[functional tests] start a (loops) library

Contains upto.

functional-tests/loops.scm

@@ -0,0 +1,13 @@
+(library
+  (loops)
+  (export upto)
+  (import (rnrs))
+
+  (define-syntax upto
+    (syntax-rules ()
+      ((_ (var count) body ...)
+       (let loop ((var 0))
+         (when (< var count)
+             (begin body ...)
+             (loop (+ 1 var))))))))
+