#+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.  For Lisp programmers, perhaps the most
   useful analogy is to say that swankr is to ESS what SLIME is to
   ILISP.  At present, however, ESS mode remains active in R source
   buffers, providing font-locking functionality among other things.
* Installation
** Running
   To begin using swankr:
   1. start R;
   2. load the swank.R file:
#+BEGIN_SRC R
      source("swank.R")
#+END_SRC
   3. at the R prompt, run
#+BEGIN_SRC R
      swank();
#+END_SRC
   4. within emacs, load and initialize slime;
   5. run slime-connect, accepting the default host and port, and
      acknowledging the protocol version mismatch.
   At this point, a R REPL should appear.
** Emacs customization
   At a minimum, slime needs to be set up to function.  I've
   used the following forms in my =~/.emacs=
#+BEGIN_SRC emacs-lisp
   (require 'slime)
   (slime-setup '(slime-repl slime-scratch))
#+END_SRCA
   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
* 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/crhodes/swankr/swankr.git; a web view of the
  development history is [[http://common-lisp.net/gitweb?p=users/crhodes/swankr.git][available through gitweb]].
* 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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