Minor improvement to ports test runner and adds pure Scheme string-index

Author: codeZeilen

ports/ports.scm

@@ -294,7 +294,7 @@
             (define (display-test-result-details test-results info)
                 (for-each 
                         (lambda (test-result)
-                            (display "- " (string-append (test-full-name (test-result-test test-result)) "\n"))
+                            (display (string-append "- " (test-full-name (test-result-test test-result)) "\n"))
                             (display (info test-result))
                             (display "\n"))
                         test-results))

ports/stdlib.scm

@@ -167,5 +167,12 @@
 
     (define (string-prefix-ci? prefix string)
         (string-prefix? (string-downcase prefix) (string-downcase string)))
+
+    (define (string-index str substr)
+        (define (string-index-help str substr index)
+            (if (empty? str) #f
+                (if (string-prefix? substr str) index
+                    (string-index-help (cdr str) substr (+ index 1)))))
+        (string-index-help str substr 0))
 
 )