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;;; kaakaa --- Tiny, security-focused AI agent in Guile
;;; Copyright © 2026 Arun Isaac <arunisaac@systemreboot.net>
;;;
;;; This file is part of kaakaa.
;;;
;;; kaakaa 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.
;;;
;;; kaakaa 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 kaakaa. If not, see <https://www.gnu.org/licenses/>.
(define-module (kaakaa lens)
#:use-module (srfi srfi-1)
#:use-module (srfi srfi-26)
#:use-module (srfi srfi-43)
#:use-module (lens)
#:export (vector-nth
in-json
push
prepend-over
alist-delete-over))
(define (vector-nth n)
"Like @code{nth}, but for vectors."
(lens (cut vector-ref <> n)
(lambda (vec proc)
(vector-append (vector-copy vec 0 n)
(vector (proc (vector-ref vec n)))
(vector-copy vec (1+ n))))))
(define in-json
(case-lambda
"Like @code{in}, but also allow integer components so that it is
possible to traverse JSON trees."
(() (id))
((key . tail)
(compose (apply in-json tail)
(if (string? key)
(key-ref key)
(vector-nth key))))))
(define (push lens x object)
"Cons @var{x} onto the part of @var{object} that @var{lens} focuses
on."
(over lens (cut cons x <>) object))
(define (prepend-over lens lst object)
"Prepend @var{lst} to the part of @var{object} that @var{lens} focuses
on."
(over lens (cut append lst <>) object))
(define (alist-delete-over lens key object)
"Delete @var{key} from the association list in @var{object} that
@var{lens} focuses on."
(over lens (cut alist-delete key <>) object))
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