Easy Digital Downloads - redirect when cart is empty

gistfile1.php

<?php

function sumobi_edd_empty_cart_redirect() {
	$cart 		= function_exists( 'edd_get_cart_contents' ) ? edd_get_cart_contents() : false;
	$redirect 	= site_url( 'shop' ); // could be the URL to your shop

	if ( function_exists( 'edd_is_checkout' ) && edd_is_checkout() && ! $cart ) {
		wp_redirect( $redirect, 301 ); 
		exit;
	}
}
add_action( 'template_redirect', 'sumobi_edd_empty_cart_redirect' );