diff options
| -rw-r--r-- | net/ricketyspace/sicp/two/thirtytwo.scm | 16 |
1 files changed, 16 insertions, 0 deletions
diff --git a/net/ricketyspace/sicp/two/thirtytwo.scm b/net/ricketyspace/sicp/two/thirtytwo.scm new file mode 100644 index 0000000..31d6446 --- /dev/null +++ b/net/ricketyspace/sicp/two/thirtytwo.scm @@ -0,0 +1,16 @@ +;;;; License: CC0-1.0 + +(define-module (net ricketyspace sicp two thirtytwo) + #:export (subsets)) + +(define (subsets s) + (if (null? s) + (list '()) + (let ((rest (subsets (cdr s)))) + (append rest (map (lambda (item) (cons (car s) item)) rest))))) + +;;; Guile REPL +;;; +;;; scheme@(guile-user)> ,use (net ricketyspace sicp two thirtytwo) +;;; scheme@(guile-user)> (subsets '(1 2 3)) +;;; $6 = (() (3) (2) (2 3) (1) (1 3) (1 2) (1 2 3)) |