diff --git a/README.md b/README.md
index 68e0a15..05555d9 100644
--- a/README.md
+++ b/README.md
@@ -1,3 +1,3 @@
-# PhpArrayClass
+# PhpArrayClasses
 
 Classes for array embedding
\ No newline at end of file
diff --git a/composer.json b/composer.json
index 71a44b5..7e46304 100644
--- a/composer.json
+++ b/composer.json
@@ -1,5 +1,5 @@
 {
-    "name":              "jrosset/arrayclass",
+    "name":              "jrosset/arrayclasses",
     "description":       "Classes for array embedding",
     "keywords":          [ ],
 
diff --git a/src/ArrayClasses/ArrayClass.php b/src/ArrayClasses/ArrayClass.php
new file mode 100644
index 0000000..a32b610
--- /dev/null
+++ b/src/ArrayClasses/ArrayClass.php
@@ -0,0 +1,61 @@
+<?php
+
+namespace jrosset\ArrayClasses;
+
+use OutOfRangeException;
+
+/**
+ * An array
+ */
+class ArrayClass extends ImmutableArrayClass {
+    /**
+     * Set or replace a cell value
+     *
+     * @param mixed $offset The cell offset
+     * @param mixed $value  The cell new value
+     *
+     * @return $this
+     */
+    public function set ($offset, $value): self {
+        $this->array[$offset] = $value;
+        return $this;
+    }
+    /**
+     * Remove a cell
+     *
+     * @param mixed     $offset                      The cell offset
+     * @param bool|null $throwsForNonExistentElement If set, temporarily override {@see ImmutableArrayClass::$throwsForNonExistentElement}
+     *
+     * @return $this
+     */
+    public function del ($offset, ?bool $throwsForNonExistentElement = null): self {
+        if ($throwsForNonExistentElement ?? $this->throwsForNonExistentElement() && !$this->has($offset)) {
+            throw new OutOfRangeException();
+        }
+        unset($this->array[$offset]);
+
+        return $this;
+    }
+
+    /**
+     * Create an immutable copy
+     *
+     * @return ImmutableArrayClass The immutable copy
+     */
+    public function toImmutableArrayClass (): ImmutableArrayClass {
+        return new ImmutableArrayClass($this);
+    }
+
+    /**
+     * @inheritDoc
+     */
+    public function offsetSet ($offset, $value): void {
+        $this->set($offset, $value);
+    }
+    /**
+     * @inheritDoc
+     */
+    public function offsetUnset ($offset): void {
+        $this->del($offset);
+    }
+}
\ No newline at end of file
diff --git a/src/ArrayClasses/IArrayCast.php b/src/ArrayClasses/IArrayCast.php
new file mode 100644
index 0000000..6057ed4
--- /dev/null
+++ b/src/ArrayClasses/IArrayCast.php
@@ -0,0 +1,15 @@
+<?php
+
+namespace jrosset\ArrayClasses;
+
+/**
+ * Interface for PHP-native array cast
+ */
+interface IArrayCast {
+    /**
+     * Transform to a PHP-native array
+     *
+     * @return array The native array
+     */
+    public function toArray (): array;
+}
\ No newline at end of file
diff --git a/src/ArrayClasses/ImmutableArrayClass.php b/src/ArrayClasses/ImmutableArrayClass.php
new file mode 100644
index 0000000..780d952
--- /dev/null
+++ b/src/ArrayClasses/ImmutableArrayClass.php
@@ -0,0 +1,182 @@
+<?php
+
+namespace jrosset\ArrayClasses;
+
+use ArrayAccess;
+use ArrayIterator;
+use Countable;
+use InvalidArgumentException;
+use IteratorAggregate;
+use JsonSerializable;
+use OutOfRangeException;
+use Serializable;
+use Traversable;
+
+/**
+ * An immutable array
+ */
+class ImmutableArrayClass implements IteratorAggregate, JsonSerializable, Serializable, Countable, ArrayAccess, IArrayCast {
+    /**
+     * @var array The internal array
+     */
+    protected array $array;
+    /**
+     * @var bool Throws an exception for nonexistent elements ?
+     */
+    private bool $throwsForNonExistentElement;
+
+    /**
+     * Initialize the array
+     *
+     * @param IArrayCast|array|null $initial                     The initial value
+     * @param bool                  $throwsForNonExistentElement Throws an exception for nonexistent elements ?
+     */
+    public function __construct ($initial = null, bool $throwsForNonExistentElement = true) {
+        $this->setThrowsForNonExistentElement($throwsForNonExistentElement);
+
+        if (is_array($initial)) {
+            $this->array = $initial;
+        }
+        elseif (is_null($initial)) {
+            $this->array = [];
+        }
+        elseif ($initial instanceof IArrayCast) {
+            $this->array = $initial->toArray();
+        }
+        else {
+            throw new InvalidArgumentException('The initial value is not valid: null, array or ' . IArrayCast::class);
+        }
+    }
+    /**
+     * Get the value of a cell
+     *
+     * @param mixed $offset The cell offset
+     *
+     * @return mixed|null The cell value
+     */
+    public function __invoke ($offset) {
+        return $this->get($offset);
+    }
+
+    /**
+     * Check if a cell offset exists
+     *
+     * @param mixed $offset The cell offset
+     *
+     * @return bool True if the cell offset exists
+     */
+    public function has ($offset): bool {
+        return array_key_exists($offset, $this->array);
+    }
+    /**
+     * Get the value of a cell
+     *
+     * @param mixed     $offset                      The cell offset
+     * @param bool|null $throwsForNonExistentElement If set, temporarily override {@see ImmutableArrayClass::$throwsForNonExistentElement}
+     *
+     * @return mixed|null The cell value
+     */
+    public function get ($offset, ?bool $throwsForNonExistentElement = null) {
+        if ($this->has($offset)) {
+            return $this->array[$offset];
+        }
+        if ($throwsForNonExistentElement ?? $this->throwsForNonExistentElement()) {
+            throw new OutOfRangeException();
+        }
+        return null;
+    }
+
+    /**
+     * @inheritDoc
+     */
+    public function toArray (): array {
+        return $this->array;
+    }
+    /**
+     * Create a mutable copy
+     *
+     * @return ArrayClass The mutable copy
+     */
+    public function toMutableArrayClass (): ArrayClass {
+        return new ArrayClass($this);
+    }
+
+    /**
+     * @inheritDoc
+     */
+    public function count (): int {
+        return count($this->array);
+    }
+
+    /**
+     * @inheritDoc
+     */
+    public function getIterator (): Traversable {
+        return new ArrayIterator($this->array);
+    }
+
+    /**
+     * @inheritDoc
+     */
+    public function offsetExists ($offset): bool {
+        return $this->has($offset);
+    }
+    /**
+     * @inheritDoc
+     */
+    public function offsetGet ($offset) {
+        return $this->get($offset);
+    }
+    /**
+     * @inheritDoc
+     */
+    public function offsetSet ($offset, $value): void {
+        throw new ImmutableException();
+    }
+    /**
+     * @inheritDoc
+     */
+    public function offsetUnset ($offset): void {
+        throw new ImmutableException();
+    }
+
+    /**
+     * @inheritDoc
+     */
+    public function serialize (): string {
+        return serialize($this->array);
+    }
+    /**
+     * @inheritDoc
+     */
+    public function unserialize ($data): void {
+        $this->array = unserialize($data);
+    }
+
+    /**
+     * @inheritDoc
+     */
+    public function jsonSerialize () {
+        return $this->array;
+    }
+
+    /**
+     * Throws an exception for nonexistent elements ?
+     *
+     * @return bool Throws an exception for nonexistent elements ?
+     */
+    public function throwsForNonExistentElement (): bool {
+        return $this->throwsForNonExistentElement;
+    }
+    /**
+     * Set if throws an exception for nonexistent elements
+     *
+     * @param bool $throwsForNonExistentElement Throws an exception for nonexistent elements ?
+     *
+     * @return $this
+     */
+    public function setThrowsForNonExistentElement (bool $throwsForNonExistentElement): self {
+        $this->throwsForNonExistentElement = $throwsForNonExistentElement;
+        return $this;
+    }
+}
\ No newline at end of file
diff --git a/src/ArrayClasses/ImmutableException.php b/src/ArrayClasses/ImmutableException.php
new file mode 100644
index 0000000..8f7dfb9
--- /dev/null
+++ b/src/ArrayClasses/ImmutableException.php
@@ -0,0 +1,11 @@
+<?php
+
+namespace jrosset\ArrayClasses;
+
+use LogicException;
+
+/**
+ * Exception thrown when trying to modify an immutable element
+ */
+class ImmutableException extends LogicException {
+}
\ No newline at end of file