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| | ;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2018 Clément Lassieur <clement@lassieur.org>
;;;
;;; This file is part of GNU Guix.
;;;
;;; GNU Guix 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.
;;;
;;; GNU Guix 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 GNU Guix. If not, see <http://www.gnu.org/licenses/>.
(define-module (gnu services utils)
#:use-module (srfi srfi-1)
#:export (push-tokens
with-tokens-to-list
flatten))
(define %tokens-stack (make-parameter #f))
(define (push-tokens . tokens)
"Push TOKENS to %TOKENS-STACK so that they will be returned by
WITH-TOKENS-TO-LIST."
(unless (%tokens-stack)
(error "not called within the dynamic extent of 'with-tokens-to-list'"))
(%tokens-stack (append (%tokens-stack) tokens)))
(define (with-tokens-to-list thunk)
"Call THUNK and return the tokens that were pushed to %TOKENS-STACK as a
list."
(parameterize ((%tokens-stack '()))
(thunk)
(%tokens-stack)))
(define (flatten . lst)
"Return a list that recursively concatenates all sub-lists of LST."
(define (flatten1 head out)
(if (list? head)
(fold-right flatten1 out head)
(cons head out)))
(fold-right flatten1 '() lst))
;;; Local Variables:
;;; eval: (put 'with-tokens-to-list 'scheme-indent-function 0)
;;; End:
|