diff --git a/api.php b/api.php
new file mode 100644
index 0000000..8a0aed6
--- /dev/null
+++ b/api.php
@@ -0,0 +1,34 @@
+<?php
+
+namespace Checker {
+trait Scalar {
+    function isString() {
+    }
+}
+}
+
+namespace {
+
+class Parameter
+{
+    use Checker\Scalar;
+}
+
+
+$phone = new Parameter('phone', '0648099915');
+
+
+if ('0648099915' === $Parameter->value()) {
+    echo '1';
+}
+
+if (true === $Parameter->isValid()) {
+    echo '2';
+}
+
+$Parameters = new Parameters(['name' => 'pierre', 'phone', '0648099915']);
+
+true === $Parameters->isValid();
+//[...] === $Parameters->values();
+
+}
diff --git a/composer.json b/composer.json
new file mode 100644
index 0000000..e69de29
diff --git a/src/Checker/Scalar.php b/src/Checker/Scalar.php
new file mode 100644
index 0000000..7025341
--- /dev/null
+++ b/src/Checker/Scalar.php
@@ -0,0 +1,16 @@
+<?php
+
+namespace Plab\Parameter\Checker;
+
+trait Scalar
+{
+    public function isString($value)
+    {
+        return is_string($value);
+    }
+
+    public function isBoolean($value)
+    {
+        return is_bool($value);
+    }
+}
diff --git a/src/Converter/Scalar.php b/src/Converter/Scalar.php
new file mode 100644
index 0000000..1608316
--- /dev/null
+++ b/src/Converter/Scalar.php
@@ -0,0 +1,24 @@
+<?php
+
+namespace Plab\Parameter\Converter;
+
+trait Scalar
+{
+    public function toString($value) : string
+    {
+        return '' . $value;
+    }
+
+    public function toBoolean($value) : bool
+    {
+        if ('true' === $value || 1 === $value || 'on' === $value) {
+            return true;
+        }
+
+        if ('false' === $value || 0 === $value || 'off' === $value) {
+            return false;
+        }
+
+        return (bool)($value);
+    }
+}
diff --git a/src/Parameter.php b/src/Parameter.php
new file mode 100644
index 0000000..6fc0b8d
--- /dev/null
+++ b/src/Parameter.php
@@ -0,0 +1,56 @@
+<?php
+
+namespace Plab\Parameter;
+
+abstract class Parameter
+{
+    protected $key;
+    protected $value;
+
+    /**
+     * Map assertions callback, must be pure method
+     * @param $key
+     * @return string
+     */
+    abstract protected function mapAssertion($key) : string;
+
+    /**
+     * Return true if parameter must be readonly and not edited from user space
+     * @param $key
+     * @return bool
+     */
+    abstract protected function isReadOnly($key) : boolean;
+
+    /**
+     * Map converter callback, must be pure method
+     * @param $key
+     * @return string
+     */
+    abstract protected function mapConverter($key) : string;
+
+    public function __construct($key, $value)
+    {
+        $this->key = $key;
+        $this->value = $value;
+    }
+
+    public function isValid()
+    {
+        $checker = $this->mapAssertion($this->key);
+
+        if (null === $checker) {
+            //TODO assertion missing for this parameter
+        }
+    }
+
+    public function value()
+    {
+        $conveter = $this->mapConverter($this->key);
+
+        if (null === $converter) {
+            return $this->value;
+        }
+
+        //TODO call converter
+    }
+}
diff --git a/src/Parameters.php b/src/Parameters.php
new file mode 100644
index 0000000..411eeed
--- /dev/null
+++ b/src/Parameters.php
@@ -0,0 +1,40 @@
+<?php
+
+namespace Plab\Parameter;
+
+class Parameters implements Iterator
+{
+    protected $iterator = [];
+
+    public function __construct(Iterator $parameters)
+    {
+
+        foreach ($parameters as $key => $value) {
+
+            if ($value instanceof Parameter) {
+                $this->iterator = $value;
+                continue;
+            }
+            
+            $this->iterator[] = new Parameter($key, $value);
+        }
+    }
+
+    public function isValid()
+    {
+        foreach ($this->iterator as $parameter) {
+            //TODO we dont need stop if we want group hoa exception
+        }
+    }
+
+    public function values()
+    {
+        $result = [];
+
+        foreach ($this->iterator as $parameter) {
+            $result[$parameter->key()] = $parameter->value();
+        }
+
+        return $result;
+    }
+}