More format refactors

* module/ice-9/format.scm (format): Flatten all internal definitions,
  except format-work.

module/ice-9/format.scm

@@ -37,25 +37,25 @@
 (define format:version "3.0")
 
 (define (format destination format-string . format-args)
+  (define port
+    (begin
       (unless (string? format-string)
         (error "format: expected a string for format string" format-string))
 
-  (let* ((port
       (cond
        ((not destination) (open-output-string))
        ((boolean? destination) (current-output-port)) ; boolean but not false
        ((output-port? destination) destination)
        (else
-            (error "format: bad destination `~a'" destination))))
+        (error "format: bad destination `~a'" destination)))))
 
-         (output-col (or (port-column port) 0))
+  (define output-col (or (port-column port) 0))
 
-         (flush-output? #f))
+  (define flush-output? #f)
 
   (define format:case-conversion #f)
   (define format:pos 0)        ; curr. format string parsing position
   (define format:arg-pos 0)    ; curr. format argument position
-					; this is global for error presentation
 
   ;; format string and char output routines on port
 
@@ -1569,8 +1569,9 @@
 
   (define (format:abort) (error "error in format"))
 
-    (let ((arg-pos (format:format-work format-string format-args))
+  (define arg-pos (format:format-work format-string format-args))
-          (arg-len (length format-args)))
+  (define arg-len (length format-args))
+
   (cond
    ((> arg-pos arg-len)
     (set! format:arg-pos (+ arg-len 1))
@@ -1583,7 +1584,7 @@
         #t
         (let ((str (get-output-string port)))
           (close-port port)
-              str)))))))
+          str)))))
 
 ;; Thanks to Shuji Narazaki
 (module-set! the-root-module 'format format)