diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 85478f9..0c15e8d 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -94,7 +94,7 @@ jobs:
         run: "composer normalize --ansi --dry-run"
 
       - name: "Cache cache directory for easy-coding-standard/easy-coding-standard"
-        uses: "actions/cache@v4.0.2"
+        uses: "actions/cache@v4"
         with:
           path: ".build/ecs"
           key: "php-${{ matrix.php-version }}-ecs-${{ github.ref_name }}"
diff --git a/src/Result.php b/src/Result.php
index 47daae0..53728cf 100644
--- a/src/Result.php
+++ b/src/Result.php
@@ -61,7 +61,7 @@ abstract public function err(): Option;
      *
      * @template U
      *
-     * @param callable(T=):U $mapper
+     * @param callable(T):U $mapper
      * @return Result<U,E>
      */
     abstract public function map(callable $mapper): self;
@@ -72,7 +72,7 @@ abstract public function map(callable $mapper): self;
      * @template U
      *
      * @param U $default
-     * @param callable(T=):U $f
+     * @param callable(T):U $f
      *
      * @return U
      */
@@ -83,8 +83,8 @@ abstract public function mapOr($default, callable $f): mixed;
      *
      * @template U
      *
-     * @param callable(E=):U $default
-     * @param callable(T=):U $f
+     * @param callable(E):U $default
+     * @param callable(T):U $f
      *
      * @return U
      */
@@ -95,7 +95,7 @@ abstract public function mapOrElse(callable $default, callable $f): mixed;
      *
      * @template F
      *
-     * @param callable(E=):F $op
+     * @param callable(E):F $op
      * @return Result<T,F>
      */
     abstract public function mapErr(callable $op): self;
@@ -103,7 +103,7 @@ abstract public function mapErr(callable $op): self;
     /**
      * Calls a function with a reference to the contained value if Ok.
      *
-     * @param callable(T=):void $f
+     * @param callable(T):void $f
      *
      * @return Result<T,E>
      */
@@ -112,7 +112,7 @@ abstract public function inspect(callable $f): self;
     /**
      * Calls a function with a reference to the contained value if Err.
      *
-     * @param callable(E=):void $f
+     * @param callable(E):void $f
      *
      * @return Result<T,E>
      */
@@ -172,9 +172,10 @@ abstract public function and(self $res): self;
      * Calls op if the result is Ok, otherwise returns the Err value of self.
      *
      * @template U
+     * @template F
      *
-     * @param callable(T=):Result<U,E> $op
-     * @return Result<U,E>
+     * @param callable(T):Result<U,F> $op
+     * @return Result<U,E|F>
      */
     abstract public function andThen(callable $op): self;
 
@@ -191,26 +192,31 @@ abstract public function or(self $res): self;
     /**
      * Calls op if the result is Err, otherwise returns the Ok value of self.
      *
+     * @template U
      * @template F
      *
-     * @param callable(E=):Result<T,F> $op
-     * @return Result<T,F>
+     * @param callable(E):Result<U,F> $op
+     * @return Result<T|U,F>
      */
     abstract public function orElse(callable $op): self;
 
     /**
      * Unwraps a result, yielding the content of an Ok. Else, it returns optb.
      *
-     * @param T $optb
-     * @return T
+     * @template U
+     *
+     * @param U $optb
+     * @return T|U
      */
     abstract public function unwrapOr($optb): mixed;
 
     /**
      * Unwraps a result, yielding the content of an Ok. If the value is an Err then it calls op with its value.
      *
-     * @param callable(E=):T $op
-     * @return T
+     * @template U
+     *
+     * @param callable(E):U $op
+     * @return T|U
      */
     abstract public function unwrapOrElse(callable $op): mixed;
 }