From 96a90810afdb6c4d642ec522cabb3e369a4b0919 Mon Sep 17 00:00:00 2001
From: Yuichi Nishiwaki <yuichi.nishiwaki@gmail.com>
Date: Sun, 31 Aug 2014 01:41:12 +0900
Subject: [PATCH] import (picrin readline) only when exists

---
 contrib/20.repl/repl.scm | 19 +++++++++++++++++--
 1 file changed, 17 insertions(+), 2 deletions(-)

diff --git a/contrib/20.repl/repl.scm b/contrib/20.repl/repl.scm
index 010212ac..d2064c8f 100644
--- a/contrib/20.repl/repl.scm
+++ b/contrib/20.repl/repl.scm
@@ -3,8 +3,23 @@
           (scheme read)
           (scheme write)
           (scheme eval)
-          (picrin readline)
-          (picrin readline history))
+          (picrin macro)
+          (picrin library))
+
+  (define-syntax define-readline
+    (er-macro-transformer
+     (lambda (form rename compare)
+       (if (member '(picrin readline) (libraries))
+           `(import (picrin readline)
+                    (picrin readline history))
+           `(begin
+              (define (readline str)
+                (display str)
+                (read-line))
+              (define (add-history str)
+                #f))))))
+
+  (define-readline)
 
   (define (repl)
     (let ((line (readline "> ")))