Quantum Computing and Lisp

Quantum Computing is a fascinating field, but currently a contentious one. The only examples we have of real-world, hardware quantum computers are the line of adiabatic quantum computers from D-Wave Systems—and many voices in the scientific community still protest its identification as such simply because it is not a full-fledged gate-model quantum computer complete with persistent quantum data storage and QRAM. However, by the strictest definition, any machine which exploits quantum mechanical phenomena for the purpose of computation is a quantum computer, and the D-Wave One and Two meet this definition.

For us in the Lisp community, Quantum Computing is even more important; one of the most surprising secrets of the D-Wave line of adiabatic quantum computers is that their low-level operating system is programmed in Common Lisp. Specifically, D-Wave uses SBCL. This choice is not accidental or arbitrary—Common Lisp is uniquely suited to the task of quantum computer programming.

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LET-OVER-LAMBDA fixed for SBCL 1.2.2

Thanks go out to Orivej Desh—he pointed out what I overlooked, and the LET-OVER-LAMBDA package now works with full functionality restored in SBCL 1.2.2. I have preserved the :safe-sbcl feature used for testing the version of SBCL, so that descending into comma-expr of sb-impl::comma is only enabled for SBCL 1.2.2+.

The updated code should be available in the August release of Quicklisp. If you have a fork or clone, please be certain to pull the latest changes from the master branch.

LET-OVER-LAMBDA broken in SBCL 1.2.2

As expected, the Quicklisp distribution of LET-OVER-LAMBDA is broken by the changes to the backquote reader macro in SBCL 1.2.2; although I expect this change breaks a good portion of Paul Graham’s macro code examples from On Lisp, as well.

A quick-fix suggested on Reddit is to use a “pseudo-flatten” for SBCL that also descends into sb-impl::comma-expr of sb-impl::comma. I will be testing this fix today, and hopefully pushing an updated version for the August release of Quicklisp.

Stay tuned.

UPDATE: modified LOL:FLATTEN to descend into comma-expr of sb-impl::comma objects, but no joy. I have currently disabled DEFMACRO! based code in LET-OVER-LAMBDA until I can find a better solution, and tested this against both v1.2.2 and v1.2.0-1 of SBCL (so if nothing else, it will at least build without errors).

If anyone knows of a better solution, feel free to leave a comment here or on the GitHub Issue thread.

Hacking Lisp in the Cloud, Pt. 3

Cloud9 -- New website and 3rd gen browser-based IDEToday Cloud9 announced the release of their new IDE to all customers. They also released their new website. The hiccups in the beta were all pretty minor, and were resolved quickly after reporting the bugs. Now, everyone can enjoy all the awesome new features.

The Cloud9 IDE supports more than 40 programming languages, Common Lisp included. As I mentioned in my previous post about the Beta, there are all sorts of new features that support a cleaner Lisp development cycle over the previous version—including auto-completion, file outline of top-level definition forms, custom runners, split-screen views, and more, all built on top of an Ubuntu workspace with sudo privileges. They’ve also streamlined the interface, collaboration tools, terminal, and over-all performance of the IDE.

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SLIME for Emacs Live

Emacs Live is a frakkin’ epic compilation of customizations and packages, streamlined for the ultimate hacking experience. As I mentioned in my last post, Adventures in Clojure, it’s under development by the same team as the Clojure bridge to SuperCollider, Overtone. The one downside? It was designed for hacking Clojure, so it doesn’t include SLIME and Common Lisp support out of the box, and of course, it completely replaces your ~/.emacs.d/ directory and ~/.emacs config file, so you lose your existing SLIME setup (and all your other customizations) when you install Emacs Live. Don’t panic, the Emacs Live installer is smart enough to move your existing ~/.emacs.d/ folder and ~/.emacs config file to a safe place.

Emacs Live does, however, offer a pretty neat interface for creating Live Packs, boxed collections of Emacs packages and customizations, that can all be loaded together as a single package via ~/.emacs-live.el, stored outside the managed ~/emacs.d/ directory so that they can be maintained across updates. This made it only slightly less trivial than normal to get SLIME set up and running in Emacs Live.

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Adventures in Clojure, with Overtone, Light Table, and Emacs Live

After last week’s Toronto Lisp User Group meeting, I decided to give Clojure a fair shake after all. Since Java has been my arch-nemesis since 1996, I’ve mostly avoided Clojure up to now solely because it is built on and plays so nicely with the JVM—but, I’ve been seeing more and more awesome projects in Clojure lately, to the point where I can no longer justify ignoring it.

In particular, the Clojure project that came up in the after-meeting chats that most grabbed my attention was Overtone. Overtone is, ostensibly, just a wrapper library to the SuperCollider audio engine. I’ve been playing with SuperCollider both natively and through the Common Lisp client, cl-collider, for a few months; but Overtone doesn’t feel like just a wrapper around SuperCollider. As the website describes it, Overtone combines “the powerful SuperCollider audio engine, with Clojure, a state of-the-art lisp, to create an intoxicating interactive sonic experience.” (emphasis my own). Based on what I’ve seen and achieved with it so far, I’m inclined to agree.

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Hacking Lisp in the Cloud, Part 2

This morning I got access to the new Cloud9 IDE beta—and I have to say… WOW. It’s slicker, it’s faster, it’s more stable, auto-complete recognizes Lisp definition forms from your open workspace files such as defun and defmacro, and most importantly, it only takes seconds to get your workspace set up with RLWRAP, SBCL and Quicklisp.

The new Cloud9 IDE is running on an Ubuntu backend workspace. Cloud9 has had terminal access to your project workspace for quite some time now, but I’ve found the terminal experience to be significantly smoother in the new beta. It stays connected now, no longer timing-out on you when switching tabs or stepping away from the computer for a minute. Users can also use sudo for root access, and as a result install any debian package from apt (amongst many other things, of course). Emacs 24 is already installed by default. I suspect that SSH tunneling to a remote SWANK server from the Cloud9 workspace is also now possible.

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