#+TITLE:  Programming in Scheme for SICP
#+AUTHOR: Howard X. Abrams
#+DATE:   2022-03-01

A literate programming file configuring Emacs.

#+begin_src emacs-lisp :exports none
  ;;; ha-programming-scheme --- Configuration for Scheme. -*- lexical-binding: t; -*-
  ;;
  ;; © 2022-2023 Howard X. Abrams
  ;;   Licensed under a Creative Commons Attribution 4.0 International License.
  ;;   See http://creativecommons.org/licenses/by/4.0/
  ;;
  ;; Author: Howard X. Abrams <http://gitlab.com/howardabrams>
  ;; Maintainer: Howard X. Abrams
  ;; Created: March  1, 2022
  ;;
  ;; This file is not part of GNU Emacs.
  ;;
  ;; *NB:* Do not edit this file. Instead, edit the original literate file at:
  ;;            /Users/howard.abrams/other/hamacs/ha-programming-scheme.org
  ;;       And tangle the file to recreate this one.
  ;;
  ;;; Code:
  #+end_src
* Introduction
First, install MIT-Scheme, the Lisp dialect used throughout the SICP book:
=brew install mit-scheme= or =sudo apt install mit-scheme= .
#+begin_src sh
  brew install mit-scheme
#+end_src

Or better yet, let’s use Guile:
#+begin_src sh
  brew install guile
#+end_src
* Geiser (Scheme Interface)
The [[https://www.nongnu.org/geiser/][geiser project]] attempts to be the interface between Emacs and all the Schemes in the world. Since I can’t decide which to use, I’ll install/configure them all.
#+begin_src emacs-lisp
  (use-package geiser
    :init
    (setq geiser-mit-binary "/usr/local/bin/scheme"
          geiser-racket-binary "/usr/local/bin/racket"
          geiser-guile-binary "/usr/local/bin/guile"
          geiser-active-implementations '(guile mit)
          geiser-default-implementations '(guile))
    :config
    (use-package geiser-mit)
    (use-package geiser-guile)
    (use-package geiser-racket))
#+end_src
** Org Mode
:PROPERTIES:
:header-args:scheme:    :session *scheming* :results value replace
:END:
Do we need a Scheme work for Org Babel? According to [[https://orgmode.org/worg/org-contrib/babel/languages/ob-doc-scheme.html][this document]], we just need to make sure we add the =:session= variable to start the REPL.
#+begin_src emacs-lisp
  (use-package ob-scheme
    :straight (:type built-in)
    :config
    (add-to-list 'org-babel-load-languages '(scheme . t)))

#+end_src

Since the version of Scheme hasn't been updated with the deprecation, and subsequent removal of =org-babel-get-header=, we include it here:
#+begin_src emacs-lisp
  (defun org-babel-get-header (params key &optional others)
    (delq nil
          (mapcar
           (lambda (p) (when (funcall (if others #'not #'identity) (eq (car p) key)) p))
           params)))


#+end_src

Let’s test it out by defining a variable:
#+begin_src scheme
  (define a 42)
#+end_src

And simply using it:
#+begin_src scheme :var b=8
  (+ a b)
#+end_src

#+RESULTS:
: ;Value: 50

And what about Scheme-specific stuff needed for SICP?
#+begin_src scheme
  (inc 42)
#+end_src

** Install SICP
:PROPERTIES:
:header-args:scheme: :session sicp :results value replace
:END:
Let’s get the book available as an Info page:
#+begin_src emacs-lisp
(use-package sicp)
#+end_src

Still having difficulty getting the Scheme REPL to output the results back into this document. Let’s try Racket...

Normally, I would just [[info:SICP][read the book]], however, if we want to read the [[file:~/.emacs.d/straight/build/sicp/sicp.info][sicp.info]] file, we need this, at least, temporarily:
#+begin_src emacs-lisp
(add-to-list 'auto-mode-alist '("\\.info\\'" . Info-mode))
#+end_src
* Racket
Actually, let’s do this with [[https://racket-lang.org/][Racket]]:
#+begin_src sh
  brew install racket
#+end_src

While Racket, as a Scheme, should work with Geiser (below), let’s also get [[https://racket-mode.com/][racket-mode]] working:
#+begin_src emacs-lisp
  (use-package racket-mode
    :config (setq racket-program "/usr/local/bin/racket"))
#+end_src

Can we get Racket working with Org?
#+begin_src emacs-lisp
  (use-package ob-racket
    :straight (:host github :repo "DEADB17/ob-racket")
    :after org
    :config
    (add-to-list 'org-babel-load-languages '(racket . t)))
#+end_src
** Try It Out
:PROPERTIES:
:HEADER-ARGS:racket: :session racketeering :results value replace :lang racket
:END:
Working for values?
#+begin_src racket
  (* 6 7)
#+end_src

#+RESULTS:
: 42

Working for output?
#+begin_src racket :results output replace
  (define str-1 "hello")
  (define str-2 "world")
  (define all (string-join (list str-1 str-2) ", "))
  (display (string-titlecase all))
#+end_src

#+RESULTS:
: Hello, World

The interface is horrendously slow, as the =:session= doesn’t seem to work, and starting up a Racket REPL takes a long time.

** SICP and Racket
:PROPERTIES:
:header-args:racket: :session *rsicp* :results value replace :lang sicp
:END:
If using [[https://docs.racket-lang.org/sicp-manual/SICP_Language.html][Racket for SICP]], install the SICP language:
#+begin_src sh
  raco pkg install --auto --update-deps sicp
#+end_src

We now can give it a =#lang sicp= (or better yet, use the =:lang= header) to define certain SICP-specify features:

Let’s try this now:
#+begin_src racket
(inc 42)
#+end_src

#+RESULTS:
: 43

* Technical Artifacts                                :noexport:
Let's =provide= a name so we can =require= this file:

#+begin_src emacs-lisp :exports none
  (provide 'ha-programming-scheme)
  ;;; ha-programming-scheme.el ends here
  #+end_src

#+DESCRIPTION: A literate programming file configuring Emacs.

#+PROPERTY:    header-args:sh :tangle no
#+PROPERTY:    header-args:emacs-lisp  :tangle yes
#+PROPERTY:    header-args    :results none :eval no-export :comments no mkdirp yes

#+OPTIONS:     num:nil toc:nil todo:nil tasks:nil tags:nil date:nil
#+OPTIONS:     skip:nil author:nil email:nil creator:nil timestamp:nil
#+INFOJS_OPT:  view:nil toc:nil ltoc:t mouse:underline buttons:0 path:http://orgmode.org/org-info.js
