#+TITLE: swankr: SWANK (and SLIME) for R
#+AUTHOR: Christophe Rhodes
#+EMAIL: csr21@cantab.net
* Introduction
  This is swankr, an implementation of the swank[fn:1] protocol for
  R[fn:2].  While the coverage of swank protocol functions is
  currently limited, enough is implemented for swankr to be useful: at
  the very minimum, it can be used to develop and extend itself.
** Relationship with ESS
   Emacs Speaks Statistics[fn:3] provides an interaction mode for R
   (among other statistical software packages), including an interface
   to R's toplevel, and keybindings to send input to R, to look up
   documentation, and so on.  Where it differs most noticeably from
   swankr is in the level of integration of various facilities with
   emacs: ESS uses the browser() debugger, whereas swankr provides its
   own debugger, sldb; swankr provides a custom REPL with hooks for
   common commands; and so on.  On the other hand, ESS is mature,
   feature-rich software, while swankr is only a little more advanced
   than a proof-of-concept.  For Lisp programmers, perhaps the most
   useful analogy is to say that swankr intends to be to ESS what
   SLIME is to ILISP.  At present, ESS mode remains active in R source
   buffers, providing font-locking functionality among other things.
* Installation
** Emacs configuration
*** Installing SLIME
    [[http://common-lisp.net/project/slime/][SLIME]] is required separately from swankr.  To install slime,
    perhaps the simplest is to pull the [[https://github.com/slime/slime][git sources]] into a
    user-specific site directory, and arrange for that to be on the
    emacs =load-path=; something like the following:
#+begin_src sh
mkdir -p ~/.emacs.d/site-lisp
cd ~/.emacs.d/site-lisp
git clone https://github.com/slime/slime.git
#+end_src

    Following that, I have in my =~/.emacs= (you will need to adjust
    paths to executables and source files):
#+begin_src emacs-lisp
;;; ~/.emacs.d/
(let ((default-directory (concat user-emacs-directory (convert-standard-filename "site-lisp/"))))
  (normal-top-level-add-subdirs-to-load-path))

;;; SLIME
(require 'slime)
(setq slime-net-coding-system 'utf-8-unix)
(slime-setup '(slime-asdf slime-repl slime-scratch slime-presentations slime-media))
(setq slime-lisp-implementations
      '((sbcl ("sbcl" "--dynamic-space-size" "2048" "--load" "/home/csr21/src/lisp/quicklisp/setup.lisp"))
        (git-sbcl ("sh" "/home/csr21/src/lisp/sbcl/run-sbcl.sh" "--dynamic-space-size" "2048"))
        (R ("R" "--no-save" "--max-vsize=4096M" "--interactive")
           :init (lambda (port-filename coding-system) 
                   (load "/home/csr21/src/R/swankr/swankr")
                   (format
                    "source('/home/csr21/src/R/swankr/swank.R', keep.source=TRUE, chdir=TRUE)\nstartSwank('%s')\n" port-filename)))))
(global-set-key (kbd "s-s") 'slime-selector)
#+end_src
*** Additional refinements
   In addition, for keybindings like =C-c C-c= to work properly, emacs
   needs to be told how to guess where a function definition begins.
   This can be achieved with /e.g./
#+BEGIN_SRC emacs-lisp
   (add-hook 'ess-mode-hook
     (lambda () 
       (setq defun-prompt-regexp "^\\(\\(\\sw\\|\\s_\\)+\\|\\s\"\\S\"+\\s\"\\)\\s-*\\(=\\|<-\\)\\s-*function\\s-*(.*)\\s-*")))
#+END_SRC
   Fontification of quoted function names is suboptimal by default in
   ESS; the following form in =~/.emacs= fixes that for ESS 5.11.
#+BEGIN_SRC emacs-lisp
   (eval-after-load "ess-common"
     (setq ess-R-mode-font-lock-keywords
           (append 
             (list '("\\(\\sw\\|\\s_\\)+\\s-*\\(=\\|<-\\)\\s-*function"
                     1 font-lock-function-name-face t)
                   '("\\s\"\\(\\S\"+\\)\\s\"\\s-*\\(=\\|<-\\)\\s-*function"
                     1 font-lock-function-name-face t))
             ess-R-mode-font-lock-keywords)))
#+END_SRC
*** Running
    After performing the installation steps above, =M-- M-x slime RET R
    RET= should start swank.  You will be prompted to accept a version
    mismatch -- simply accept -- then the SLIME REPL should start up,
    giving a prompt.  Enjoy!
* Development
  swankr's primary development repository is a git repository,
  accessible through
  <http://common-lisp.net/r/users/crhodes/swankr.git> and
  git://common-lisp.net/users/crhodes/swankr.git; a web view of the
  development history is [[http://common-lisp.net/gitweb?p=users/crhodes/swankr.git][available through gitweb]].  You can also view
  the current lists of [[file:BUGS.org]] and [[file:TODO.org]] items.
* Acknowledgments
  Thanks to my colleagues at [[http://www.gold.ac.uk/][Goldsmiths, University of London]], for
  suggesting that I investigate R for numerical and graphical
  investigations, and to my colleagues at [[http://www.teclo.net/][Teclo Networks AG]] for giving
  me motivation to get around to it.  Initial development was done at
  the [[http://ismir2010.ismir.net/][International Symposium on Music Information Retrieval]], which I
  attended (indirectly) thanks to the EPSRC-funded [[http://www.omras2.org/][OMRAS2]] research
  project and the [[http://www.londoninternational.ac.uk][University of London External System]]; Helmut Eller's
  partial implementation of swank for Ruby was an excellent blueprint
  to get development started.
* Footnotes
[fn:1] part of SLIME, the Superior Lisp Interaction Mode for Emacs:
<http://common-lisp.net/project/slime/>.

[fn:2] a free software environment for statistical computing and
graphics: <http://www.r-project.org/>.

[fn:3] also known as ESS, an emacs mode for interacting with a number
of statistical software packages, including R:
<http://ess.r-project.org/>.
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