From debda2e60260ae16f5be1549a59652e4de1039a3 Mon Sep 17 00:00:00 2001
From: Pekka Laiho <pekka.i.laiho@gmail.com>
Date: Sat, 30 May 2020 19:19:37 +0700
Subject: [PATCH] add do

---
 bootstrap.php   |  5 +++++
 src/Evaller.php | 10 ++++++++++
 2 files changed, 15 insertions(+)

diff --git a/bootstrap.php b/bootstrap.php
index 1a30955..8f0e37d 100644
--- a/bootstrap.php
+++ b/bootstrap.php
@@ -22,5 +22,10 @@ function ml_get_lisp(): array
         return $results[count($results) - 1];
     });
 
+    $env->set('print', function (...$args) use ($printer) {
+        $printer->print($args);
+        return null;
+    });
+
     return [$lisp, $env];
 }
diff --git a/src/Evaller.php b/src/Evaller.php
index 727a3dc..aad14b9 100644
--- a/src/Evaller.php
+++ b/src/Evaller.php
@@ -60,6 +60,16 @@ class Evaller
 
                 $value = $this->doEval($ast->get(2), $env);
                 return $env->set($ast->get(1)->getName(), $value);
+            } elseif ($ast->get(0)->getName() == 'do') {
+                if ($ast->count() < 2) {
+                    throw new MadLispException("do requires at least 1 argument");
+                }
+
+                for ($i = 1; $i < $ast->count(); $i++) {
+                    $value = $this->evalAst($ast->get($i), $env);
+                }
+
+                return $value;
             } elseif ($ast->get(0)->getName() == 'if') {
                 if ($ast->count() < 3 || $ast->count() > 4) {
                     throw new MadLispException("if requires 2 or 3 arguments");