diff --git a/application/Espo/Core/Formula/EvaluatedArgumentList.php b/application/Espo/Core/Formula/EvaluatedArgumentList.php
new file mode 100644
index 0000000000..91796c7b3b
--- /dev/null
+++ b/application/Espo/Core/Formula/EvaluatedArgumentList.php
@@ -0,0 +1,183 @@
+<?php
+/************************************************************************
+ * This file is part of EspoCRM.
+ *
+ * EspoCRM - Open Source CRM application.
+ * Copyright (C) 2014-2023 Yurii Kuznietsov, Taras Machyshyn, Oleksii Avramenko
+ * Website: https://www.espocrm.com
+ *
+ * EspoCRM is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * EspoCRM is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with EspoCRM. If not, see http://www.gnu.org/licenses/.
+ *
+ * The interactive user interfaces in modified source and object code versions
+ * of this program must display Appropriate Legal Notices, as required under
+ * Section 5 of the GNU General Public License version 3.
+ *
+ * In accordance with Section 7(b) of the GNU General Public License version 3,
+ * these Appropriate Legal Notices must retain the display of the "EspoCRM" word.
+ ************************************************************************/
+
+namespace Espo\Core\Formula;
+
+use BadMethodCallException;
+use OutOfBoundsException;
+use Iterator;
+use Countable;
+use ArrayAccess;
+use SeekableIterator;
+
+/**
+ * A list of evaluated function arguments.
+ *
+ * @implements ArrayAccess<int, mixed>
+ * @implements Iterator<mixed>
+ * @implements SeekableIterator<int, mixed>
+ */
+class EvaluatedArgumentList implements Iterator, Countable, ArrayAccess, SeekableIterator
+{
+    private int $position = 0;
+
+    /**
+     * @param mixed[] $dataList
+     */
+    public function __construct(private array $dataList)
+    {}
+
+    /**
+     * @return int
+     */
+    private function getLastValidKey()
+    {
+        $keys = array_keys($this->dataList);
+
+        $i = end($keys);
+
+        while ($i > 0) {
+            if (array_key_exists($i, $this->dataList)) {
+                break;
+            }
+
+            $i--;
+        }
+
+        return $i;
+    }
+
+    public function rewind(): void
+    {
+        $this->position = 0;
+
+        while (!$this->valid() && $this->position <= $this->getLastValidKey()) {
+            $this->position ++;
+        }
+    }
+
+    private function getArgumentByIndex(int $index): mixed
+    {
+        return $this->dataList[$index];
+    }
+
+    /**
+     * @return mixed
+     */
+    #[\ReturnTypeWillChange]
+    public function current()
+    {
+        return $this->getArgumentByIndex($this->position);
+    }
+
+    /**
+     * @return mixed
+     */
+    #[\ReturnTypeWillChange]
+    public function key()
+    {
+        return $this->position;
+    }
+
+    public function next(): void
+    {
+        do {
+            $this->position ++;
+            $next = false;
+
+            if (
+                !$this->valid() &&
+                $this->position <= $this->getLastValidKey()
+            ) {
+                $next = true;
+            }
+        } while ($next);
+    }
+
+    public function valid(): bool
+    {
+        return array_key_exists($this->position, $this->dataList);
+    }
+
+    /**
+     * @param mixed $offset
+     */
+    public function offsetExists($offset): bool
+    {
+        return array_key_exists($offset, $this->dataList);
+    }
+
+    /**
+     * @param mixed $offset
+     * @return mixed
+     */
+    #[\ReturnTypeWillChange]
+    public function offsetGet($offset)
+    {
+        if (!$this->offsetExists($offset)) {
+            return null;
+        }
+
+        return $this->getArgumentByIndex($offset);
+    }
+
+    /**
+     * @param mixed $offset
+     * @param mixed $value
+     */
+    public function offsetSet($offset, $value): void
+    {
+        throw new BadMethodCallException('Setting is not allowed.');
+    }
+
+    /**
+     * @param mixed $offset
+     */
+    public function offsetUnset($offset): void
+    {
+        throw new BadMethodCallException('Unsetting is not allowed.');
+    }
+
+    public function count(): int
+    {
+        return count($this->dataList);
+    }
+
+    /**
+     * @param int $offset
+     */
+    public function seek($offset): void
+    {
+        $this->position = $offset;
+
+        if (!$this->valid()) {
+            throw new OutOfBoundsException("Invalid seek offset ($offset).");
+        }
+    }
+}
diff --git a/application/Espo/Core/Formula/Evaluator.php b/application/Espo/Core/Formula/Evaluator.php
index a27be5b5e8..b317fa7f89 100644
--- a/application/Espo/Core/Formula/Evaluator.php
+++ b/application/Espo/Core/Formula/Evaluator.php
@@ -30,7 +30,10 @@
 namespace Espo\Core\Formula;
 
 use Espo\Core\Formula\Exceptions\Error;
+use Espo\Core\Formula\Exceptions\ExecutionException;
 use Espo\Core\Formula\Exceptions\SyntaxError;
+use Espo\Core\Formula\Functions\Base as DeprecatedBaseFunction;
+use Espo\Core\Formula\Functions\BaseFunction;
 use Espo\Core\Formula\Parser\Ast\Attribute;
 use Espo\Core\Formula\Parser\Ast\Node;
 use Espo\Core\Formula\Parser\Ast\Value;
@@ -45,32 +48,31 @@ use stdClass;
  */
 class Evaluator
 {
-    /** @var array<string, class-string> */
-    private $functionClassNameMap;
     private Parser $parser;
     private AttributeFetcher $attributeFetcher;
-    private InjectableFactory $injectableFactory;
     /** @var array<string, (Node|Value|Attribute|Variable)> */
     private $parsedHash;
 
     /**
-     * @param array<string, class-string> $functionClassNameMap
+     * @param array<string, class-string<BaseFunction|Func|DeprecatedBaseFunction>> $functionClassNameMap
      */
-    public function __construct(InjectableFactory $injectableFactory, array $functionClassNameMap = [])
-    {
+    public function __construct(
+        private InjectableFactory $injectableFactory,
+        private array $functionClassNameMap = []
+    ) {
         $this->attributeFetcher = $injectableFactory->create(AttributeFetcher::class);
-        $this->injectableFactory = $injectableFactory;
-        $this->functionClassNameMap = $functionClassNameMap;
         $this->parser = new Parser();
         $this->parsedHash = [];
     }
 
     /**
-     * @return mixed
+     * Process expression.
+     *
      * @throws SyntaxError
      * @throws Error
+     * @throws ExecutionException
      */
-    public function process(string $expression, ?Entity $entity = null, ?stdClass $variables = null)
+    public function process(string $expression, ?Entity $entity = null, ?stdClass $variables = null): mixed
     {
         $processor = new Processor(
             $this->injectableFactory,
@@ -81,9 +83,7 @@ class Evaluator
         );
 
         $item = $this->getParsedExpression($expression);
-
         $result = $processor->process($item);
-
         $this->attributeFetcher->resetRuntimeCache();
 
         return $result;
diff --git a/application/Espo/Core/Formula/Exceptions/BadArgumentType.php b/application/Espo/Core/Formula/Exceptions/BadArgumentType.php
index 8e9d59ea97..9cafe183c2 100644
--- a/application/Espo/Core/Formula/Exceptions/BadArgumentType.php
+++ b/application/Espo/Core/Formula/Exceptions/BadArgumentType.php
@@ -29,6 +29,34 @@
 
 namespace Espo\Core\Formula\Exceptions;
 
+/**
+ * A bad argument type.
+ */
 class BadArgumentType extends Error
 {
+    private ?int $position = null;
+    private ?string $type = null;
+
+    /**
+     * Create.
+     *
+     * @param int $position An argument position.
+     * @param string $type A required argument type.
+     */
+    public static function create(int $position, string $type): self
+    {
+        $obj = new self();
+        $obj->position = $position;
+        $obj->type = $type;
+
+        return $obj;
+    }
+
+    public function getLogMessage(): string
+    {
+        $position = (string) ($this->position ?? '?');
+        $type = $this->type ?? '?';
+
+        return "Bad argument type on position {$position}, must be {$type}.";
+    }
 }
diff --git a/application/Espo/Core/Formula/Exceptions/BadArgumentValue.php b/application/Espo/Core/Formula/Exceptions/BadArgumentValue.php
index 2d7f8fcf83..87181b3a58 100644
--- a/application/Espo/Core/Formula/Exceptions/BadArgumentValue.php
+++ b/application/Espo/Core/Formula/Exceptions/BadArgumentValue.php
@@ -29,6 +29,30 @@
 
 namespace Espo\Core\Formula\Exceptions;
 
+/**
+ * A bad argument value.
+ */
 class BadArgumentValue extends Error
 {
+    private ?int $position = null;
+
+    /**
+     * Create.
+     *
+     * @param int $position An argument position.
+     */
+    public static function create(int $position): self
+    {
+        $obj = new self();
+        $obj->position = $position;
+
+        return $obj;
+    }
+
+    public function getLogMessage(): string
+    {
+        $position = (string) ($this->position ?? '?');
+
+        return "Bad argument value on position {$position}.";
+    }
 }
diff --git a/application/Espo/Core/Formula/Exceptions/TooFewArguments.php b/application/Espo/Core/Formula/Exceptions/TooFewArguments.php
index 1496f3e508..60c811e8ce 100644
--- a/application/Espo/Core/Formula/Exceptions/TooFewArguments.php
+++ b/application/Espo/Core/Formula/Exceptions/TooFewArguments.php
@@ -29,6 +29,30 @@
 
 namespace Espo\Core\Formula\Exceptions;
 
+/**
+ * Too few function arguments passsed.
+ */
 class TooFewArguments extends Error
 {
+    private ?int $number = null;
+
+    /**
+     * Create.
+     *
+     * @param int $number A required number of arguments.
+     */
+    public static function create(int $number): self
+    {
+        $obj = new self();
+        $obj->number = $number;
+
+        return $obj;
+    }
+
+    public function getLogMessage(): string
+    {
+        $number = (string) ($this->number ?? '?');
+
+        return "Too few arguments passed, must be {$number}.";
+    }
 }
diff --git a/application/Espo/Core/Formula/Func.php b/application/Espo/Core/Formula/Func.php
new file mode 100644
index 0000000000..a60b92672f
--- /dev/null
+++ b/application/Espo/Core/Formula/Func.php
@@ -0,0 +1,46 @@
+<?php
+/************************************************************************
+ * This file is part of EspoCRM.
+ *
+ * EspoCRM - Open Source CRM application.
+ * Copyright (C) 2014-2023 Yurii Kuznietsov, Taras Machyshyn, Oleksii Avramenko
+ * Website: https://www.espocrm.com
+ *
+ * EspoCRM is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * EspoCRM is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with EspoCRM. If not, see http://www.gnu.org/licenses/.
+ *
+ * The interactive user interfaces in modified source and object code versions
+ * of this program must display Appropriate Legal Notices, as required under
+ * Section 5 of the GNU General Public License version 3.
+ *
+ * In accordance with Section 7(b) of the GNU General Public License version 3,
+ * these Appropriate Legal Notices must retain the display of the "EspoCRM" word.
+ ************************************************************************/
+
+namespace Espo\Core\Formula;
+
+use Espo\Core\Formula\Exceptions\Error;
+
+/**
+ * A function.
+ */
+interface Func
+{
+    /**
+     * Process.
+     *
+     * @param EvaluatedArgumentList $arguments
+     * @throws Error
+     */
+    public function process(EvaluatedArgumentList $arguments): mixed;
+}
diff --git a/application/Espo/Core/Formula/FunctionFactory.php b/application/Espo/Core/Formula/FunctionFactory.php
index 472b9fa0ec..ffd23887ee 100644
--- a/application/Espo/Core/Formula/FunctionFactory.php
+++ b/application/Espo/Core/Formula/FunctionFactory.php
@@ -36,36 +36,30 @@ use Espo\Core\Formula\Functions\BaseFunction;
 use Espo\ORM\Entity;
 use Espo\Core\InjectableFactory;
 
+use ReflectionClass;
 use stdClass;
 
 class FunctionFactory
 {
-    private Processor $processor;
-    private InjectableFactory $injectableFactory;
-    private AttributeFetcher $attributeFetcher;
-    /** @var array<string, class-string> */
+    /** @var array<string, class-string<BaseFunction|Func|Base>> */
     private $classNameMap;
 
     /**
-     * @param array<string,class-string> $classNameMap
+     * @param array<string, class-string<BaseFunction|Func|Base>> $classNameMap
      */
     public function __construct(
-        Processor $processor,
-        InjectableFactory $injectableFactory,
-        AttributeFetcher $attributeFetcher,
+        private Processor $processor,
+        private InjectableFactory $injectableFactory,
+        private AttributeFetcher $attributeFetcher,
         ?array $classNameMap = null
     ) {
-        $this->processor = $processor;
-        $this->injectableFactory = $injectableFactory;
-        $this->attributeFetcher = $attributeFetcher;
         $this->classNameMap = $classNameMap ?? [];
     }
 
     /**
-     * @return BaseFunction|Base
      * @throws UnknownFunction
      */
-    public function create(string $name, ?Entity $entity = null, ?stdClass $variables = null): object
+    public function create(string $name, ?Entity $entity = null, ?stdClass $variables = null): Func|BaseFunction|Base
     {
         if ($this->classNameMap && array_key_exists($name, $this->classNameMap)) {
             $className = $this->classNameMap[$name];
@@ -83,7 +77,7 @@ class FunctionFactory
 
             $typeName = implode('\\', $arr);
 
-            /** @var class-string<BaseFunction|Base> $className */
+            /** @var class-string<Func|BaseFunction|Base> $className */
             $className = 'Espo\\Core\\Formula\\Functions\\' . $typeName . 'Type';
         }
 
@@ -91,6 +85,10 @@ class FunctionFactory
             throw new UnknownFunction("Unknown function: " . $name);
         }
 
+        if ((new ReflectionClass($className))->implementsInterface(Func::class)) {
+            return $this->injectableFactory->create($className);
+        }
+
         $object = $this->injectableFactory->createWith($className, [
             'name' => $name,
             'processor' => $this->processor,
diff --git a/application/Espo/Core/Formula/Functions/BaseFunction.php b/application/Espo/Core/Formula/Functions/BaseFunction.php
index 83ce1c0307..f7e875eb97 100644
--- a/application/Espo/Core/Formula/Functions/BaseFunction.php
+++ b/application/Espo/Core/Formula/Functions/BaseFunction.php
@@ -163,7 +163,6 @@ abstract class BaseFunction
      * @throws Error
      */
     protected function throwError(?string $msg = null)
-
     {
         $string = 'function: ' . $this->name;
 
diff --git a/application/Espo/Core/Formula/Functions/StringGroup/ContainsType.php b/application/Espo/Core/Formula/Functions/StringGroup/ContainsType.php
index 48bbe48b86..5241f7f888 100644
--- a/application/Espo/Core/Formula/Functions/StringGroup/ContainsType.php
+++ b/application/Espo/Core/Formula/Functions/StringGroup/ContainsType.php
@@ -29,23 +29,20 @@
 
 namespace Espo\Core\Formula\Functions\StringGroup;
 
-use Espo\Core\Formula\{
-    Functions\BaseFunction,
-    ArgumentList,
-};
+use Espo\Core\Formula\EvaluatedArgumentList;
+use Espo\Core\Formula\Exceptions\TooFewArguments;
+use Espo\Core\Formula\Func;
 
-class ContainsType extends BaseFunction
+class ContainsType implements Func
 {
-    public function process(ArgumentList $args)
+    public function process(EvaluatedArgumentList $arguments): bool
     {
-        $args = $this->evaluate($args);
-
-        if (count($args) < 2) {
-            $this->throwTooFewArguments();
+        if (count($arguments) < 2) {
+            throw TooFewArguments::create(2);
         }
 
-        $string = $args[0];
-        $needle = $args[1];
+        $string = $arguments[0];
+        $needle = $arguments[1];
 
         if (!is_string($string)) {
             return false;
diff --git a/application/Espo/Core/Formula/Functions/UtilGroup/GenerateIdType.php b/application/Espo/Core/Formula/Functions/UtilGroup/GenerateIdType.php
index 3a46bd4c66..0dcbb712ac 100644
--- a/application/Espo/Core/Formula/Functions/UtilGroup/GenerateIdType.php
+++ b/application/Espo/Core/Formula/Functions/UtilGroup/GenerateIdType.php
@@ -29,18 +29,13 @@
 
 namespace Espo\Core\Formula\Functions\UtilGroup;
 
-use Espo\Core\Formula\{
-    ArgumentList,
-};
-
+use Espo\Core\Formula\EvaluatedArgumentList;
+use Espo\Core\Formula\Func;
 use Espo\Core\Utils\Util;
 
-class GenerateIdType
+class GenerateIdType implements Func
 {
-    /**
-     * @return string
-     */
-    public function process(ArgumentList $args)
+    public function process(EvaluatedArgumentList $arguments): string
     {
         return Util::generateId();
     }
diff --git a/application/Espo/Core/Formula/Processor.php b/application/Espo/Core/Formula/Processor.php
index b0e6121e30..b9b0274dbb 100644
--- a/application/Espo/Core/Formula/Processor.php
+++ b/application/Espo/Core/Formula/Processor.php
@@ -29,16 +29,20 @@
 
 namespace Espo\Core\Formula;
 
+use Espo\Core\Formula\Exceptions\BadArgumentType;
+use Espo\Core\Formula\Exceptions\BadArgumentValue;
 use Espo\Core\Formula\Exceptions\ExecutionException;
+use Espo\Core\Formula\Exceptions\TooFewArguments;
+use Espo\Core\Formula\Functions\Base as DeprecatedBaseFunction;
+use Espo\Core\Formula\Functions\BaseFunction;
 use Espo\Core\Formula\Parser\Ast\Attribute;
 use Espo\Core\Formula\Parser\Ast\Node;
 use Espo\Core\Formula\Parser\Ast\Value;
 use Espo\Core\Formula\Parser\Ast\Variable;
-use Espo\ORM\Entity;
-
 use Espo\Core\Formula\Exceptions\Error;
 use Espo\Core\InjectableFactory;
-use Espo\Core\Formula\Functions\Base as DeprecatedBaseFunction;
+
+use Espo\ORM\Entity;
 
 use InvalidArgumentException;
 use stdClass;
@@ -49,17 +53,16 @@ use stdClass;
 class Processor
 {
     private FunctionFactory $functionFactory;
-    private ?Entity $entity;
     private stdClass $variables;
 
     /**
-     * @param ?array<string, class-string> $functionClassNameMap
+     * @param ?array<string, class-string<BaseFunction|Func|DeprecatedBaseFunction>> $functionClassNameMap
      */
     public function __construct(
         InjectableFactory $injectableFactory,
         AttributeFetcher $attributeFetcher,
         ?array $functionClassNameMap = null,
-        ?Entity $entity = null,
+        private ?Entity $entity = null,
         ?stdClass $variables = null
     ) {
         $this->functionFactory = new FunctionFactory(
@@ -69,7 +72,6 @@ class Processor
             $functionClassNameMap
         );
 
-        $this->entity = $entity;
         $this->variables = $variables ?? (object) [];
     }
 
@@ -80,7 +82,7 @@ class Processor
      * @throws Error
      * @throws ExecutionException
      */
-    public function process(Evaluatable $item)
+    public function process(Evaluatable $item): mixed
     {
         if ($item instanceof ArgumentList) {
             return $this->processList($item);
@@ -92,7 +94,21 @@ class Processor
 
         $function = $this->functionFactory->create($item->getType(), $this->entity, $this->variables);
 
-        /** @deprecated */
+        if ($function instanceof Func) {
+            $evaluatedArguments = array_map(function ($item) {
+                return $this->process($item);
+            }, iterator_to_array($item->getArgumentList()));
+
+            try {
+                return $function->process(new EvaluatedArgumentList($evaluatedArguments));
+            }
+            catch (TooFewArguments|BadArgumentType|BadArgumentValue $e) {
+                $message = sprintf('Function %s; %s', $item->getType(), $e->getLogMessage());
+
+                throw new Error($message);
+            }
+        }
+
         if ($function instanceof DeprecatedBaseFunction) {
             return $function->process(self::dataToStdClass($item->getData()));
         }
@@ -139,6 +155,7 @@ class Processor
     /**
      * @return mixed[]
      * @throws Error
+     * @throws ExecutionException
      */
     private function processList(ArgumentList $args): array
     {
diff --git a/tests/unit/Espo/Core/Formula/EvaluatorTest.php b/tests/unit/Espo/Core/Formula/EvaluatorTest.php
index c91e9e5b6a..65634c2e48 100644
--- a/tests/unit/Espo/Core/Formula/EvaluatorTest.php
+++ b/tests/unit/Espo/Core/Formula/EvaluatorTest.php
@@ -30,6 +30,7 @@
 namespace tests\unit\Espo\Core\Formula;
 
 use Espo\Core\Formula\Evaluator;
+use Espo\Core\Formula\Exceptions\Error;
 use Espo\Core\InjectableFactory;
 use Espo\Core\Formula\Exceptions\SyntaxError;
 use Espo\Core\Utils\Log;
@@ -1153,4 +1154,31 @@ class EvaluatorTest extends \PHPUnit\Framework\TestCase
 
         $this->assertEquals(2, $value);
     }
+
+    public function testFuncInterface1(): void
+    {
+        $expression = "string\\contains(string\\concatenate('test', 'hello'), 'hello')";
+
+        $value = $this->evaluator->process($expression);
+
+        $this->assertEquals(true, $value);
+    }
+
+    public function testFuncInterface2(): void
+    {
+        $expression = "true == string\\contains('test hello', 'hello')";
+
+        $value = $this->evaluator->process($expression);
+
+        $this->assertEquals(true, $value);
+    }
+
+    public function testFuncInterfaceException(): void
+    {
+        $expression = "true == string\\contains('test hello')";
+
+        $this->expectException(Error::class);
+
+        $this->evaluator->process($expression);
+    }
 }