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-rw-r--r--kolam/utils.scm34
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+;;; kolam --- GraphQL implementation
+;;; Copyright © 2021 Arun Isaac <arunisaac@systemreboot.net>
+;;;
+;;; This file is part of kolam.
+;;;
+;;; kolam is free software; you can redistribute it and/or modify it
+;;; under the terms of the GNU Affero General Public License as
+;;; published by the Free Software Foundation; either version 3 of the
+;;; License, or (at your option) any later version.
+;;;
+;;; kolam 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
+;;; Affero General Public License for more details.
+;;;
+;;; You should have received a copy of the GNU Affero General Public
+;;; License along with kolam. If not, see
+;;; <http://www.gnu.org/licenses/>.
+
+(define-module (kolam utils)
+ #:use-module (ice-9 match)
+ #:export (pairify))
+
+(define (pairify lst)
+ "Return a list of pairs of successive elements of LST. For example,
+
+(pairify (list 1 2 3 4 5 6))
+=> ((1 . 2) (3 . 4) (5 . 6))"
+ (match lst
+ (() '())
+ ((first second tail ...)
+ (cons (cons first second)
+ (pairify tail)))))
+