diff --git a/composer.json b/composer.json
index 7ae37f0..cadaaf8 100644
--- a/composer.json
+++ b/composer.json
@@ -13,7 +13,8 @@
         "php": ">=7.1"
     },
     "require-dev": {
-        "phpunit/phpunit": "^7.0"
+        "phpunit/phpunit": "^7.0",
+        "psy/psysh": "@stable"
     },
     "autoload": {
         "psr-4": {
diff --git a/composer.lock b/composer.lock
index dbcf712..04fdd6f 100644
--- a/composer.lock
+++ b/composer.lock
@@ -1,12 +1,45 @@
 {
     "_readme": [
         "This file locks the dependencies of your project to a known state",
-        "Read more about it at https://getcomposer.org/doc/01-basic-usage.md#composer-lock-the-lock-file",
+        "Read more about it at https://getcomposer.org/doc/01-basic-usage.md#installing-dependencies",
         "This file is @generated automatically"
     ],
-    "content-hash": "351b2aa48831d572ce00eda2f6f5e205",
+    "content-hash": "871052e2126565e18c54e279dead3d57",
     "packages": [],
     "packages-dev": [
+        {
+            "name": "dnoegel/php-xdg-base-dir",
+            "version": "0.1",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/dnoegel/php-xdg-base-dir.git",
+                "reference": "265b8593498b997dc2d31e75b89f053b5cc9621a"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/dnoegel/php-xdg-base-dir/zipball/265b8593498b997dc2d31e75b89f053b5cc9621a",
+                "reference": "265b8593498b997dc2d31e75b89f053b5cc9621a",
+                "shasum": ""
+            },
+            "require": {
+                "php": ">=5.3.2"
+            },
+            "require-dev": {
+                "phpunit/phpunit": "@stable"
+            },
+            "type": "project",
+            "autoload": {
+                "psr-4": {
+                    "XdgBaseDir\\": "src/"
+                }
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "MIT"
+            ],
+            "description": "implementation of xdg base directory specification for php",
+            "time": "2014-10-24T07:27:01+00:00"
+        },
         {
             "name": "doctrine/instantiator",
             "version": "1.1.0",
@@ -61,6 +94,93 @@
             ],
             "time": "2017-07-22T11:58:36+00:00"
         },
+        {
+            "name": "jakub-onderka/php-console-color",
+            "version": "0.1",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/JakubOnderka/PHP-Console-Color.git",
+                "reference": "e0b393dacf7703fc36a4efc3df1435485197e6c1"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/JakubOnderka/PHP-Console-Color/zipball/e0b393dacf7703fc36a4efc3df1435485197e6c1",
+                "reference": "e0b393dacf7703fc36a4efc3df1435485197e6c1",
+                "shasum": ""
+            },
+            "require": {
+                "php": ">=5.3.2"
+            },
+            "require-dev": {
+                "jakub-onderka/php-code-style": "1.0",
+                "jakub-onderka/php-parallel-lint": "0.*",
+                "jakub-onderka/php-var-dump-check": "0.*",
+                "phpunit/phpunit": "3.7.*",
+                "squizlabs/php_codesniffer": "1.*"
+            },
+            "type": "library",
+            "autoload": {
+                "psr-0": {
+                    "JakubOnderka\\PhpConsoleColor": "src/"
+                }
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "BSD-2-Clause"
+            ],
+            "authors": [
+                {
+                    "name": "Jakub Onderka",
+                    "email": "jakub.onderka@gmail.com",
+                    "homepage": "http://www.acci.cz"
+                }
+            ],
+            "time": "2014-04-08T15:00:19+00:00"
+        },
+        {
+            "name": "jakub-onderka/php-console-highlighter",
+            "version": "v0.3.2",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/JakubOnderka/PHP-Console-Highlighter.git",
+                "reference": "7daa75df45242c8d5b75a22c00a201e7954e4fb5"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/JakubOnderka/PHP-Console-Highlighter/zipball/7daa75df45242c8d5b75a22c00a201e7954e4fb5",
+                "reference": "7daa75df45242c8d5b75a22c00a201e7954e4fb5",
+                "shasum": ""
+            },
+            "require": {
+                "jakub-onderka/php-console-color": "~0.1",
+                "php": ">=5.3.0"
+            },
+            "require-dev": {
+                "jakub-onderka/php-code-style": "~1.0",
+                "jakub-onderka/php-parallel-lint": "~0.5",
+                "jakub-onderka/php-var-dump-check": "~0.1",
+                "phpunit/phpunit": "~4.0",
+                "squizlabs/php_codesniffer": "~1.5"
+            },
+            "type": "library",
+            "autoload": {
+                "psr-0": {
+                    "JakubOnderka\\PhpConsoleHighlighter": "src/"
+                }
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "MIT"
+            ],
+            "authors": [
+                {
+                    "name": "Jakub Onderka",
+                    "email": "acci@acci.cz",
+                    "homepage": "http://www.acci.cz/"
+                }
+            ],
+            "time": "2015-04-20T18:58:01+00:00"
+        },
         {
             "name": "myclabs/deep-copy",
             "version": "1.7.0",
@@ -106,6 +226,57 @@
             ],
             "time": "2017-10-19T19:58:43+00:00"
         },
+        {
+            "name": "nikic/php-parser",
+            "version": "v4.0.3",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/nikic/PHP-Parser.git",
+                "reference": "bd088dc940a418f09cda079a9b5c7c478890fb8d"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/nikic/PHP-Parser/zipball/bd088dc940a418f09cda079a9b5c7c478890fb8d",
+                "reference": "bd088dc940a418f09cda079a9b5c7c478890fb8d",
+                "shasum": ""
+            },
+            "require": {
+                "ext-tokenizer": "*",
+                "php": ">=7.0"
+            },
+            "require-dev": {
+                "phpunit/phpunit": "^6.5 || ^7.0"
+            },
+            "bin": [
+                "bin/php-parse"
+            ],
+            "type": "library",
+            "extra": {
+                "branch-alias": {
+                    "dev-master": "4.0-dev"
+                }
+            },
+            "autoload": {
+                "psr-4": {
+                    "PhpParser\\": "lib/PhpParser"
+                }
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "BSD-3-Clause"
+            ],
+            "authors": [
+                {
+                    "name": "Nikita Popov"
+                }
+            ],
+            "description": "A PHP parser written in PHP",
+            "keywords": [
+                "parser",
+                "php"
+            ],
+            "time": "2018-07-15T17:25:16+00:00"
+        },
         {
             "name": "phar-io/manifest",
             "version": "1.0.1",
@@ -808,6 +979,80 @@
             ],
             "time": "2018-02-15T05:27:38+00:00"
         },
+        {
+            "name": "psy/psysh",
+            "version": "v0.9.7",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/bobthecow/psysh.git",
+                "reference": "4f5b6c090948773a8bfeea6a0f07ab7d0b24e932"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/bobthecow/psysh/zipball/4f5b6c090948773a8bfeea6a0f07ab7d0b24e932",
+                "reference": "4f5b6c090948773a8bfeea6a0f07ab7d0b24e932",
+                "shasum": ""
+            },
+            "require": {
+                "dnoegel/php-xdg-base-dir": "0.1",
+                "ext-json": "*",
+                "ext-tokenizer": "*",
+                "jakub-onderka/php-console-highlighter": "0.3.*",
+                "nikic/php-parser": "~1.3|~2.0|~3.0|~4.0",
+                "php": ">=5.4.0",
+                "symfony/console": "~2.3.10|^2.4.2|~3.0|~4.0",
+                "symfony/var-dumper": "~2.7|~3.0|~4.0"
+            },
+            "require-dev": {
+                "bamarni/composer-bin-plugin": "^1.2",
+                "hoa/console": "~2.15|~3.16",
+                "phpunit/phpunit": "~4.8.35|~5.0|~6.0|~7.0"
+            },
+            "suggest": {
+                "ext-pcntl": "Enabling the PCNTL extension makes PsySH a lot happier :)",
+                "ext-pdo-sqlite": "The doc command requires SQLite to work.",
+                "ext-posix": "If you have PCNTL, you'll want the POSIX extension as well.",
+                "ext-readline": "Enables support for arrow-key history navigation, and showing and manipulating command history.",
+                "hoa/console": "A pure PHP readline implementation. You'll want this if your PHP install doesn't already support readline or libedit."
+            },
+            "bin": [
+                "bin/psysh"
+            ],
+            "type": "library",
+            "extra": {
+                "branch-alias": {
+                    "dev-develop": "0.9.x-dev"
+                }
+            },
+            "autoload": {
+                "files": [
+                    "src/functions.php"
+                ],
+                "psr-4": {
+                    "Psy\\": "src/"
+                }
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "MIT"
+            ],
+            "authors": [
+                {
+                    "name": "Justin Hileman",
+                    "email": "justin@justinhileman.info",
+                    "homepage": "http://justinhileman.com"
+                }
+            ],
+            "description": "An interactive shell for modern PHP.",
+            "homepage": "http://psysh.org",
+            "keywords": [
+                "REPL",
+                "console",
+                "interactive",
+                "shell"
+            ],
+            "time": "2018-08-11T15:54:43+00:00"
+        },
         {
             "name": "sebastian/code-unit-reverse-lookup",
             "version": "1.0.1",
@@ -1371,6 +1616,263 @@
             "homepage": "https://github.com/sebastianbergmann/version",
             "time": "2016-10-03T07:35:21+00:00"
         },
+        {
+            "name": "symfony/console",
+            "version": "v4.1.3",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/symfony/console.git",
+                "reference": "ca80b8ced97cf07390078b29773dc384c39eee1f"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/symfony/console/zipball/ca80b8ced97cf07390078b29773dc384c39eee1f",
+                "reference": "ca80b8ced97cf07390078b29773dc384c39eee1f",
+                "shasum": ""
+            },
+            "require": {
+                "php": "^7.1.3",
+                "symfony/polyfill-mbstring": "~1.0"
+            },
+            "conflict": {
+                "symfony/dependency-injection": "<3.4",
+                "symfony/process": "<3.3"
+            },
+            "require-dev": {
+                "psr/log": "~1.0",
+                "symfony/config": "~3.4|~4.0",
+                "symfony/dependency-injection": "~3.4|~4.0",
+                "symfony/event-dispatcher": "~3.4|~4.0",
+                "symfony/lock": "~3.4|~4.0",
+                "symfony/process": "~3.4|~4.0"
+            },
+            "suggest": {
+                "psr/log-implementation": "For using the console logger",
+                "symfony/event-dispatcher": "",
+                "symfony/lock": "",
+                "symfony/process": ""
+            },
+            "type": "library",
+            "extra": {
+                "branch-alias": {
+                    "dev-master": "4.1-dev"
+                }
+            },
+            "autoload": {
+                "psr-4": {
+                    "Symfony\\Component\\Console\\": ""
+                },
+                "exclude-from-classmap": [
+                    "/Tests/"
+                ]
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "MIT"
+            ],
+            "authors": [
+                {
+                    "name": "Fabien Potencier",
+                    "email": "fabien@symfony.com"
+                },
+                {
+                    "name": "Symfony Community",
+                    "homepage": "https://symfony.com/contributors"
+                }
+            ],
+            "description": "Symfony Console Component",
+            "homepage": "https://symfony.com",
+            "time": "2018-07-26T11:24:31+00:00"
+        },
+        {
+            "name": "symfony/polyfill-mbstring",
+            "version": "v1.9.0",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/symfony/polyfill-mbstring.git",
+                "reference": "d0cd638f4634c16d8df4508e847f14e9e43168b8"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/symfony/polyfill-mbstring/zipball/d0cd638f4634c16d8df4508e847f14e9e43168b8",
+                "reference": "d0cd638f4634c16d8df4508e847f14e9e43168b8",
+                "shasum": ""
+            },
+            "require": {
+                "php": ">=5.3.3"
+            },
+            "suggest": {
+                "ext-mbstring": "For best performance"
+            },
+            "type": "library",
+            "extra": {
+                "branch-alias": {
+                    "dev-master": "1.9-dev"
+                }
+            },
+            "autoload": {
+                "psr-4": {
+                    "Symfony\\Polyfill\\Mbstring\\": ""
+                },
+                "files": [
+                    "bootstrap.php"
+                ]
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "MIT"
+            ],
+            "authors": [
+                {
+                    "name": "Nicolas Grekas",
+                    "email": "p@tchwork.com"
+                },
+                {
+                    "name": "Symfony Community",
+                    "homepage": "https://symfony.com/contributors"
+                }
+            ],
+            "description": "Symfony polyfill for the Mbstring extension",
+            "homepage": "https://symfony.com",
+            "keywords": [
+                "compatibility",
+                "mbstring",
+                "polyfill",
+                "portable",
+                "shim"
+            ],
+            "time": "2018-08-06T14:22:27+00:00"
+        },
+        {
+            "name": "symfony/polyfill-php72",
+            "version": "v1.9.0",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/symfony/polyfill-php72.git",
+                "reference": "95c50420b0baed23852452a7f0c7b527303ed5ae"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/symfony/polyfill-php72/zipball/95c50420b0baed23852452a7f0c7b527303ed5ae",
+                "reference": "95c50420b0baed23852452a7f0c7b527303ed5ae",
+                "shasum": ""
+            },
+            "require": {
+                "php": ">=5.3.3"
+            },
+            "type": "library",
+            "extra": {
+                "branch-alias": {
+                    "dev-master": "1.9-dev"
+                }
+            },
+            "autoload": {
+                "psr-4": {
+                    "Symfony\\Polyfill\\Php72\\": ""
+                },
+                "files": [
+                    "bootstrap.php"
+                ]
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "MIT"
+            ],
+            "authors": [
+                {
+                    "name": "Nicolas Grekas",
+                    "email": "p@tchwork.com"
+                },
+                {
+                    "name": "Symfony Community",
+                    "homepage": "https://symfony.com/contributors"
+                }
+            ],
+            "description": "Symfony polyfill backporting some PHP 7.2+ features to lower PHP versions",
+            "homepage": "https://symfony.com",
+            "keywords": [
+                "compatibility",
+                "polyfill",
+                "portable",
+                "shim"
+            ],
+            "time": "2018-08-06T14:22:27+00:00"
+        },
+        {
+            "name": "symfony/var-dumper",
+            "version": "v4.1.3",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/symfony/var-dumper.git",
+                "reference": "69e174f4c02ec43919380171c6f7550753299316"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/symfony/var-dumper/zipball/69e174f4c02ec43919380171c6f7550753299316",
+                "reference": "69e174f4c02ec43919380171c6f7550753299316",
+                "shasum": ""
+            },
+            "require": {
+                "php": "^7.1.3",
+                "symfony/polyfill-mbstring": "~1.0",
+                "symfony/polyfill-php72": "~1.5"
+            },
+            "conflict": {
+                "phpunit/phpunit": "<4.8.35|<5.4.3,>=5.0",
+                "symfony/console": "<3.4"
+            },
+            "require-dev": {
+                "ext-iconv": "*",
+                "symfony/process": "~3.4|~4.0",
+                "twig/twig": "~1.34|~2.4"
+            },
+            "suggest": {
+                "ext-iconv": "To convert non-UTF-8 strings to UTF-8 (or symfony/polyfill-iconv in case ext-iconv cannot be used).",
+                "ext-intl": "To show region name in time zone dump",
+                "symfony/console": "To use the ServerDumpCommand and/or the bin/var-dump-server script"
+            },
+            "bin": [
+                "Resources/bin/var-dump-server"
+            ],
+            "type": "library",
+            "extra": {
+                "branch-alias": {
+                    "dev-master": "4.1-dev"
+                }
+            },
+            "autoload": {
+                "files": [
+                    "Resources/functions/dump.php"
+                ],
+                "psr-4": {
+                    "Symfony\\Component\\VarDumper\\": ""
+                },
+                "exclude-from-classmap": [
+                    "/Tests/"
+                ]
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "MIT"
+            ],
+            "authors": [
+                {
+                    "name": "Nicolas Grekas",
+                    "email": "p@tchwork.com"
+                },
+                {
+                    "name": "Symfony Community",
+                    "homepage": "https://symfony.com/contributors"
+                }
+            ],
+            "description": "Symfony mechanism for exploring and dumping PHP variables",
+            "homepage": "https://symfony.com",
+            "keywords": [
+                "debug",
+                "dump"
+            ],
+            "time": "2018-07-26T11:24:31+00:00"
+        },
         {
             "name": "theseer/tokenizer",
             "version": "1.1.0",
@@ -1464,7 +1966,9 @@
     ],
     "aliases": [],
     "minimum-stability": "stable",
-    "stability-flags": [],
+    "stability-flags": {
+        "psy/psysh": 0
+    },
     "prefer-stable": false,
     "prefer-lowest": false,
     "platform": {
diff --git a/src/Reflection/ReflectionFixedFunction.php b/src/Reflection/ReflectionFixedFunction.php
new file mode 100644
index 0000000..cc72f81
--- /dev/null
+++ b/src/Reflection/ReflectionFixedFunction.php
@@ -0,0 +1,21 @@
+<?php
+/**
+ * Copyright 2018 Kacper Donat
+ *
+ * @author Kacper "Kadet" Donat <kacper@kadet.net>
+ *
+ * Full license available in separate LICENSE file
+ */
+
+namespace Kadet\Functional\Reflection;
+
+
+use Kadet\Functional\Utils\FixedFunction;
+
+class ReflectionFixedFunction extends \ReflectionFunction
+{
+    public function __construct(FixedFunction $function)
+    {
+        parent::__construct($function->getDecorated()($function));
+    }
+}
\ No newline at end of file
diff --git a/src/Utils/CurriedFunction.php b/src/Utils/CurriedFunction.php
index db0b9ae..faa32a4 100644
--- a/src/Utils/CurriedFunction.php
+++ b/src/Utils/CurriedFunction.php
@@ -68,7 +68,6 @@ class CurriedFunction extends PartiallyAppliedFunction
         }
 
         $applied = $this->apply(...$args);
-
         if (count($applied->getArguments()) >= $this->threshold) {
             return $applied->call();
         }
diff --git a/src/Utils/FixedFunction.php b/src/Utils/FixedFunction.php
new file mode 100644
index 0000000..e86582d
--- /dev/null
+++ b/src/Utils/FixedFunction.php
@@ -0,0 +1,42 @@
+<?php
+/**
+ * Copyright 2018 Kacper Donat
+ *
+ * @author Kacper "Kadet" Donat <kacper@kadet.net>
+ *
+ * Full license available in separate LICENSE file
+ */
+
+namespace Kadet\Functional\Utils;
+
+
+use function Kadet\Functional\apply;
+use Kadet\Functional\Decorator;
+
+class FixedFunction implements Decorator
+{
+    /**
+     * @var callable
+     */
+    private $fixed;
+
+    /**
+     * FixedFunction constructor.
+     *
+     * @param callable $fixed
+     */
+    public function __construct(callable $fixed)
+    {
+        $this->fixed = $fixed;
+    }
+
+    public function __invoke(...$args)
+    {
+        return ($this->fixed)($this)(...$args);
+    }
+
+    public function getDecorated()
+    {
+        return $this->fixed;
+    }
+}
\ No newline at end of file
diff --git a/src/Utils/PartiallyAppliedFunction.php b/src/Utils/PartiallyAppliedFunction.php
index 65e6681..3d75cfd 100644
--- a/src/Utils/PartiallyAppliedFunction.php
+++ b/src/Utils/PartiallyAppliedFunction.php
@@ -23,7 +23,7 @@ class PartiallyAppliedFunction implements Decorator
     {
         switch (true) {
             case $callable instanceof PartiallyAppliedFunction:
-                $this->callable  = $callable->callable;
+                $this->callable  = $callable->getDecorated();
                 $this->arguments = $callable->prepareArguments($args);
                 break;
 
@@ -63,4 +63,12 @@ class PartiallyAppliedFunction implements Decorator
     {
         return $this->callable;
     }
+
+    public static function fix(callable $callable, ...$args)
+    {
+        $applied = new self($callable, ...$args);
+        array_unshift($applied->arguments, $applied);
+
+        return $applied;
+    }
 }
\ No newline at end of file
diff --git a/src/Utils/index.php b/src/Utils/index.php
index 9bad971..ae82d71 100644
--- a/src/Utils/index.php
+++ b/src/Utils/index.php
@@ -10,6 +10,7 @@
 namespace Kadet\Functional;
 
 use Kadet\Functional\Utils\CurriedFunction;
+use Kadet\Functional\Utils\FixedFunction;
 use Kadet\Functional\Utils\FunctionPipeline;
 use Kadet\Functional\Utils\PartiallyAppliedFunction;
 
@@ -18,12 +19,21 @@ function partial(callable $callable, ...$args): PartiallyAppliedFunction
     return new PartiallyAppliedFunction($callable, ...$args);
 }
 
+function apply(callable $callable, ...$args)
+{
+    $threshold = reflect($callable)->getNumberOfRequiredParameters();
+
+    return count($args) >= $threshold
+        ? $callable(...$args)
+        : partial($callable, ...$args);
+}
+
 function curry(callable $callable, int $threshold = null, ...$args): CurriedFunction
 {
     return new CurriedFunction($callable, $threshold, ...$args);
 }
 
-function uncurry(CurriedFunction $curried)
+function uncurry(CurriedFunction $curried): PartiallyAppliedFunction
 {
     return $curried->uncurry();
 }
@@ -32,3 +42,9 @@ function pipe(...$functions)
 {
     return new FunctionPipeline(...$functions);
 }
+
+function fix(callable $callable, ...$args)
+{
+    $f = new FixedFunction($callable);
+    return $args ? apply($f, ...$args) : $f;
+}
diff --git a/src/functions.php b/src/functions.php
index 8ac6139..d55ac99 100644
--- a/src/functions.php
+++ b/src/functions.php
@@ -6,7 +6,10 @@ use Kadet\Functional\Predicate\AllOfPredicate;
 use Kadet\Functional\Predicate\AnyOfPredicate;
 use Kadet\Functional\Predicate\ClosurePredicate;
 use Kadet\Functional\Predicate\ConstantPredicate;
+use function Kadet\Functional\Predicates\instance;
+use Kadet\Functional\Reflection\ReflectionFixedFunction;
 use Kadet\Functional\Reflection\ReflectionPartiallyAppliedFunction;
+use Kadet\Functional\Utils\FixedFunction;
 use Kadet\Functional\Utils\PartiallyAppliedFunction;
 
 require_once __DIR__.'/Utils/index.php';
@@ -73,6 +76,8 @@ function reflect(callable $callable): \ReflectionFunctionAbstract
     switch (true) {
         case $callable instanceof PartiallyAppliedFunction:
             return new ReflectionPartiallyAppliedFunction($callable);
+        case $callable instanceof FixedFunction:
+            return new ReflectionFixedFunction($callable);
         default:
             return new \ReflectionFunction($callable);
     }
diff --git a/tests/PartialApplicationTest.php b/tests/PartialApplicationTest.php
index f356478..6bed981 100644
--- a/tests/PartialApplicationTest.php
+++ b/tests/PartialApplicationTest.php
@@ -71,4 +71,17 @@ class PartialApplicationTest extends \PHPUnit\Framework\TestCase
             $applied->getArguments()
         );
     }
+
+    public function testYCombinator()
+    {
+        $applied = f\fix(function ($f) use (&$applied) {
+            $this->assertSame($f, $applied);
+
+            return function ($x) {
+                $this->assertEquals(1, $x);
+            };
+        });
+
+        $applied(1);
+    }
 }
\ No newline at end of file