>From fe97ba69a041c34c2d98a24baca03617f26c1df4 Mon Sep 17 00:00:00 2001
From: Peter Bex <address@hidden>
Date: Sun, 26 May 2013 19:38:17 +0200
Subject: [PATCH 1/2] Added #\null and #\escape character literal names, for
 R7RS compatibility.

WRITE now uses this instead of the old #\nul and #\esc, so other impls
can READ s-expression written by CHICKEN.  Unfortunately, the flip side
is that older CHICKENs can't READ data written by newer CHICKENs.
---
 NEWS                 |  2 ++
 library.scm          |  4 ++++
 tests/r7rs-tests.scm | 23 +++++++++++++++++++++++
 3 files changed, 29 insertions(+)

diff --git a/NEWS b/NEWS
index 07a8a5a..f2d28fc 100644
--- a/NEWS
+++ b/NEWS
@@ -22,6 +22,8 @@
     and "#!rest" in type-declarations (suggested by Joerg Wittenberger).
   - Vectors, SRFI-4 number vectors and blobs are now self-evaluating for
      R7RS compatibility.  Being literal constants, they are implicitly quoted.
+  - For R7RS compatibility, named character literals #\escape and #\null are
+     supported as aliases for #\esc and #\nul.  WRITE will output R7RS names.
 
 - Compiler
   - the "inline" declaration does not force inlining anymore as recursive
diff --git a/library.scm b/library.scm
index f42ddd7..cd33b09 100644
--- a/library.scm
+++ b/library.scm
@@ -1527,6 +1527,8 @@ EOF
 	       (and-let* ([a (assq x names-to-chars)])
 		 (##sys#slot a 1) ) ] ) ) ) ) )
 
+;; TODO: Use the character names here in the next release?  Or just
+;; use the numbers everywhere, for clarity?
 (char-name 'space #\space)
 (char-name 'tab #\tab)
 (char-name 'linefeed #\linefeed)
@@ -1534,8 +1536,10 @@ EOF
 (char-name 'vtab (integer->char 11))
 (char-name 'delete (integer->char 127))
 (char-name 'esc (integer->char 27))
+(char-name 'escape (integer->char 27))
 (char-name 'alarm (integer->char 7))
 (char-name 'nul (integer->char 0))
+(char-name 'null (integer->char 0))
 (char-name 'return #\return)
 (char-name 'page (integer->char 12))
 (char-name 'backspace (integer->char 8))
diff --git a/tests/r7rs-tests.scm b/tests/r7rs-tests.scm
index bc21294..368f9f4 100644
--- a/tests/r7rs-tests.scm
+++ b/tests/r7rs-tests.scm
@@ -71,6 +71,29 @@
 
 
 
+(SECTION 6 6)
+
+
+(define (integer->named-char x)
+  (with-output-to-string (lambda () (write (integer->char x)))))
+
+(test "#\\alarm" integer->named-char #x07)
+(test "#\\backspace" integer->named-char #x08)
+(test "#\\delete" integer->named-char #x7f)
+(test "#\\escape" integer->named-char #x1b)
+(test "#\\newline" integer->named-char #x0a)
+(test "#\\null" integer->named-char #x00)
+(test "#\\return" integer->named-char #x0d)
+(test "#\\space" integer->named-char #x20)
+(test "#\\tab" integer->named-char #x09)
+
+
+
+;; NOT YET (is ambiguous with existing \xNN syntax in Chicken)
+#;(test #\tab escaped-char "x9;")
+#;(test #\tab escaped-char "x09;")
+
+
 (SECTION 6 8)
 
 ;; Symbols are implicitly quoted inside self-evaluating vectors.
-- 
1.8.2.3