Daniel-Nikpayuk_SICP-Solutions/Chapter 2/2.2/exercise-2.32/exercise.lsp
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;; Copyright 2015 Daniel Nikpayuk
;;
;; This file is part of SICP Solutions.
;;
;; SICP Solutions is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License
;; as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.
;;
;; SICP Solutions is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty
;; of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
;;
;; You should have received a copy of the GNU General Public License along with SICP Solutions. If not, see
;; <http://www.gnu.org/licenses/>.
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(define (subsets s)
 (if (null? s)
  (list '())
  (let
   (
    (rest (subsets (cdr s)))
   )
   (append rest (map (lambda (e) (cons (car s) e)) rest))
  )
 )
)

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(define A (list 1 2 3))
(subsets A)
;(() (3) (2) (2 3) (1) (1 3) (1 2) (1 2 3))

