Add (net ricketyspace sicp two twentyeight).

* net/ricketyspace/sicp/two/twentyeight.scm: New file.

1 files changed, 21 insertions, 0 deletions

diff --git a/net/ricketyspace/sicp/two/twentyeight.scm b/net/ricketyspace/sicp/two/twentyeight.scm
new file mode 100644
index 0000000..dbba0e0
--- /dev/null
+++ b/net/ricketyspace/sicp/two/twentyeight.scm
@@ -0,0 +1,21 @@
+;;;; License: CC0-1.0
+
+(define-module (net ricketyspace sicp two twentyeight)
+  #:export (fringe))
+
+(define (fringe x)
+  (cond ((null? x) '())
+        ((not (pair? x)) (list x))
+        (else (append (fringe (car x))
+                      (fringe (cdr x))))))
+
+
+;;; Guile REPL
+
+;;; scheme@(guile-user)> ,use (net ricketyspace sicp two twentyeight)
+;;; scheme@(guile-user)> (define x (list (list 1 2) (list 3 4)))
+;;;
+;;; scheme@(guile-user)> (fringe x)
+;;; $12 = (1 2 3 4)
+;;; scheme@(guile-user)> (fringe (list x x))
+;;; $13 = (1 2 3 4 1 2 3 4)