diff --git a/src/Exception/ApplicationException.php b/src/Exception/ApplicationException.php
new file mode 100644
index 0000000..82a4d0e
--- /dev/null
+++ b/src/Exception/ApplicationException.php
@@ -0,0 +1,16 @@
+<?php
+/**
+ * Copyright 2018 Kacper Donat
+ *
+ * @author Kacper "Kadet" Donat <kacper@kadet.net>
+ *
+ * Full license available in separate LICENSE file
+ */
+
+namespace Kadet\Functional\Exception;
+
+
+class ApplicationException extends FunctionalException
+{
+
+}
\ No newline at end of file
diff --git a/src/Exception/FunctionalException.php b/src/Exception/FunctionalException.php
new file mode 100644
index 0000000..cb6549d
--- /dev/null
+++ b/src/Exception/FunctionalException.php
@@ -0,0 +1,16 @@
+<?php
+/**
+ * Copyright 2018 Kacper Donat
+ *
+ * @author Kacper "Kadet" Donat <kacper@kadet.net>
+ *
+ * Full license available in separate LICENSE file
+ */
+
+namespace Kadet\Functional\Exception;
+
+
+class FunctionalException extends \RuntimeException
+{
+
+}
\ No newline at end of file
diff --git a/src/Reflection/ReflectionDecoratedFunction.php b/src/Reflection/ReflectionDecoratedFunction.php
new file mode 100644
index 0000000..cb8b628
--- /dev/null
+++ b/src/Reflection/ReflectionDecoratedFunction.php
@@ -0,0 +1,150 @@
+<?php
+/**
+ * Copyright 2018 Kacper Donat
+ *
+ * @author Kacper "Kadet" Donat <kacper@kadet.net>
+ *
+ * Full license available in separate LICENSE file
+ */
+
+namespace Kadet\Functional\Reflection;
+
+
+use function Kadet\Functional\reflect;
+
+class ReflectionDecoratedFunction extends \ReflectionFunction
+{
+    public $reflection;
+    public $decorated;
+
+    public function __construct(callable $decorated)
+    {
+        $this->decorated  = $decorated;
+        $this->reflection = reflect($decorated);
+    }
+
+    public function inNamespace()
+    {
+        return $this->reflection->inNamespace();
+    }
+
+    public function isClosure()
+    {
+        return $this->reflection->isVariadic();
+    }
+
+    public function isDeprecated()
+    {
+        return $this->reflection->isDeprecated();
+    }
+
+    public function isInternal()
+    {
+        return $this->reflection->isInternal();
+    }
+
+    public function isUserDefined()
+    {
+        return $this->reflection->isUserDefined();
+    }
+
+    public function getClosureThis()
+    {
+        return $this->reflection->getClosureThis();
+    }
+
+    public function getClosureScopeClass()
+    {
+        return $this->reflection->getClosureScopeClass();
+    }
+
+    public function getDocComment()
+    {
+        return $this->reflection->getDocComment();
+    }
+
+    public function getEndLine()
+    {
+        return $this->reflection->getEndLine();
+    }
+
+    public function getExtension()
+    {
+        return $this->reflection->getExtension();
+    }
+
+    public function getExtensionName()
+    {
+        return $this->reflection->getExtensionName();
+    }
+
+    public function getFileName()
+    {
+        return $this->reflection->getFileName();
+    }
+
+    public function getName()
+    {
+        return $this->reflection->getName();
+    }
+
+    public function getNamespaceName()
+    {
+        return $this->reflection->getNamespaceName();
+    }
+
+    public function getNumberOfParameters()
+    {
+        return $this->reflection->getNumberOfParameters();
+    }
+
+    public function getNumberOfRequiredParameters()
+    {
+        return $this->reflection->getNumberOfRequiredParameters();
+    }
+
+    public function getParameters()
+    {
+        return $this->reflection->getParameters();
+    }
+
+    public function getReturnType()
+    {
+        return $this->reflection->getReturnType();
+    }
+
+    public function getShortName()
+    {
+        return $this->reflection->getShortName();
+    }
+
+    public function getStartLine()
+    {
+        return $this->reflection->getStartLine();
+    }
+
+    public function getStaticVariables()
+    {
+        return $this->reflection->getStaticVariables();
+    }
+
+    public function hasReturnType()
+    {
+        return $this->reflection->hasReturnType();
+    }
+
+    public function returnsReference()
+    {
+        return $this->reflection->returnsReference();
+    }
+
+    public function isGenerator()
+    {
+        return $this->reflection->isGenerator();
+    }
+
+    public function isVariadic()
+    {
+        return $this->reflection->isVariadic();
+    }
+}
\ No newline at end of file
diff --git a/src/Reflection/ReflectionFixedFunction.php b/src/Reflection/ReflectionFixedFunction.php
index cc72f81..76bb455 100644
--- a/src/Reflection/ReflectionFixedFunction.php
+++ b/src/Reflection/ReflectionFixedFunction.php
@@ -12,7 +12,7 @@ namespace Kadet\Functional\Reflection;
 
 use Kadet\Functional\Utils\FixedFunction;
 
-class ReflectionFixedFunction extends \ReflectionFunction
+class ReflectionFixedFunction extends ReflectionDecoratedFunction
 {
     public function __construct(FixedFunction $function)
     {
diff --git a/src/Reflection/ReflectionPartiallyAppliedFunction.php b/src/Reflection/ReflectionPartiallyAppliedFunction.php
index c5b6162..164bb40 100644
--- a/src/Reflection/ReflectionPartiallyAppliedFunction.php
+++ b/src/Reflection/ReflectionPartiallyAppliedFunction.php
@@ -13,7 +13,7 @@ namespace Kadet\Functional\Reflection;
 use Kadet\Functional\Utils\CurriedFunction;
 use Kadet\Functional\Utils\PartiallyAppliedFunction;
 
-class ReflectionPartiallyAppliedFunction extends \ReflectionFunction
+class ReflectionPartiallyAppliedFunction extends ReflectionDecoratedFunction
 {
     public $applied;
 
diff --git a/src/Utils/FixedFunction.php b/src/Utils/FixedFunction.php
index e86582d..5cc38c9 100644
--- a/src/Utils/FixedFunction.php
+++ b/src/Utils/FixedFunction.php
@@ -32,7 +32,7 @@ class FixedFunction implements Decorator
 
     public function __invoke(...$args)
     {
-        return ($this->fixed)($this)(...$args);
+        return apply($this->fixed, $this, ...$args);
     }
 
     public function getDecorated()
diff --git a/src/Utils/index.php b/src/Utils/index.php
index ae82d71..df42adb 100644
--- a/src/Utils/index.php
+++ b/src/Utils/index.php
@@ -21,11 +21,29 @@ function partial(callable $callable, ...$args): PartiallyAppliedFunction
 
 function apply(callable $callable, ...$args)
 {
-    $threshold = reflect($callable)->getNumberOfRequiredParameters();
+    try {
+        $reflection = reflect($callable);
+        $required   = $reflection->getNumberOfRequiredParameters();
+        $all        = $reflection->getNumberOfParameters();
 
-    return count($args) >= $threshold
-        ? $callable(...$args)
-        : partial($callable, ...$args);
+        switch (true) {
+            case $reflection->isVariadic():
+                return partial($callable, ...$args);
+
+            case count($args) >= $all:
+                $applied = $callable(...array_slice($args, 0, $all));
+                return is_callable($applied) ? apply($applied, ...array_slice($args, $all)) : $applied;
+
+            case count($args) >= $required:
+                return $callable(...$args);
+
+            default:
+                return partial($callable, ...$args);
+        }
+    } catch (\ReflectionException $exception) {
+        // if cannot gather necessary information for intelligent application just use normal one
+        return $callable(...$args);
+    }
 }
 
 function curry(callable $callable, int $threshold = null, ...$args): CurriedFunction
diff --git a/src/functions.php b/src/functions.php
index d55ac99..6986946 100644
--- a/src/functions.php
+++ b/src/functions.php
@@ -6,7 +6,6 @@ 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;
@@ -71,7 +70,13 @@ function symbol($name = null)
     return sprintf("%s(%s)", $name ?: 'symbol', $id);
 }
 
-function reflect(callable $callable): \ReflectionFunctionAbstract
+/**
+ * @param callable $callable
+ *
+ * @return \ReflectionFunction
+ * @throws \ReflectionException
+ */
+function reflect(callable $callable): \ReflectionFunction
 {
     switch (true) {
         case $callable instanceof PartiallyAppliedFunction: