Changing sleep to accept (Rational :a) types

library/system.lisp

@@ -3,6 +3,9 @@
    #:coalton
    #:coalton-library/builtin
    #:coalton-library/classes)
+  (:local-nicknames
+   (#:arith #:coalton-library/math/arith)
+   (#:real  #:coalton-library/math/real))
   (:export
    #:gc
    #:time
@@ -61,12 +64,15 @@ While the result will always contain microseconds, some implementations may retu
                (cl:* 1000000 (cl:- end start))
                cl:internal-time-units-per-second)))))
 
-  (declare sleep (Integer -> Unit))
+  (declare sleep ((real:Rational :a) => :a -> Unit))
   (define (sleep n)
     "Sleep for `n` seconds."
-    (lisp Unit (n)
-      (cl:sleep n)
-      Unit)))
+    (if (arith:negative? n)
+        (error "must be a positive number.")
+        (let ((frac (real:best-approx n)))
+          (lisp Unit (frac)
+            (cl:sleep frac)
+            Unit)))))
 
 ;;;
 ;;; Pofiling