From 9543962ece4671f0f53c85ef9728d1188e86f0a3 Mon Sep 17 00:00:00 2001
From: Jan Nieuwenhuizen <janneke@gnu.org>
Date: Sun, 11 Nov 2018 10:10:43 +0100
Subject: [PATCH] mes: Add char-downcase, char-upcase.

* mes/module/srfi/srfi-14.mes (char-downcase, char-upcase): New
function.
---
 mes/module/srfi/srfi-14.mes | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/mes/module/srfi/srfi-14.mes b/mes/module/srfi/srfi-14.mes
index a0a96b92..2e925ec5 100644
--- a/mes/module/srfi/srfi-14.mes
+++ b/mes/module/srfi/srfi-14.mes
@@ -76,3 +76,15 @@
 
 (define (char-set-copy cs)
   (map identity cs))
+
+(define (char-upcase c)
+  (if (char-set-contains? char-set:lower-case c) (integer->char (- (char->integer c)
+                                                                   (- (char->integer #\a)
+                                                                      (char->integer #\A))))
+      c))
+
+(define (char-downcase c)
+  (if (char-set-contains? char-set:upper-case c) (integer->char (+ (char->integer c)
+                                                                   (- (char->integer #\a)
+                                                                      (char->integer #\A))))
+      c))