Replace 'when' and 'unless'.

1 files changed, 10 insertions, 10 deletions

diff --git a/module/util/tree.scm b/module/util/tree.scm
index 8d3e7805..474dc272 100644
--- a/module/util/tree.scm
+++ b/module/util/tree.scm
@@ -11,12 +11,12 @@
 ;; Has thee form @var{(node left-subtree right-subtree)}. A leaf has
 ;; both it's children equal to @var{null}.
 (define (make-tree pred? lst)
-  (if (null? lst) '()
-      (let* ((head tail (partition (lambda (el) (pred? (car lst) el))
-                                   (cdr lst))))
-        (list (car lst)
-              (make-tree pred? head)
-              (make-tree pred? tail)))))
+  (unless (null? lst)
+    (let* ((head tail (partition (lambda (el) (pred? (car lst) el))
+                                 (cdr lst))))
+      (list (car lst)
+            (make-tree pred? head)
+            (make-tree pred? tail)))))
 
 (define (left-subtree tree)
   (list-ref tree 1))
@@ -34,7 +34,7 @@
              (length-of-longst-branch (right-subtree tree)))))
 
 (define (tree-map proc tree)
-  (if (null? tree) '()
-      (list (proc (car tree))
-            (tree-map proc (left-subtree tree))
-            (tree-map proc (right-subtree tree)))))
+  (unless (null? tree)
+    (list (proc (car tree))
+          (tree-map proc (left-subtree tree))
+          (tree-map proc (right-subtree tree)))))