add function: exit

README.md

@@ -144,6 +144,7 @@ doc   | `(doc +)` | `"Return the sum of all arguments."` | Show description of a
 read  | `(read "(+ 1 2 3)")` | `(+ 1 2 3)` | Read a string as code and return the expression.
 print | `(print "hello world")` | `"hello world"null` | Print expression on the screen. Print returns null (which is shown due to the extra print in repl). Give optional second argument as `true` to show strings in readable format.
 error | `(error "invalid value")` | `error: invalid value` | Throw an exception with message as argument.
+exit  | `(exit 1)` | | Terminate the script with given exit code using [exit](https://www.php.net/manual/en/function.exit.php).
 
 ### Collection functions
 

src/LispFactory.php

@@ -41,6 +41,12 @@ class LispFactory
             }
         ));
 
+        $env->set('exit', new CoreFunc('exit', 'Terminate the script with given exit code.', 0, 1,
+            function ($status = 0) {
+                exit($status);
+            }
+        ));
+
         // Register core libraries
         (new Lib\Collections())->register($env);
         (new Lib\Compare())->register($env);