[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: Lisp Live buffer
From: |
tomas |
Subject: |
Re: Lisp Live buffer |
Date: |
Wed, 28 Dec 2022 10:25:24 +0100 |
On Wed, Dec 28, 2022 at 01:32:52AM +0100, Emanuel Berg wrote:
> Why doesn't this work?
>
> For sure, there is a mistake somewhere but it seems now matter how
> I change it I get the same result ...
>
> ;;; -*- lexical-binding: t -*-
> ;;
> ;; this file:
> ;; https://dataswamp.org/~incal/emacs-init/mvc/model.el
>
> (require 'cl-lib)
>
> (defun make-world (dim len &optional init)
> (or init (setq init "."))
> (if (zerop dim)
> init
> (make-list len (make-world (1- dim) len init)) ))
Heh. When you are making a higher-order world, you are
storing a ref to the same list in each of its slots.
So if you change something at a lower level *poof*
all are changed. Read the subsection "samenes and change"
in 3.1 of SICP [1] for a beautiful treatment (actually,
re-read SICP: a beautiful book)
Oh, I nearly forgot: if you want it to work, you'll
have to regenerate the lower-level worlds (or deep
copy them).
Cheers
[1]
https://mitp-content-server.mit.edu/books/content/sectbyfn/books_pres_0/6515/sicp.zip/full-text/book/book-Z-H-20.html
(Sorry: fragment links seem to be disfunctional)
--
t
signature.asc
Description: PGP signature
- Lisp Live buffer, Emanuel Berg, 2022/12/06
- Re: Lisp Live buffer, Jean Louis, 2022/12/06
- Re: Lisp Live buffer, Emanuel Berg, 2022/12/07
- Re: Lisp Live buffer, Jean Louis, 2022/12/23
- Re: Lisp Live buffer, Emanuel Berg, 2022/12/26
- Re: Lisp Live buffer, Emanuel Berg, 2022/12/26
- Re: Lisp Live buffer, Emanuel Berg, 2022/12/27
- Re: Lisp Live buffer,
tomas <=
- Re: Lisp Live buffer, Emanuel Berg, 2022/12/29
- Re: Lisp Live buffer, Emanuel Berg, 2022/12/29
- Re: Lisp Live buffer, Emanuel Berg, 2022/12/29
- Re: Lisp Live buffer, Emanuel Berg, 2022/12/29
Re: Lisp Live buffer, Madhu, 2022/12/08