function __invoke()
     {
@@ -58,18 +49,18 @@ public function __invoke()
      * @template NewAType
      * @template NewBType
      *
-     * @psalm-param callable(callable(NewAType): NewBType): NewAType $f
-     *
-     * @param callable $f
-     *
-     * @psalm-return Closure(callable(NewAType): NewBType): NewBType
+     * @param callable(callable(NewAType): (NewBType)): (NewAType) $f
      *
-     * @return Closure
+     * @return Closure(callable(NewAType): (NewBType)): (NewBType)
      */
     public static function on(callable $f): Closure
     {
         return
-            /** @param callable(NewAType): NewBType $g */
+            /**
+             * @param callable(NewAType): (NewBType) $g
+             *
+             * @return NewBType
+             */
             static function (callable $g) use ($f) {
                 return (new self($f, $g))();
             };
diff --git a/src/Combinator/Omega.php b/src/Combinator/Omega.php
index ef4e6ce..0dfb4f4 100644
--- a/src/Combinator/Omega.php
+++ b/src/Combinator/Omega.php
@@ -4,13 +4,10 @@
 
 namespace loophp\combinator\Combinator;
 
-use Closure;
 use loophp\combinator\Combinator;
 
 /**
  * Class Omega.
- *
- * @psalm-immutable
  */
 final class Omega extends Combinator
 {
@@ -21,8 +18,6 @@ final class Omega extends Combinator
 
     /**
      * Omega constructor.
-     *
-     * @param callable $f
      */
     public function __construct(callable $f)
     {
@@ -42,8 +37,6 @@ public function __invoke()
     }
 
     /**
-     * @param callable $f
-     *
      * @return mixed
      */
     public static function on(callable $f)
diff --git a/src/Combinator/Phoenix.php b/src/Combinator/Phoenix.php
index defc451..77462d0 100644
--- a/src/Combinator/Phoenix.php
+++ b/src/Combinator/Phoenix.php
@@ -10,57 +10,42 @@
 /**
  * Class Phoenix.
  *
- * @psalm-template AType
- * @psalm-template BType
- * @psalm-template CType
- * @psalm-template DType
- *
- * @psalm-immutable
+ * @template AType
+ * @template BType
+ * @template CType
+ * @template DType
  *
  * phpcs:disable Generic.Files.LineLength.TooLong
  */
 final class Phoenix extends Combinator
 {
     /**
-     * @psalm-var callable(AType): callable(BType): CType
-     *
-     * @var callable
+     * @var callable(AType): (callable(BType): (CType))
      */
     private $f;
 
     /**
-     * @psalm-var callable(DType): AType
-     *
-     * @var callable
+     * @var callable(DType): AType
      */
     private $g;
 
     /**
-     * @psalm-var callable(DType): BType
-     *
-     * @var callable
+     * @var callable(DType): BType
      */
     private $h;
 
     /**
-     * @psalm-var DType
-     *
-     * @var mixed
+     * @var DType
      */
     private $x;
 
     /**
      * Phoenix constructor.
      *
-     * @psalm-param callable(AType): callable(BType): CType $f
-     * @psalm-param callable(DType): AType $g
-     * @psalm-param callable(DType): BType $h
-     * @psalm-param DType $x
-     *
-     * @param callable $f
-     * @param callable $g
-     * @param callable $h
-     * @param mixed $x
+     * @param callable(AType): (callable(BType): (CType)) $f
+     * @param callable(DType): (AType) $g
+     * @param callable(DType): (BType) $h
+     * @param DType $x
      */
     public function __construct(callable $f, callable $g, callable $h, $x)
     {
@@ -71,7 +56,7 @@ public function __construct(callable $f, callable $g, callable $h, $x)
     }
 
     /**
-     * @psalm-return CType
+     * @return CType
      */
     public function __invoke()
     {
@@ -84,24 +69,30 @@ public function __invoke()
      * @template NewCType
      * @template NewDType
      *
-     * @psalm-param callable(NewAType): callable(NewBType): NewCType $f
-     *
-     * @param callable $f
-     *
-     * @psalm-return Closure(callable(NewDType): NewAType): Closure(callable(NewDType): NewBType): Closure(NewDType): NewCType
-     *
-     * @return Closure
+     * @param callable(NewAType): (callable(NewBType): (NewCType)) $f
      */
     public static function on(callable $f): Closure
     {
         return
-            /** @psalm-param callable(NewDType): NewAType $g */
+            /**
+             * @param callable(NewDType): (NewAType) $g
+             *
+             * @return Closure(callable(NewDType): (NewBType)):(Closure(NewDType):(NewCType))
+             */
             static function (callable $g) use ($f): Closure {
                 return
-                    /** @psalm-param callable(NewDType): NewBType $h */
+                    /**
+                     * @param callable(NewDType): (NewBType) $h
+                     *
+                     * @return Closure(NewDType):(NewCType)
+                     */
                     static function (callable $h) use ($f, $g): Closure {
                         return
-                            /** @psalm-param NewDType $x  */
+                            /**
+                             * @param NewDType $x
+                             *
+                             * @return NewCType
+                             */
                             static function ($x) use ($f, $g, $h) {
                                 return (new self($f, $g, $h, $x))();
                             };
diff --git a/src/Combinator/Psi.php b/src/Combinator/Psi.php
index 82d905f..a5707fe 100644
--- a/src/Combinator/Psi.php
+++ b/src/Combinator/Psi.php
@@ -13,49 +13,37 @@
  * @psalm-template AType
  * @psalm-template BType
  * @psalm-template CType
- *
- * @psalm-immutable
  */
 final class Psi extends Combinator
 {
     /**
-     * @psalm-var callable(AType): callable(AType): BType
-     *
-     * @var callable
+     * @var callable(AType):(callable(AType):(BType))
      */
     private $f;
 
     /**
-     * @psalm-var callable(CType): AType
-     *
-     * @var callable
+     * @var callable(CType):(AType)
      */
     private $g;
 
     /**
-     * @psalm-var CType
-     *
-     * @var mixed
+     * @var CType
      */
     private $x;
 
     /**
-     * @psalm-var CType
-     *
-     * @var mixed
+     * @var CType
      */
     private $y;
 
     /**
      * Psi constructor.
      *
-     * @psalm-param callable(AType): callable(AType): BType $f
-     * @psalm-param callable(CType): AType $g
+     * @psalm-param callable(AType): (callable(AType): (BType)) $f
+     * @psalm-param callable(CType): (AType) $g
      * @psalm-param CType $x
      * @psalm-param CType $y
      *
-     * @param callable $f
-     * @param callable $g
      * @param mixed $x
      * @param mixed $y
      */
@@ -68,7 +56,7 @@ public function __construct(callable $f, callable $g, $x, $y)
     }
 
     /**
-     * @psalm-return BType
+     * @return BType
      */
     public function __invoke()
     {
@@ -80,24 +68,28 @@ public function __invoke()
      * @template NewBType
      * @template NewCType
      *
-     * @psalm-param callable(NewAType): callable(NewAType): NewBType $f
-     *
-     * @param callable $f
-     *
-     * @psalm-return Closure(callable(NewCType): NewAType): Closure(NewCType): Closure(NewCType): NewBType
-     *
-     * @return Closure
+     * @param callable(NewAType): (callable(NewAType): (NewBType)) $f
      */
     public static function on(callable $f): Closure
     {
         return
-            /** @psalm-param callable(NewCType): NewAType $g */
+            /**
+             * @psalm-param callable(NewCType): NewAType $g
+             */
             static function (callable $g) use ($f): Closure {
                 return
-                    /** @psalm-param NewCType $x */
+                    /**
+                     * @psalm-param NewCType $x
+                     *
+                     * @param mixed $x
+                     */
                     static function ($x) use ($f, $g): Closure {
                         return
-                            /** @psalm-param NewCType $y */
+                            /**
+                             * @psalm-param NewCType $y
+                             *
+                             * @param mixed $y
+                             */
                             static function ($y) use ($f, $g, $x) {
                                 return (new self($f, $g, $x, $y))();
                             };
diff --git a/src/Combinator/Q.php b/src/Combinator/Q.php
index f0cc467..dc64d13 100644
--- a/src/Combinator/Q.php
+++ b/src/Combinator/Q.php
@@ -10,45 +10,33 @@
 /**
  * Class Q.
  *
- * @psalm-template AType
- * @psalm-template BType
- * @psalm-template CType
- *
- * @psalm-immutable
+ * @template AType
+ * @template BType
+ * @template CType
  */
 final class Q extends Combinator
 {
     /**
-     * @psalm-var callable(AType): BType
-     *
-     * @var callable
+     * @var callable(AType): BType
      */
     private $f;
 
     /**
-     * @psalm-var callable(BType): CType
-     *
-     * @var callable
+     * @var callable(BType): CType
      */
     private $g;
 
     /**
-     * @psalm-var AType
-     *
-     * @var mixed
+     * @var AType
      */
     private $x;
 
     /**
      * Q constructor.
      *
-     * @psalm-param callable(AType): BType $f
-     * @psalm-param callable(BType): CType $g
-     * @psalm-param AType $x
-     *
-     * @param callable $f
-     * @param callable $g
-     * @param mixed $x
+     * @param callable(AType): BType $f
+     * @param callable(BType): CType $g
+     * @param AType $x
      */
     public function __construct(callable $f, callable $g, $x)
     {
@@ -58,7 +46,7 @@ public function __construct(callable $f, callable $g, $x)
     }
 
     /**
-     * @psalm-return CType
+     * @return CType
      */
     public function __invoke()
     {
@@ -70,21 +58,21 @@ public function __invoke()
      * @template NewBType
      * @template NewCType
      *
-     * @psalm-param callable(NewAType): NewBType $f
-     *
-     * @param callable $f
-     *
-     * @psalm-return Closure(callable(NewBType): NewCType): Closure(NewAType): NewCType
-     *
-     * @return Closure
+     * @param callable(NewAType): (NewBType) $f
      */
     public static function on(callable $f): Closure
     {
         return
-            /** @psalm-param callable(NewBType): NewCType $g */
+            /**
+             * @param callable(NewBType): NewCType $g
+             *
+             * @return \Closure(NewAType):(NewCType)
+             */
             static function (callable $g) use ($f): Closure {
                 return
-                    /** @psalm-param NewAType $x */
+                    /**
+                     * @param NewAType $x
+                     */
                     static function ($x) use ($f, $g) {
                         return (new self($f, $g, $x))();
                     };
diff --git a/src/Combinator/R.php b/src/Combinator/R.php
index 595cda7..654570b 100644
--- a/src/Combinator/R.php
+++ b/src/Combinator/R.php
@@ -10,45 +10,33 @@
 /**
  * Class R.
  *
- * @psalm-template AType
- * @psalm-template BType
- * @psalm-template CType
- *
- * @psalm-immutable
+ * @template AType
+ * @template BType
+ * @template CType
  */
 final class R extends Combinator
 {
     /**
-     * @psalm-var callable(BType): callable(AType): CType
-     *
-     * @var callable
+     * @var callable(BType):(Closure(AType):(CType))
      */
     private $f;
 
     /**
-     * @psalm-var AType
-     *
-     * @var mixed
+     * @var AType
      */
     private $x;
 
     /**
-     * @psalm-var BType
-     *
-     * @var mixed
+     * @var BType
      */
     private $y;
 
     /**
      * R constructor.
      *
-     * @psalm-param AType $x
-     * @psalm-param callable(BType): callable(AType): CType $f
-     * @psalm-param BType $y
-     *
-     * @param mixed $x
-     * @param callable $f
-     * @param mixed $y
+     * @param AType $x
+     * @param callable(BType):(Closure(AType):(CType)) $f
+     * @param BType $y
      */
     public function __construct($x, callable $f, $y)
     {
@@ -58,7 +46,7 @@ public function __construct($x, callable $f, $y)
     }
 
     /**
-     * @psalm-return CType
+     * @return CType
      */
     public function __invoke()
     {
@@ -70,21 +58,25 @@ public function __invoke()
      * @template NewBType
      * @template NewCType
      *
-     * @psalm-param NewAType $x
-     *
      * @param NewAType $x
      *
-     * @psalm-return Closure(callable(NewBType): callable(NewAType): NewCType): Closure(NewBType): NewCType
-     *
-     * @return Closure
+     * @return Closure(callable(NewBType):(Closure(NewAType):(NewCType))):(Closure(NewBType):(NewCType))
      */
     public static function on($x): Closure
     {
         return
-            /** @psalm-param callable(NewBType): callable(NewAType): NewCType $f */
+            /**
+             * @param callable(NewBType):(Closure(NewAType):(NewCType)) $f
+             *
+             * @return Closure(NewBType):(NewCType)
+             */
             static function (callable $f) use ($x): Closure {
                 return
-                    /** @psalm-param NewBType $y */
+                    /**
+                     * @param NewBType $y
+                     *
+                     * @return NewCType
+                     */
                     static function ($y) use ($x, $f) {
                         return (new self($x, $f, $y))();
                     };
diff --git a/src/Combinator/S.php b/src/Combinator/S.php
index 8daf6c2..0398b94 100644
--- a/src/Combinator/S.php
+++ b/src/Combinator/S.php
@@ -10,45 +10,33 @@
 /**
  * Class S.
  *
- * @psalm-template AType
- * @psalm-template BType
- * @psalm-template CType
- *
- * @psalm-immutable
+ * @template AType
+ * @template BType
+ * @template CType
  */
 final class S extends Combinator
 {
     /**
-     * @psalm-var callable(AType): callable(BType): CType
-     *
-     * @var callable
+     * @var callable(AType):(callable(BType):(CType))
      */
     private $f;
 
     /**
-     * @psalm-var callable(AType): BType
-     *
-     * @var callable
+     * @var callable(AType):(BType)
      */
     private $g;
 
     /**
-     * @psalm-var AType
-     *
-     * @var mixed
+     * @var AType
      */
     private $x;
 
     /**
      * S constructor.
      *
-     * @psalm-param callable(AType): callable(BType): CType $f
-     * @psalm-param callable(AType): BType $g
-     * @psalm-param AType $x
-     *
-     * @param callable $f
-     * @param callable $g
-     * @param mixed $x
+     * @param callable(AType):(callable(BType):(CType)) $f
+     * @param callable(AType):(BType) $g
+     * @param AType $x
      */
     public function __construct(callable $f, callable $g, $x)
     {
@@ -58,7 +46,7 @@ public function __construct(callable $f, callable $g, $x)
     }
 
     /**
-     * @psalm-return CType
+     * @return CType
      */
     public function __invoke()
     {
@@ -70,21 +58,23 @@ public function __invoke()
      * @template NewBType
      * @template NewCType
      *
-     * @psalm-param callable(NewAType): callable(NewBType): NewCType $f
-     *
-     * @param callable $f
-     *
-     * @psalm-return Closure(callable(NewAType): NewBType): Closure(NewAType): NewCType
-     *
-     * @return Closure
+     * @param callable(NewAType):(callable(NewBType):(NewCType)) $f
      */
     public static function on(callable $f): Closure
     {
         return
-            /** @psalm-param callable(NewAType): NewBType $g */
+            /**
+             * @param callable(NewAType):(NewBType) $g
+             *
+             * @return Closure(NewAType):(NewCType)
+             */
             static function (callable $g) use ($f): Closure {
                 return
-                    /** @psalm-param NewAType $x */
+                    /**
+                     * @param NewAType $x
+                     *
+                     * @return NewCType
+                     */
                     static function ($x) use ($f, $g) {
                         return (new self($f, $g, $x))();
                     };
diff --git a/src/Combinator/T.php b/src/Combinator/T.php
index 672dc13..5474a8d 100644
--- a/src/Combinator/T.php
+++ b/src/Combinator/T.php
@@ -10,35 +10,26 @@
 /**
  * Class T.
  *
- * @psalm-template AType
- * @psalm-template BType
- *
- * @psalm-immutable
+ * @template AType
+ * @template BType
  */
 final class T extends Combinator
 {
     /**
-     * @psalm-var callable(AType): BType
-     *
-     * @var callable
+     * @var callable(AType): BType
      */
     private $f;
 
     /**
-     * @psalm-var AType
-     *
-     * @var mixed
+     * @var AType
      */
     private $x;
 
     /**
      * T constructor.
      *
-     * @psalm-param AType $x
-     * @psalm-param callable(AType): BType $f
-     *
-     * @param mixed $x
-     * @param callable $f
+     * @param AType $x
+     * @param callable(AType): BType $f
      */
     public function __construct($x, callable $f)
     {
@@ -47,7 +38,7 @@ public function __construct($x, callable $f)
     }
 
     /**
-     * @psalm-return BType
+     * @return BType
      */
     public function __invoke()
     {
@@ -58,20 +49,18 @@ public function __invoke()
      * @template NewAType
      * @template NewBType
      *
-     * @psalm-param NewAType $x
-     *
-     * @param mixed $x
-     *
-     * @psalm-return Closure(callable(NewAType): NewBType): NewBType
-     *
-     * @return Closure
+     * @param NewAType $x
      */
     public static function on($x): Closure
     {
         return
-            /** @psalm-param callable(NewAType): NewBType $f */
+            /**
+             * @param callable(NewAType): NewBType $f
+             *
+             * @return NewBType
+             */
             static function (callable $f) use ($x) {
-            return (new self($x, $f))();
-        };
+                return (new self($x, $f))();
+            };
     }
 }
diff --git a/src/Combinator/U.php b/src/Combinator/U.php
index 1a33516..6af652a 100644
--- a/src/Combinator/U.php
+++ b/src/Combinator/U.php
@@ -9,15 +9,11 @@
 
 /**
  * Class U.
- *
- * @psalm-immutable
  */
 final class U extends Combinator
 {
     /**
-     * @psalm-var callable(callable): callable
-     *
-     * @var callable
+     * @var callable(callable): callable
      */
     private $f;
 
@@ -29,10 +25,7 @@ final class U extends Combinator
     /**
      * U constructor.
      *
-     * @psalm-param callable(callable): callable $f
-     *
-     * @param callable $f
-     * @param callable $g
+     * @param callable(callable): callable $f
      */
     public function __construct(callable $f, callable $g)
     {
@@ -52,18 +45,20 @@ public function __invoke()
     }
 
     /**
-     * @psalm-suppress MissingClosureReturnType
-     * @psalm-suppress MissingClosureParamType
-     * @psalm-suppress MixedArgumentTypeCoercion
-     *
-     * @param callable $a
+     * @suppress MissingClosureReturnType
+     * @suppress MissingClosureParamType
+     * @suppress MixedArgumentTypeCoercion
      *
-     * @return Closure
+     * @param callable(callable): callable $f
      */
-    public static function on(callable $a): Closure
+    public static function on(callable $f): Closure
     {
-        return static function (callable $b) use ($a) {
-            return (new self($a, $b))();
-        };
+        return
+            /**
+             * @return mixed
+             */
+            static function (callable $g) use ($f) {
+                return (new self($f, $g))();
+            };
     }
 }
diff --git a/src/Combinator/V.php b/src/Combinator/V.php
index c562f2c..1383771 100644
--- a/src/Combinator/V.php
+++ b/src/Combinator/V.php
@@ -10,45 +10,33 @@
 /**
  * Class V.
  *
- * @psalm-template AType
- * @psalm-template BType
- * @psalm-template CType
- *
- * @psalm-immutable
+ * @template AType
+ * @template BType
+ * @template CType
  */
 final class V extends Combinator
 {
     /**
-     * @psalm-var callable(AType): callable(BType): CType
-     *
-     * @var callable
+     * @var callable(AType): callable(BType): CType
      */
     private $f;
 
     /**
-     * @psalm-var AType
-     *
-     * @var mixed
+     * @var AType
      */
     private $x;
 
     /**
-     * @psalm-var BType
-     *
-     * @var mixed
+     * @var BType
      */
     private $y;
 
     /**
      * V constructor.
      *
-     * @psalm-param AType $x
-     * @psalm-param BType $y
-     * @psalm-param callable(AType): callable(BType): CType $f
-     *
-     * @param mixed $x
-     * @param mixed $y
-     * @param callable $f
+     * @param AType $x
+     * @param BType $y
+     * @param callable(AType): (callable(BType): (CType)) $f
      */
     public function __construct($x, $y, callable $f)
     {
@@ -58,7 +46,7 @@ public function __construct($x, $y, callable $f)
     }
 
     /**
-     * @psalm-return CType
+     * @return CType
      */
     public function __invoke()
     {
@@ -70,21 +58,25 @@ public function __invoke()
      * @template NewBType
      * @template NewCType
      *
-     * @psalm-param NewAType $x
-     *
-     * @param mixed $x
-     *
-     * @psalm-return Closure(NewBType): Closure(callable(NewAType): callable(NewBType): NewCType): NewCType
+     * @param NewAType $x
      *
-     * @return Closure
+     * @return Closure(NewBType):(Closure(callable(NewAType): (callable(NewBType): (NewCType))):(NewCType))
      */
     public static function on($x): Closure
     {
         return
-            /** @psalm-param NewBType $y */
+            /**
+             * @param NewBType $y
+             *
+             * @return Closure(callable(NewAType): (callable(NewBType): (NewCType))):(NewCType)
+             */
             static function ($y) use ($x): Closure {
                 return
-                    /** @psalm-param callable(NewAType): callable(NewBType): NewCType $f */
+                    /**
+                     * @param callable(NewAType): (callable(NewBType): (NewCType)) $f
+                     *
+                     * @return NewCType
+                     */
                     static function (callable $f) use ($x, $y) {
                         return (new self($x, $y, $f))();
                     };
diff --git a/src/Combinator/W.php b/src/Combinator/W.php
index 62af4d5..c338d6f 100644
--- a/src/Combinator/W.php
+++ b/src/Combinator/W.php
@@ -10,35 +10,26 @@
 /**
  * Class W.
  *
- * @psalm-template AType
- * @psalm-template BType
- *
- * @psalm-immutable
+ * @template AType
+ * @template BType
  */
 final class W extends Combinator
 {
     /**
-     * @psalm-var callable(AType): callable(AType): BType
-     *
-     * @var callable
+     * @var callable(AType): callable(AType): BType
      */
     private $f;
 
     /**
-     * @psalm-var AType
-     *
-     * @var mixed
+     * @var AType
      */
     private $x;
 
     /**
      * W constructor.
      *
-     * @psalm-param callable(AType): callable(AType): BType $f
-     * @psalm-param AType $x
-     *
-     * @param callable $f
-     * @param mixed $x
+     * @param callable(AType): (callable(AType): (BType)) $f
+     * @param AType $x
      */
     public function __construct(callable $f, $x)
     {
@@ -47,7 +38,7 @@ public function __construct(callable $f, $x)
     }
 
     /**
-     * @psalm-return BType
+     * @return BType
      */
     public function __invoke()
     {
@@ -58,18 +49,16 @@ public function __invoke()
      * @template NewAType
      * @template NewBType
      *
-     * @psalm-param callable(NewAType): callable(NewAType): NewBType $f
-     *
-     * @param callable $f
-     *
-     * @psalm-return Closure(NewAType): NewBType
-     *
-     * @return Closure
+     * @param callable(NewAType):(callable(NewAType):(NewBType)) $f
      */
     public static function on(callable $f): Closure
     {
         return
-            /** @psalm-param NewAType $x */
+            /**
+             * @param NewAType $x
+             *
+             * @return NewBType
+             */
             static function ($x) use ($f) {
                 return (new self($f, $x))();
             };
diff --git a/src/Combinator/Y.php b/src/Combinator/Y.php
index f988dd8..39888bf 100644
--- a/src/Combinator/Y.php
+++ b/src/Combinator/Y.php
@@ -9,8 +9,6 @@
 
 /**
  * Class Y.
- *
- * @psalm-immutable
  */
 final class Y extends Combinator
 {
@@ -25,8 +23,6 @@ final class Y extends Combinator
      * Y constructor.
      *
      * @psalm-param callable(callable): Closure $f
-     *
-     * @param callable $f
      */
     public function __construct(callable $f)
     {
@@ -65,10 +61,6 @@ static function (...$arguments) use ($f) {
      * @psalm-suppress MissingClosureReturnType
      * @psalm-suppress MissingClosureParamType
      * @psalm-suppress MixedArgumentTypeCoercion
-     *
-     * @param callable $a
-     *
-     * @return Closure
      */
     public static function on(callable $a): Closure
     {
diff --git a/src/Combinator/Z.php b/src/Combinator/Z.php
index af6676a..42cc209 100644
--- a/src/Combinator/Z.php
+++ b/src/Combinator/Z.php
@@ -9,8 +9,6 @@
 
 /**
  * Class Z.
- *
- * @psalm-immutable
  */
 final class Z extends Combinator
 {
@@ -23,8 +21,6 @@ final class Z extends Combinator
      * Z constructor.
      *
      * @psalm-param callable $f
-     *
-     * @param callable $f
      */
     public function __construct(callable $f)
     {
@@ -65,10 +61,6 @@ static function () use ($f) {
      * @psalm-suppress MissingClosureReturnType
      * @psalm-suppress MissingClosureParamType
      * @psalm-suppress MixedArgumentTypeCoercion
-     *
-     * @param callable $a
-     *
-     * @return Closure
      */
     public static function on(callable $a): Closure
     {
diff --git a/src/Combinators.php b/src/Combinators.php
index 6f2164d..d1e01fc 100644
--- a/src/Combinators.php
+++ b/src/Combinators.php
@@ -40,217 +40,136 @@
  */
 final class Combinators
 {
-    /**
-     * @return Closure
-     */
     public static function A(): Closure
     {
         return A::with();
     }
 
-    /**
-     * @return Closure
-     */
     public static function B(): Closure
     {
         return B::with();
     }
 
-    /**
-     * @return Closure
-     */
     public static function C(): Closure
     {
         return C::with();
     }
 
-    /**
-     * @return Closure
-     */
     public static function D(): Closure
     {
         return D::with();
     }
 
-    /**
-     * @return Closure
-     */
     public static function E(): Closure
     {
         return E::with();
     }
 
-    /**
-     * @return Closure
-     */
     public static function F(): Closure
     {
         return F::with();
     }
 
-    /**
-     * @return Closure
-     */
     public static function G(): Closure
     {
         return G::with();
     }
 
-    /**
-     * @return Closure
-     */
     public static function H(): Closure
     {
         return H::with();
     }
 
-    /**
-     * @return Closure
-     */
     public static function I(): Closure
     {
         return I::with();
     }
 
-    /**
-     * @return Closure
-     */
     public static function J(): Closure
     {
         return J::with();
     }
 
-    /**
-     * @return Closure
-     */
     public static function K(): Closure
     {
         return K::with();
     }
 
-    /**
-     * @return Closure
-     */
     public static function Ki(): Closure
     {
         return Ki::with();
     }
 
-    /**
-     * @return Closure
-     */
     public static function L(): Closure
     {
         return L::with();
     }
 
-    /**
-     * @return Closure
-     */
     public static function M(): Closure
     {
         return M::with();
     }
 
-    /**
-     * @return Closure
-     */
     public static function O(): Closure
     {
         return O::with();
     }
 
-    /**
-     * @return Closure
-     */
     public static function Omega(): Closure
     {
         return Omega::with();
     }
 
-    /**
-     * @return Closure
-     */
     public static function Phoenix(): Closure
     {
         return Phoenix::with();
     }
 
-    /**
-     * @return Closure
-     */
     public static function Psi(): Closure
     {
         return Psi::with();
     }
 
-    /**
-     * @return Closure
-     */
     public static function Q(): Closure
     {
         return Q::with();
     }
 
-    /**
-     * @return Closure
-     */
     public static function R(): Closure
     {
         return R::with();
     }
 
-    /**
-     * @return Closure
-     */
     public static function S(): Closure
     {
         return S::with();
     }
 
-    /**
-     * @return Closure
-     */
     public static function T(): Closure
     {
         return T::with();
     }
 
-    /**
-     * @return Closure
-     */
     public static function U(): Closure
     {
         return U::with();
     }
 
-    /**
-     * @return Closure
-     */
     public static function V(): Closure
     {
         return V::with();
     }
 
-    /**
-     * @return Closure
-     */
     public static function W(): Closure
     {
         return W::with();
     }
 
-    /**
-     * @return Closure
-     */
     public static function Y(): Closure
     {
         return Y::with();
     }
 
-    /**
-     * @return Closure
-     */
     public static function Z(): Closure
     {
         return Z::with();
diff --git a/src/Contract/Combinator.php b/src/Contract/Combinator.php
index 79da03c..3df6b70 100644
--- a/src/Contract/Combinator.php
+++ b/src/Contract/Combinator.php
@@ -6,13 +6,7 @@
 
 use Closure;
 
-/**
- * Interface Combinator.
- */
 interface Combinator
 {
-    /**
-     * @return Closure
-     */
     public static function with(): Closure;
 }
diff --git a/tests/static-analysis/F.php b/tests/static-analysis/F.php
index e0b48ee..884afc7 100644
--- a/tests/static-analysis/F.php
+++ b/tests/static-analysis/F.php
@@ -9,7 +9,7 @@
 /**
  * @param string $x
  * @param int $y
- * @param callable(int): callable(string): bool $f
+ * @param callable(int): (Closure(string): (bool)) $f
  *
  * @return bool
  */
diff --git a/tests/static-analysis/H.php b/tests/static-analysis/H.php
index a3c15fd..7a6a98f 100644
--- a/tests/static-analysis/H.php
+++ b/tests/static-analysis/H.php
@@ -7,7 +7,7 @@
 use loophp\combinator\Combinator\H as Combinator;
 
 /**
- * @param callable(array): callable(bool): callable(array): string $f
+ * @param callable(array): (Closure(bool): (Closure(array): (string))) $f
  * @param array $x
  * @param bool $y
  *
diff --git a/tests/static-analysis/R.php b/tests/static-analysis/R.php
index 1a34fe0..0bf9bfb 100644
--- a/tests/static-analysis/R.php
+++ b/tests/static-analysis/R.php
@@ -8,7 +8,7 @@
 
 /**
  * @param bool $x
- * @param callable(int): callable(bool): string $f
+ * @param callable(int): (Closure(bool): (string)) $f
  * @param int $y
  *
  * @return string
diff --git a/tests/static-analysis/Y.php b/tests/static-analysis/Y.php
index 042ce34..fe90f49 100644
--- a/tests/static-analysis/Y.php
+++ b/tests/static-analysis/Y.php
@@ -9,8 +9,6 @@
 
 /**
  * @param callable(callable): Closure $f
- *
- * @return Closure
  */
 function test(callable $f): Closure
 {
diff --git a/tests/static-analysis/Z.php b/tests/static-analysis/Z.php
index d538b82..2a6790a 100644
--- a/tests/static-analysis/Z.php
+++ b/tests/static-analysis/Z.php
@@ -9,8 +9,6 @@
 
 /**
  * @param callable(callable): Closure $f
- *
- * @return Closure
  */
 function test(callable $f): Closure
 {