Change string-map to use string-builder.

diff --git a/src/runtime/ustring.scm b/src/runtime/ustring.scm
index 1f568f9b94692e824a4157ddbbb372b4e337551a..4a5ebed926b7be73efdb0992b718981187a750c6 100644 (file)
--- a/src/runtime/ustring.scm
+++ b/src/runtime/ustring.scm
@@ -1039,11 +1039,11 @@ USA.
 
 (define (string-map proc string . strings)
   (receive (n proc) (mapper-values proc string strings)
-    (let ((result (full-string-allocate n)))
+    (let ((builder (string-builder)))
       (do ((i 0 (fix:+ i 1)))
          ((not (fix:< i n)))
-       (%full-string-set! result i (proc i)))
-      result)))
+       (builder (proc i)))
+      (builder))))
 
 (define (string-count proc string . strings)
   (receive (n proc) (mapper-values proc string strings)