Optimal Layout

Inspired by xmonad on linux, I tried out Optimal Layout (version 1.1.2) for more efficient window management on Mac OS X. My work setup is a MacBook Pro with an external display and Spaces enabled. An important goal is to achieve keyboard only window control.

In Optimal Layout, tiling windows in an arrangement requires

1. explicitly selecting the windows in the Optimal Layout UI


2. selecting a layout from a list


3. selecting the target display

My most common use case is to arrange windows in the current space on the display with the focus, i.e. my current context. There are too many steps for this to feel efficient.

The available window layouts are predefined, including the window sizing. After arranging windows, sizing adjustments can be made using the sticky resizing feature, but this requires using the mouse. Furthermore, should you open one more window, you have to go through the whole process again.

I am disapointed with Optimal Layout and am trying out Divvy, which I will post about next.

Installing XMonad on Ubuntu 10.10 Maverick Meerkat

I installed Ubuntu 10.10 Maverick Meerkat (in Parallels on my Mac) to try out XMonad, the tiling window manager. XMonad is a candidate if I move off the Mac. I am slowly increasing my keyboard use and relying less on the mouse and XMonad is a further step in that direction.

I have never installed or used Xmonad before and after too much time stuffing around with the usual linux problems, these are the steps I followed to get a simple, initial installation working on a fresh install of Ubuntu.

1. Install Haskell, XMonad and dmenu.
   

   $ sudo apt-get install haskell-platform xmonad dwm-tools

   
   Originally, I installed Haskell and then tried to install XMonad via Cabal. Unfortunately the xmonad-contrib package failed to install due to dependency issues.


2. Set XMonad to be the window manager for Gnome.
   

   $ gconftool-2 -s /desktop/gnome/session/required_components/windowmanager xmonad --type string

   
   Found this at Xmonad/Using xmonad in Gnome. Don't log out or restart X now. If you do, you will find XMonad workspace 1 broken. It seems to consist of two Gnome panels tiled to fill the screen but hidden behind the desktop and any further windows you create are also hidden. The next step fixes this.


3. Create a simple Xmonad configuration file.
   

   $ mkdir ~/.xmonad
   $ touch ~/.xmonad/xmonad.hs

   
   Set the contents of xmonad.hs to
   

   import XMonad
   import XMonad.Hooks.ManageDocks
   
   main = xmonad $ defaultConfig {
           manageHook = manageDocks <+> manageHook defaultConfig,
           layoutHook = avoidStruts  $  layoutHook defaultConfig
           }

   
   Apply the configuration.
   

   $ xmonad --recompile

   
   This configuration was found at Xmonad/Config archive/John Goerzen's Configuration.
   


4. Logout and back in again. You should see a standard looking Ubuntu desktop with the menubar across the top and the normal panel along the bottom. See the tour to get started with the XMonad commands.

Defamation?

Yesterday I received a letter from lawyers representing a doctor named in my post Tony's letter to the Medical Board of Queensland. They claim the letter contains defamatory statements and demanded I remove the post.

At the time I posted this blog entry, Tony was missing and left a public message of possible self harm. People were looking for him, his family was worried and many people in the programming communities Tony frequented online feared for his safety. I published Tony's letter at that time for those people online that had seen and were discussing his message, but had no awareness of the real situation.

I do not wish to remove the blog post as it captures a small part of the prolonged trauma Tony endured in engaging with the medical system. I have no reason to doubt that all the practitioners Tony saw genuinely believed they were doing the right thing. This does not change the experience of the patient though. It can be a demoralising cycle of slowly progressing from generalists to specialists, booking appointments weeks/months into the future meanwhile enduring symptoms, bearing the financial burden, deciphering sometimes poor communication, having to evaluate practitioners and their advice and decide next steps in the face of enduring pain.

I am disappointed that one of the doctor's involved has resorted to this level of legal involvement against me. Instead of attempting to censor, he could have simply written a rebuttal. I defy anyone that claims the medical system (as a whole) handled Tony's case well. Therefore there is room for improvement that is better served by reflection and constructive criticism rather than a legal approach.

I am not a lawyer and have no experience with defamation law. I have removed the doctor's name from the blot post in an attempt to avoid legal confrontation.

Why are helmets mandatory for cycling?

The issue of mandatory helmet laws for cycling has been growing in public awareness. This is possibly due to recent court cases and research, the proported lack of take up of the Melbourne Bike Share and the brand new Brisbane CityCycle program.

Proponents of repealing mandatory helmet laws generally focus their discussion on practical issues. They cite the lack of compelling scientific research regarding helmet efficacy in preventing serious brain injury, the deteriorating overall physical health of society and improving sustainability through lower impact on the environment. My question is should they be required to do that?

Supposedly Australia is a free, civilised country. We value our individual freedom. This freedom includes daily choices concerning how our own actions affect our own good, balancing our own personal risk against convenience, benefit and enjoyment. We make these choices whenever we drive our cars, fly in an aeroplane, jump out of an aeroplane, take up smoking, drink varying volumes of alcohol and go swimming.

By definition mandatory helmet laws restrict individual freedom. The cyclist is unable to make the choice of balancing personal risk against convenience, benefit and enjoyment. It does not matter what type of bike is being ridden, the speeds, riding surface, distance travelled and presence or absence of vehicles.

So my question is why isn't the government required to justify the presence of mandatory helmet laws, since they are exercising power over individual freedom, against some people's will? Such a justification would necessarily be in terms of preventing harm to others, otherwise it impinges on the individual freedom we as a society also claim to value. If no such reasonable justification is available then repealing the laws is the sensible and rational course of action to take.

QOTD

I consider it extremely important–perhaps vital, even–to spend time engaging others intelligently who have diverging views from one’s own. I think that this is, on the whole, one of the most valuable uses of one’s time that exists. Whether it’s consulting a disagreeable book or a person, somehow at the intersection of intelligence and difference lies a “something” that is mind-expanding.

From Sealed Abstract - Why I stopped reading HN via @conal

Single exponential smoothing and foldl

Recently I looked at simple techniques for time series smoothing and forecasting. One such primitive method is the single exponentially weighted moving average (SEWMA), defined as



where the sequences are indexed from 1. denotes an observed value of the time series and a SEWMA value. In words, this recursive definition expresses that the next SEWMA value is a weighted average of the curent observed and SEWMA values.

If I pose the question "What is the predicted value for the next time series observation?" we just apply the formula.


A typical imperative implementation

sewma <- function (alp, y) {
  S <- y[1]
  for (t in 2:length(y)) { S <- alp * y[t] + (1-alp) * S }
  S
}

This is R code, but it should look familiar enough to anyone who has written Java, C#, etc.


Haskell implementation
In Haskell, a fold is a way of recursively iterating a data structure, accumulating a return value. The left fold has type

foldl :: (a -> b -> a) -> a -> [b] -> a
foldl f s y = ...

Denote one of the values from the conceptual sequence of accumulator values as . The function f maps from the current accumulator and list values to the next accumulator value



which is the form of the SEWMA equation above. The foldl1 function is a specialisation of foldl that uses the first value of the list as the initial accumulator value, yielding the implementation

sewma alp = foldl1 (\s y -> alp * y + (1-alp) * s)

Revisiting R
R has the Reduce function for performing folds.

sewma <- function (alp, ys) {
  Reduce(function (S, y) { S <- alp * y + (1-alp) * S }, ys[2:length(ys)], ys[1])
}

Summary
If accumulating a value over a data structure can be represented with a step function of the form



then a left fold captures the recursive implementation.

Haskell mode in MacVim

I set up Haskell mode (haskellmode-20100622.vba) in MacVim 7.3 (53). As a Vim newbie I found this page useful, even though it says pretty much the same thing as the Haskell mode project page.

I followed the instructions and created $HOME/.vimrc with these contents.

" use ghc functionality for haskell files
au Bufenter *.hs compiler ghc

" switch on syntax highlighting
set syntax on

" enable filetype detection, plus loading of filetype plugins
set filetype plugin on

" Configure browser for haskell_doc.vim
let g:haddock_browser = "open"
let g:haddock_browser_callformat = "%s %s"

Unfortunately when I edited a Haskell file none of the Haddock integration was working. I assume the haskell_doc.vim filetype plugin wasn't being loaded because the :DocSettings command failed with E492: Not an editor command.

After some hours I changed the line set filetype plugin on to :filetype plugin on and Haddock integration now works (don't know why). I am using the Haskell Platform which includes the documentation.

After reading A minimal Vim configuration I have switched from $HOME/.vimrc to $HOME/.gvimrc with these contents.

" line numbers
set number

" show the cursor line and column number
set ruler

" turn off blinking cursor in normal mode
set gcr=n:blinkon0

" hide the toolbar
set go-=T

" switch on syntax highlighting
set syntax

" highlight matches in a search (hls)
" show the current matching pattern as you search (is),
" ignore case (ic) unless you are searching for both upper and lowercase letters (scs)
set hls is ic scs

" use ghc functionality for haskell files
au Bufenter *.hs compiler ghc

" enable filetype detection, plus loading of filetype plugins
:filetype plugin indent on

" Configure browser for haskell_doc.vim
let g:haddock_browser = "open"
let g:haddock_browser_callformat = "%s %s"