diff options
Diffstat (limited to 'module/util.scm')
| -rw-r--r-- | module/util.scm | 9 |
1 files changed, 8 insertions, 1 deletions
diff --git a/module/util.scm b/module/util.scm index c7535310..bb1fdcd5 100644 --- a/module/util.scm +++ b/module/util.scm @@ -416,13 +416,20 @@ ;; Returns the cross product between l1 and l2. ;; each element is a cons cell. -(define-public (cross-product l1 l2) +(define (cross-product% l1 l2) (concatenate (map (lambda (a) (map (lambda (b) (cons a b)) l2)) l1))) +(define-public (cross-product . args) + (if (null? args) + '() + (let* ((last rest (car+cdr (reverse args)))) + (reduce-right cross-product% '() + (reverse (cons (map list last) rest )))))) + ;; Given an arbitary tree, do a pre-order traversal, appending all strings. ;; non-strings allso allowed, converted to strings and also appended. (define-public (string-flatten tree) |