;;; 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)))))