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;;; Haunt --- Static site generator for GNU Guile
;;; Copyright © 2015 David Thompson <davet@gnu.org>
;;;
;;; This file is part of Haunt.
;;;
;;; Haunt 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.
;;;
;;; Haunt 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 Haunt. If not, see <http://www.gnu.org/licenses/>.
;;; Commentary:
;;
;; Miscellaneous utility procedures.
;;
;;; Code:
(define-module (haunt utils)
#:use-module (ice-9 ftw)
#:use-module (ice-9 match)
#:use-module (srfi srfi-1)
#:use-module (srfi srfi-26)
#:export (flatten
flat-map
string-split-at))
(define* (flatten lst #:optional depth)
"Return a list that recursively concatenates the sub-lists of LST,
up to DEPTH levels deep. When DEPTH is #f, the entire tree is
flattened."
(if (and (number? depth) (zero? depth))
lst
(fold-right (match-lambda*
(((sub-list ...) memo)
(append (flatten sub-list (and depth (1- depth)))
memo))
((elem memo)
(cons elem memo)))
'()
lst)))
(define (flat-map proc . lsts)
(flatten (apply map proc lsts) 1))
(define (string-split-at str char-pred)
(let ((i (string-index str char-pred)))
(if i
(list (string-take str i)
(string-drop str (1+ i)))
(list str))))
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