Use format egg to pad comic numbers

README.md

@@ -1,7 +1,7 @@
 # Dependencies
 
 - [CHICKEN Scheme](https://call-cc.org) 5 or 6;
-- A few CHICKEN extensions, installable using `chicken-install -s html-parser openssl http-client matchable srfi-18`.
+- A few CHICKEN extensions, installable using `chicken-install -s format html-parser openssl http-client matchable srfi-18`.
 
 # Building
 

rain.scm

@@ -11,7 +11,7 @@
 
 (define (download-comic-image index)
   (format (current-error-port) "* downloading comic image ~a~%" index)
-  (call-with-output-file (format #f "rain-~a.png" index)
+  (call-with-output-file (format #f "rain-~4,48,d.png" (string->number index))
     (lambda (out)
       (call-with-input-request (find-comic-image index)
                                #f

rain.sld

@@ -8,9 +8,9 @@ exec csi -s "$0" "$@"
    (scheme file)
    (chicken base)
    (chicken io)
-   (chicken format)
    (chicken port)
    (chicken process-context)
+   (format)
    (html-parser)
    (openssl)                            ; has to be before http-client
    (http-client)