Thursday, May 27, 2010

ABCL 0.20.0 released, including first funded feature

On behalf of the developers of ABCL (Armed Bear Common Lisp) I'm glad to be able to announce the 0.20.0 release.

ABCL is a Common Lisp implementation implemented in Java and running on the JVM, featuring both an interpreter and a compiler. The compiler targets the JVM directly meaning that its output is runnable JVM bytecode. The fact that ABCL is written in Java allows for relatively easy embedding in larger applications. For integration with existing applications ABCL implements Java Specification Request (JSR) 223: Java scripting API.

This release is the first to include a funded feature: funds were provided to implement the CLOS METACLASS feature and tests. Next to that, this release contains a large number of fixes and improvements, such
as the ability to use JARs and URLs as pathnames and the a new ASDF version (ASDF2). You can find the full release notes at:

and the list of changes at:

Latest and older binary and source distributions can be downloaded from

Thursday, May 6, 2010

Running SLIME under cygwin with ABCL

If ABCL may be said to have an IDE, it has one in the combination of Emacs using the SLIME to connect to running Lisp instance(s). In the parlance of SLIME, Emacs is said to be the superior process with the running Lisp instance(s) known as the inferior Lisp process. With SLIME, Emacs provides symbol completion in a REPL with edit history, Lisp syntax highlighting, finding the source location for a given form, the ability to run multiple instances of the inferior Lisp (or even different versions of Lisps), the ability to interactively inspect Lisp values, a nice wrapper for controlling ASDF, and much more.

When confronted with a Microsoft Windows environment that I need to productively produce code in, the first thing I do is install the cygwin package to get to a minimal UNIX-like environment. Unlike many Windows enhancements, the installation of cygwin does not require Administrator privileges so it is possible even in a somewhat restricted corporate environment. cygwin provides a UNIX compatibility layer that has enabled the porting of many standard GNU utilities to run under Windows, including an X11 server.

One of the first packages that I install for use under cygwin is the Emacs X11 package, which provides The One True editor with a lot of tools that make simple programmatic tasks easy, and the construction of complicated system possible. Historically there have been other efforts to bring Emacs to Windows such as NTEmacs, but now that GNU Emacs 23.1 runs fine in an X11 server with cygwin, I think the ease by which cygwin installs and updates outweighs putative advantages of Windows-specific Emacs ports. In truth, over time, GNU Emacs has absorbed most of the useful features pioneered by other, more native, versions.

People have reported that they have been able to get SLIME working with Emacs under Windows, but I never had much success, maybe because cygwin imposes a UNIX-like pathname structure that are naturally quite different from Windows pathnames. Not only is the '\' <--> '/' convention switch, Windows drive letters (like 'C:') are mapped to mounts unto the UNIX-like root filesystem, so 'C:\' becomes '/cygdrive/c'. Since ABCL under Windows runs on the JVM it expects to be dealing with Windows pathnames, it never worked for me. Until today. Or rather, yesterday. So, without further ado about pathnames, here's …

HOWTO install SLIME under Windows for ABCL

0. Install cygwin, selecting the 'emacs-x11' and 'cvs' packages in the interactive chooser.

1. Make a directory called 'c:\work' to contain ABCL and SLIME. You can of course use whatever directory you wish here, but the adjust the rest of these instructions to whatever you choose. Under cygwin, this directory will appear as '/cygdrive/c/work'.

2. Install ABCL under 'c:\work\abcl', so that 'c:\work\abcl\abcl.bat' invokes ABCL.

3. Use CVS to retrieve a copy of SLIME HEAD later than 2010-05-05. SLIME doesn't do releases which put me off for a bit at first, so even though there is a slime-2.0 floating around somewhere, it's ancient by this time, and a release process probably won't be repeated by the SLIME community in the foreseeable future.

From the bash prompt you installed in step 0, from the /cygdrive/c/work directory issue the following command:
cmd$ cvs -d checkout slime
This will checkout a copy of SLIME including documentation. Alternatively one may download a CVS snapshot but then it will be harder to update SLIME later if you wish.

4. Use Emacs to edit '~/.emacs' to contain the following code
;;; .emacs for SLIME working with cygwin emacs

(add-to-list 'load-path "/cygdrive/c/work/slime")
(setq slime-lisp-implementations
'((abcl ("/cygdrive/c/work/abcl/abcl.bat"))))
(require 'slime)
(slime-setup '(slime-repl slime-asdf slime-fancy slime-banner))

(defun slime-to-lisp-translation (filename)
"\n" "" (shell-command-to-string
(format "cygpath.exe --windows %s" filename))))

(defun lisp-to-slime-translation (filename)
"\n" "" (shell-command-to-string
(format "cygpath.exe --unix %s filename"))))

(setq slime-to-lisp-filename-function #'slime-to-lisp-translation)
(setq lisp-to-slime-filename-function #'lisp-to-slime-translation)
This code sets up SLIME to be autoloaded by Emacs, using the 'cygpath.exe' to translate pathnames between the cygwin UNIX conventions (which Emacs expects), and the native conventions (which ABCL running on the JVM expects).

5. Upon evaluating the elisp code which you just used to configure SLIME (which can be affected by restarting Emacs), SLIME can be invoked via "M-x slime". ABCL will be invoked as a separate process, it will compile the elisp server known as swank that communicates between Emacs and the inferior Lisp process, it will load that code to initiate a connection, you'll see some "flying letters" coalesce into a REPL with a message in the mini-buffer welcoming you to SLIME

Happy hacking!