PAX Documentation Browser

Tags: tech, lisp, Date: 2023-05-26

PAX got a Emacs-based documentation browser to make documentation generation a more interactive experience. The trouble with interactivity is, of course, that it's difficult to get the point across in documentation, so I made a short video that demonstrates the very basics. In a followup, I'll cover apropos.

There is Try

Tags: lisp, Date: 2022-10-16

Do or do not. There is now Try. I forgot to announce Try, my Common Lisp test framework, on this blog.

... read the rest of There is Try.

PAX v0.1

Tags: lisp, Date: 2022-02-16

PAX v0.1 is released. At this point, I consider it fairly complete. Here is the changelog for the last year or so.

New Features

... read the rest of PAX v0.1.

Journal, the Kitchen Sink

Tags: lisp, Date: 2020-09-04

Ever wished for machine-readable logs and TRACEs, maybe for writing tests or something more fancy? The Journal library takes a simple idea: user-defined execution traces and implements logging, tracing, a testing "framework" with mock support, and an Event Sourcing style database on top.

... read the rest of Journal, the Kitchen Sink.

Moving the Blog to PAX

Tags: lisp, Date: 2020-05-05

After more than five years of silence, I may be resurrecting my old blog. I already got as far as rewriting it using MGL-PAX, which is a curious choice because PAX is a documentation generator for Common Lisp. The blog "engine" is rather bare-bones but works admirably, especially considering that the implementation is only 72 lines of code, most of which deals with post categories and overview pages with shortened posts, something PAX hasn't seen the need for.

On the Design of Matrix Libraries

Tags: ai, lisp, Date: 2015-02-26

UPDATE: 2020-05-03 – Things have changed the during last 5 years. This is a non-issue in Tensorflow and possibly in other frameworks, as well.

I believe there is one design decision in MGL-MAT that has far reaching consequences: to make a single matrix object capable of storing multiple representations of the same data and let operations decide which representation to use based on what's the most convenient or efficient, without having to even know about all the possible representations.

... read the rest of On the Design of Matrix Libraries.

Bigger and Badder PAX World

Tags: lisp, Date: 2015-02-20

Bigger because documentation for named-readtables and micmac has been added. Badder because clicking on a name will produce a permalink such as this: *DOCUMENT-MARK-UP-SIGNATURES*. Clicking on locative types such as [variable] on the page that has just been linked to will take you to the file and line on github where *DOCUMENT-MARK-UP-SIGNATURES* is defined.

PAX World

Tags: lisp, Date: 2015-01-26

A promise of MGL-PAX has always been that it will be easy to generate documentation for different libraries without requiring extensive markup and relying on stable URLs. For example, without PAX, if a docstring in the MGL library referenced the matrix class MGL-MAT:MAT from the MGL-MAT library, it would need to include ugly HTML links in the markdown:

"Returns a [some-terrible-github-link-to-html][MAT] object."

... read the rest of PAX World.

Recurrent Nets

Tags: ai, lisp, Date: 2015-01-19

I've been cleaning up and documenting MGL for quite some time now, and while it's nowhere near done, a good portion of the code has been overhauled in the process. There are new additions such as the Adam optimizer and Recurrent Neural Nets. My efforts were mainly only the backprop stuff and I think the definition of feed-forward:

... read the rest of Recurrent Nets.

INCLUDE Locative for PAX

Tags: lisp, Date: 2014-12-06

I'm getting so used to the M-. plus documentation generation hack that's MGL-PAX, that I use it for all new code, which highlighted an issue of with code examples.

The problem is that, the ideally runnable, examples had to live in docstrings. Small code examples presented as verifiable Transcripts within docstrings were great, but developing anything beyond a couple of forms of code in docstrings or copy-pasting them from source files to docstrings is insanity or an OOAO violation, respectively.

... read the rest of INCLUDE Locative for PAX.


Tags: lisp, Date: 2014-10-20

I've just committed a major feature to MGL-PAX: the ability to include code examples in docstrings. Printed output and return values are marked up with ".." and "=>", respectively.

(values (princ :hello) (list 1 2))
=> (1 2)

... read the rest of Transcripts.

Higgs Boson Challenge Bits and Pieces

Tags: ai, lisp, Date: 2014-09-23

The Higgs Boson contest on Kaggle has ended. Sticking to my word at ELS 2014, I released some code that came about during these long four months.

... read the rest of Higgs Boson Challenge Bits and Pieces.

Higgs Boson Challenge Post-Mortem

Tags: ai, lisp, Date: 2014-09-23

Actually, I'll only link to the post-mortem I wrote in the forum. There is a also a model description included in the git repo. A stand-alone distribution with all library dependencies and an x86-64 linux precompiled binary is also available.

This has been the Kaggle competition that attracted the most contestants so it feels really good to come out on top although there was an element of luck involved due to the choice of evaluation metric and the amount of data available. The organizers did a great job explaining the physics, why there is no more data, motivating the choice of evaluation metric, and being prompt in communication in general.

... read the rest of Higgs Boson Challenge Post-Mortem.

Liblinear Support Added to cl-libsvm

Tags: ai, lisp, Date: 2013-04-09

In addition to the cl-libsvm asdf system, there is now another asdf system in the cl-libsvm library: cl-liblinear that, predictably enough, is a wrapper for liblinear. The API is similar to that of cl-libsvm.

Stackoverflow Post-Mortem

Tags: ai, lisp, Date: 2013-04-09

After almost two years without a single competition, last September I decided to enter the Stackoverflow contest on Kaggle. It was a straightforward text classification problem with extremely unbalanced classes.


Just as Bocsimackó did the last time around, his lazier sidekick (on the right) brought success. I would have loved to be lazy and still win, but the leaderboard was too close for comfort.

... read the rest of Stackoverflow Post-Mortem.


Tags: ai, lisp, Date: 2010-12-27

It hasn't even been a year yet since I first promised that alpha–beta snippet, and it is already added to Micmac in all its 35 line glory. The good thing about not rushing it out the door is that it saw a bit more use. For a tutorialish tic-tac-toe example see test/test-game-theory.lisp..

The logging code in the example produces output, which is suitable for cut and pasting into an org-mode buffer and exploring it by TABbing into subtrees to answer the perpetual 'What the hell was it thinking?!' question.

Nash Equilibrium Finder

Tags: ai, lisp, Date: 2010-12-26

While I seem to be unable to make my mind up on a good interface to alpha–beta with a few bells and whistles, I added a Nash equilibrium finder to Micmac, which is becoming less statistics oriented. This was one of the many things in Planet Wars that never really made it.

... read the rest of Nash Equilibrium Finder.

Planet Wars Post-Mortem

Tags: ai, lisp, Date: 2010-12-01

I can't believe I won.
I can't believe I won decisively at all.

The lead in the last month or so was an indicator of having good chances, but there was a huge shuffling of ranks in the last week and some last minute casualties.

... read the rest of Planet Wars Post-Mortem.

Important Update to the Planet Wars Starter Package

Tags: ai, lisp, Date: 2010-10-25

First, is it possible to get something as simple as RESOLVE-BATTLE wrong? Apparently, yes. That's what one gets for trying to port Python code that's pretty foreign in the sense of being far from the way I'd write it.

... read the rest of Important Update to the Planet Wars Starter Package.

Planet Wars Common Lisp Starter Package Actually Works

Tags: ai, lisp, Date: 2010-09-21

Released v0.6 (git, latest tarball). The way the server compiles lisp submissions was fixed, and this revealed a problem where MyBot.lisp redirected *STANDARD-OUTPUT* to *ERROR-OUTPUT* causing the server to think compilation failed.

Planet Wars Common Lisp Starter Package

Tags: ai, lisp, Date: 2010-09-19

The Google AI Challenge is back with a new game that's supposed to be much harder than Tron was this spring. The branching factor of the game tree is enormous, which only means that straight minimax is out of question this time around. Whether some cleverness can bring the game within reach of conventional algorithms remains to be seen.

... read the rest of Planet Wars Common Lisp Starter Package.


Tags: ai, lisp, Date: 2010-03-19

As promised, my UCT implementation is released, albeit somewhat belatedly. It's in Micmac v0.0.1, see test/test-uct.lisp for an example. Now I only owe you alpha–beta.

Google AI Challenge 2010 Results

Tags: ai, lisp, Date: 2010-03-01

For what has been a fun ride, the official results are now available. In the end, 11th out of 700 is not too bad and it's the highest ranking non-C++ entry by some margin.

... read the rest of Google AI Challenge 2010 Results.

Google AI Challenge 2010

Tags: ai, lisp, Date: 2010-02-11

Tron is a fun little game of boxing out the opponent and avoiding crashing into a wall first. The rules are simple, so the barrier to entry into this contest is low. Thanks to aeruiqe, who made the Common Lisp starter pack, it took as little as a few hours to get a very bare-bones algorithm going. It's doing surprisingly well: it is number 23 on the leaderboard at the moment with 43 wins, 2 losses and 9 draws.

Micmac Initial Release

Tags: ai, lisp, Date: 2010-02-06

From a failed experiment today, I salvaged Micmac, a statistical library wannabe, which for now only has Metropolis-Hastings MCMC and Metropolis Coupled MCMC implemented. The code doesn't weigh much, but I think it gets the API right. In other news MGL v0.0.6 was released.

Deep Boltzmann Machine on MNIST

Tags: ai, lisp, Date: 2010-01-18

Let me interrupt the flow of the MGL introduction series with a short report on what I learnt playing with Deep Boltzmann Machines. First, lots of thanks to Ruslan Salakhutdinov, then at University of Toronto now at MIT, for making the Matlab source code for the MNIST digit classification problem available.

... read the rest of Deep Boltzmann Machine on MNIST.

Introduction to MGL (part 3)

Tags: ai, lisp, Date: 2009-12-29

UPDATE: This post out of date with regards to current MGL. Please refer to the documentation instead.

In Introduction to MGL (part 2), we went through a trivial example of a backprop network. I said before that the main focus is on Boltzmann Machines so let's kill the suspense here and now by cutting straight to the heart of the matter.

... read the rest of Introduction to MGL (part 3).

Introduction to MGL (part 2)

Tags: ai, lisp, Date: 2009-12-17

UPDATE: This post out of date with regards to current MGL. Please refer to the documentation instead.

After Introduction to MGL (part 1), today we are going to walk through a small example and touch on the main concepts related to learning within this library.

... read the rest of Introduction to MGL (part 2).

Introduction to MGL (part 1)

Tags: ai, lisp, Date: 2009-12-02

This is going to be the start of an introduction series on the MGL Common Lisp machine learning library. MGL focuses mainly on Boltzmann Machines (BMs). In fact, the few seemingly unrelated things it currently offers (gradient descent, conjugate gradient, backprop) are directly needed to implement the learning and fine tuning methods for different kinds of BMs. But before venturing too far into specifics, here is a quick glimpse at the bigger picture and the motivations.

... read the rest of Introduction to MGL (part 1).

Object Initialization with Slot Dependencies

Tags: lisp, Date: 2009-07-04

Consider a class with a trivial initialization dependency between slots A and B:

(defclass super ()
 ((a :initarg :a :reader a)
  (b :initform 0 :initarg :b :reader b)))

(defmethod initialize-instance :after ((super super) &key &allow-other-keys)
 (setf (slot-value super 'a) (1+ (slot-value super 'b))))

(a (make-instance 'super)) => 1
(a (make-instance 'super :b 1)) => 2

... read the rest of Object Initialization with Slot Dependencies.

Global Compiler Policy

Tags: lisp, Date: 2009-06-30

A quick note to library implementors: the effects of DECLAIM are permitted to persist after the containing file is compiled, and it is unkind to mutate your user's settings. Personally, I find DECLAIM too blunt and prefer to add declarations within functions, even going as far as introducing LOCALLY subforms just to have a place on which to hang declarations. But if you are really set on using DECLAIM, please wrap it like this:

(eval-when (:compile-toplevel)
  (declaim (optimize speed)))

... read the rest of Global Compiler Policy.

Active Learning for cl-libsvm

Tags: ai, lisp, Date: 2009-06-22

Along the lines of active learning with python & libsvm, I added support for calculating distance of a point from the separating hyperplane to cl-libsvm. In binary classification, there is only one SVM involved and one hyperplane. However, with N-class problems, there is a binary SVM for each of the $N(N-1)/2$ pairs of classes, and there are as many separating hyperplanes, something the linked python code fails to take into account. As per the libsvm FAQ, the absolute value of the decision value (see PREDICT-VALUES, wrapper of svm_predict_values) divided by the norm of the normal vector of the separating hyperplane is the distance. PREDICT-VALUES and MODEL-W2S are sufficient to calculate it. Note that among the distributed binaries only the linux-x86 version has been recompiled with the necessary changes, but patched sources are also included for your recompiling pleasure.

Calling Convention Hacks

Tags: lisp, Date: 2009-04-19

SBCL's calling convention is rather peculiar. Frames are allocated and mostly set up by the caller. The new frame starts with a pointer to the old frame, then comes the return address, an empty slot and the stack arguments (the first three are passed in registers on x86).

... read the rest of Calling Convention Hacks.

X86oid Pseudo Atomic

Tags: lisp, Date: 2009-03-29

The relatively recent chit - chat about allocation and interrupts have had me looking at ways to speed up pseudo-atomic in SBCL.

 (defmacro pseudo-atomic (&rest forms)
  (with-unique-names (label)
    `(let ((,label (gen-label)))
       (inst or (make-ea :byte :disp (* 4 thread-pseudo-atomic-bits-slot))
             (fixnumize 1) :fs)
       (inst xor (make-ea :byte :disp (* 4 thread-pseudo-atomic-bits-slot))
             (fixnumize 1) :fs)
       (inst jmp :z ,label)
       ;; if PAI was set, interrupts were disabled at the same
       ;; time using the process signal mask.
       (inst break pending-interrupt-trap)
       (emit-label ,label))))

... read the rest of X86oid Pseudo Atomic.

Code Alignment on x86

Tags: lisp, Date: 2009-03-09

There has always been a lot of wiggling of SBCL boinkmarks results. It's easy to chalk this up to system load, but the same can be observed running the cl-bench benchmarks under more ideal circumstances. Part of the reason is the insufficient number of iterations of some tests: measurement accuracy is really bad when the run time is below 0.2s, and it is abysmal when there is other activity on the system, which is easy to tell even in retrospect by comparing the real and user time columns.

... read the rest of Code Alignment on x86.

Space Cadet

Tags: lisp, tech, Date: 2008-12-15

Emacs users often report problems caused by strain on the pinky finger, which is used to press the Control key. The standard answer to that is to map Caps Lock to Control. I believe that there is a better way:

Note the placement of modifiers: Control, Meta, Super, Hyper on both sides of Space in this order, with Control being the closest to it. Touch typers especially find having two of each key absolutely essential, and the symmetric placement appeals to me.

... read the rest of Space Cadet.