<?php

$router = new Simple_REST_API\Router( 'my-plugin/v1' );

$router->get( '/posts', function() {
    return get_posts();
} );

$router->get( '/post/{id}', function( $response, $id ) {
    $post = get_post( $id );
    if( ! $post ) {
        $response->set_status( 404 );
    }
    else {
        $response->set_data( $post );
    }
    return $response;
} );