diff options
| -rw-r--r-- | net/ricketyspace/sicp/two/thirtynine.scm | 22 |
1 files changed, 22 insertions, 0 deletions
diff --git a/net/ricketyspace/sicp/two/thirtynine.scm b/net/ricketyspace/sicp/two/thirtynine.scm new file mode 100644 index 0000000..8c05587 --- /dev/null +++ b/net/ricketyspace/sicp/two/thirtynine.scm @@ -0,0 +1,22 @@ +;;;; License: CC0-1.0 + +(define-module (net ricketyspace sicp two thirtynine) + #:use-module (net ricketyspace sicp two thirtyeight) + #:export (reverse-fr + reverse-fl)) + +(define (reverse-fr sequence) + (fold-right (lambda (x y) (append y (list x))) '() sequence)) + +(define (reverse-fl sequence) + (fold-left (lambda (x y) (append (list y) x)) '() sequence)) + +;;; +;;; Guile REPL +;;; +;;; scheme@(guile-user)> ,re (net ricketyspace sicp two thirtynine) +;;; scheme@(guile-user)> (reverse-fr '(1 2 3 4 5 6)) +;;; $8 = (6 5 4 3 2 1) +;;; scheme@(guile-user)> (reverse-fl '(1 2 3 4 5 6)) +;;; $9 = (6 5 4 3 2 1) +;;; |