simplified using scheme control constructs

05-hydrothermal-venture/code.scm

@@ -44,13 +44,7 @@
 
 ; returns the largest value obtained while applying pick to each element of lst
 (define (get-max lst pick)
-  (let loop [(m 0)
-	     (lst lst)]
-    (if (null? lst)
-      m
-      [loop
-	(max m (pick (car lst)))
-	(cdr lst)])))
+  (apply max (map pick lst)))
 
 (define (sign value)
   (cond
@@ -95,10 +89,10 @@
   (let* [(width (+ 1 (get-max lines get-max-x)))
 	 (height (+ 1 (get-max lines get-max-y)))
 	 (image (make-image width height))]
-    (let loop! [(lines lines)]
-      (when (not (null? lines))
-	(additively-rasterize-line! image (car lines) allow-diagonals)
-	(loop! (cdr lines))))
+    (for-each
+      (lambda (line)
+	(additively-rasterize-line! image line allow-diagonals))
+      lines)
     image))
 
 ; count pixels with value strictly higher than 1