Friday, August 22, 2014

iMaxima and Slime in EMACS

First of all, I am a Windows user. Lots of (probably) very helpful documentation for how to do this is not directly applicable to my setup, because I am not a Linux user. Bummer. That being said, it worked out in the end.

If you just want to hurry up and try Common Lisp in a REPL, then try Lispbox.

I recently set out to do two things:
  1. Get EMACS to run Slime (with any Common Lisp implementation)
  2. Get EMACS to run iMaxima
Slime

Watch Installing Common Lisp, Emacs, Slime & Quicklisp: It's a demo of installing EMACS with SBCL, Quicklisp, and Slime.
  • The primary hangup I was having until I saw this video is that I was trying to find a way to get EMACS to do something that I was supposed to do from within a running instance of a selected Common Lisp implementation. In other words, if you want to use CCL in EMACS using Slime, you should run CCL in a cmd window and use that REPL. Like many solutions, it's totally obvious when it is shown to you, which is why you may have trouble finding explicit statements about this.
  • If you want to see a few of the basic environment variable modifications in slow motion (as it were), see here.
To start slime, I launch EMACS and then type ALT-X slime ENTER.

iMaxima

Visit the main site for iMaxima to see what it's about. It also has a section for installation instructions. Most of what you need to know is on that website. Below are details from my own setup and additional research that helped me get the system up and running on my computer.

After you have EMACS setup and have decided your HOME folder (see here), run EMACS to let it create a ".emacs.d" folder. Then create or edit the file init.el (el means EMACS Lisp, I believe). Here is my entire init.el (largely excepting comments), which includes commands for a REPL with SBCL and iMaxima (separately):



Size of TeX output can be modified using (setq imaxima-fnt-size "xxxx"), where xxxx is one of small, normalsize, large, Large, LARGE, huge, or Huge. Also, by viewing the imaxima.el file, you can see a number of other options that are available to you.

To understand what's happening a bit better, it helps to know a few variables.
  1. Go to your scratch buffer in EMACS.
  2. Type inferior-lisp-program CTRL-j.
  3. You will get the output "sbcl" if you used my init.el file.
I suggest the scratch buffer because it is important in debugging when you don't have a working setup of anything else. The scratch buffer is available. It runs ELISP, EMACS' own Lisp dialect.

Here are a few other variables you might benefit from looking at:
  • load-path
  • exec-path
  • image-library-alist
I've bolded image-library-alist because it is really helpful to know what file you need to display png files. I snagged the files jpeg62.dll, libpng14-14.dll, and zlib1.dll from a couple of sources and placed them in "C:\Program Files (x86)\emacs-24.3\bin" which is where my "runemacs.exe" is. 
  • Notably, I got libpng14-14.dll and zlib1.dll from "C:\Program Files (x86)\Inkscape". (You really should try Inkscape, the free SVG editor, anyways.)
  • If your image-library-alist has other files in it, you either need to augment your image-library-alist (probably in your init.el file) or find one of the files already in image-library-alist and place it in the load path. You only need to do this for png files (as far as I know) in order to use imaxima.
A command you should try running (still in the scratch buffer) is

    (image-type-available-p 'png)

which will return T or NIL depending on whether the file type is available or not, respectively. If you get NIL, it means you don't have one of the files in image-library-alist in your load-path (or perhaps a dependee file is missing?).

Breqn

I had a lot of trouble with the display of the LaTeX even after I had a running imaxima session in EMACS. (Results of evaluations are usually displayed with LaTeX.) The problem stemmed from a missing package: breqn. I installed the mh package from within the MiKTeX Package Manger and it appeared to install fine, but my LaTeX was still not working properly within an imaxima session. The issue appears to have been related to dynamic loading of packages.

Here's what finally shook the problem loose: within TeXnicCenter I started a new project and included the line

    \usepackage{breqn}

along with the other \usepackage declarations that were part of that project. When I built the project I was prompted for the installation of the package and the installation appeared to go smoothly. Then I tried imaxima again and the LaTeX output worked.

To start an imaxima session, launch EMACS and then type ALT-x imaxima ENTER.

Piece of cake! :)

Additional Info (probably not necessary)

I'm still getting a warning message when I load imaxima, although it has yet to prove to be a problem. The warning is:
   (lambda (x) ...) quoted with ' rather than with #'

I also made another change, and I don't know if it was necessary or not (hopefully not), but while wrestling with something quite different I changed line 14 of maxima-build.lisp (that's "C:\Program Files (x86)\Maxima-5.31.2\share\maxima\5.31.2\src\maxima-build.lisp" on my system). I changed that line to:

(load "C:/Program Files (x86)/Maxima-5.31.2/share/maxima/5.31.2/share/lisp-utils/defsystem.lisp")

This is just an explicit file reference rather than a relative path. (In case you're wondering, I was trying, unsuccessfully, to compile maxima myself. Perhaps another time.)
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