Steven Pemberton, CWI, Amsterdam and W3C
Chair, W3C HTML and Forms Working Groups
This is a (nearly) Python-free zone
These slides are in XHTML, and intended for display with CSS projection mode.
ME
ME
= Maine
Looking at GA= Georgia, and FL= Florida, it appears that there is no real rule.
What I could work out is:
NE: Nevada or Nebraska?
NE: Nevada or Nebraska?
It's Nebraska, but NB would have been a better choice
NE: Nevada or Nebraska?
It's Nebraska, but NB would have been a better choice
MI: Mississippi, Missouri, Michigan, or Minnisota?
NE: Nevada or Nebraska?
It's Nebraska, but NB would have been a better choice
MI: Mississippi, Missouri, Michigan, or Minnisota?
It's Michigan, but MG would have been a better choice
NE: Nevada or Nebraska?
It's Nebraska, but NB would have been a better choice
MI: Mississippi, Missouri, Michigan, or Minnisota?
It's Michigan, but MG would have been a better choice
MS: Mississippi, Missouri, or Minnisota?
NE: Nevada or Nebraska?
It's Nebraska, but NB would have been a better choice
MI: Mississippi, Missouri, Michigan, or Minnisota?
It's Michigan, but MG would have been a better choice
MS: Mississippi, Missouri, or Minnisota?
It's Mississippi, but MP would have been a better choice.
But solving these problems with reading 2-letter codes would still not solve the problem of writing them.
Winter school was open in December
Water is warm
I couldn't believe it wasn't possible to do the 2-letter codes better.
So I wrote a program (in ABC as it happens; more on that later).
The best rule I came up with:
My point here is that the 2-letter codes were introduced because of automation.
But that is no excuse for ignoring the needs of people.
So last year was the 20th anniversary of the Mac. "The computer for the rest of us".
Well, the rest of them actually, because the type of person who turns up at a geek conference isn't likely to be your average computer user.
So let me tell you about people.
People have different psychological makeups.
This seems almost too obvious to be true, but it is surprising how many people don't properly understand it.
One theory, of Jung, uses 4 variables:
My favourite description of how people – particularly programmers – differ is in chapter 15 of Bruce "Tog" Tognazzini's book Tog on Interface.
When Sensories drive to work, they are aware of the birds, the trees, the hills turning green. They notice a cow lowing in the field. [...]
When Sensories drive to work, they are aware of the birds, the trees, the hills turning green. They notice a cow lowing in the field. [...]
Intuitives live in their own private universe, depending on an internal model of external events. [...]
When Sensories drive to work, they are aware of the birds, the trees, the hills turning green. They notice a cow lowing in the field. [...]
Intuitives live in their own private universe, depending on an internal model of external events. [...]
When Intuitives drive to work, they watch the tectonic plates, deep in the earth's crust, rubbing together...
When Sensories drive to work, they are aware of the birds, the trees, the hills turning green. They notice a cow lowing in the field. [...]
Intuitives live in their own private universe, depending on an internal model of external events. [...]
When Intuitives drive to work, they watch the tectonic plates, deep in the earth's crust, rubbing together. They run into the cow.
The fact is, people are strange, yes even you
For instance, writing text
The fact is, people are strange, yes even you
For instance, writing text
Playing chess: command interface, mouse interface, 'direct manipulation' interface with real pieces
Playing chess: command interface, mouse interface, 'direct manipulation' interface with real pieces
Hold your hand up
Count the number of triangles on the next screen
Drop your hand when you have counted
but count the red shapes
And this is why you need to design artefacts with people in mind, and do requirements and needs analysis, and you need to test on real people, and design incrementally.
Usability is about three things: doing it faster, doing it correctly, and enjoying it while you do it (for some value of 'it').
Usability is not necessarily about learnability: a harder to learn artefact may turn out to be more usable.
...now let me tell you something about computers.
To demonstrate Moore's Law
Take a piece of paper, divide it in two, and write this year's date in one half:
Now divide the other half in two vertically, and write the date 18 months ago in one half:
Now divide the remaining space in half, and write the date 18 months earlier (or in other words 3 years ago) in one half:
Repeat until your pen is thicker than the space you have to divide in two:
This demonstrates that the original Macintosh had comparatively tiny amounts of power, and that your current computer is more powerful than all other computers you have had put together
Badly...
Mostly for pixel pushing.
Most computers spend most of their active life idle.
Why aren't we using the extra power to make people's (our!) lives better?
For instance programming.
In the 70's, when programmers had to queue for 1 minute of time on a machine as powerful as a fraction of a Palm Pilot, programmers were free. Nowadays, hardware is free.
According to the DoD, 90% of the cost of software is debugging.
According to Fred Brookes, in his classic book The Mythical Man Month, the number of bugs increases quadratically according to code size: L1.5.
In other words, a program that is 10 times longer is 32 times harder to write.
Programming languages seem to always be designed for the machine. That may have been a wise decision in the 60's.
In the early 80's a group of us sat down to design a programming language (ABC) from the programmer's perspective.
Interesting team included: Dick Grune (CVS), Guido van Rossum (Python), Lambert Meertens
I looked for a photo of us all together, but did not find one.
However, I did find this one taken at a party...
Imagine, hypothetically, that programmers are humans...despite all evidence to the contrary:
Also pretend, just for a moment, that their chief method of communicating with a computer was with programming languages.
What should you do?
Treat it like a user interface design problem!
Order of magnitude easier to use: a program that would take you a week took you an afternoon.
Only 5 datatypes.
Mathematicians and cryptographers loved it.
Many at the time were shocked when we announced that it would never run on less than 128K!
Trick is: supply high-level primitives.
Guido van Rossum: Python
Dick Grune: CVS
Lambert Meertens: Programming as Mathematics (search for Bird-Meertens notation)
Others of us: Views, extensible markup language, structured vector graphics, stylesheets, a DOM, etc. (Ran on Atari ST)
An interesting part of Views was that it used declarative programming. For instance, the clock:
type clock = (h, m, s) displayed as circled(combined(hhand; mhand; shand; decor)) shand = line(slength) rotated (s × 60) mhand = line(mlength) rotated (m × 60) hhand = line(hlength) rotated (h × 30 + m ÷ 2) decor = ... slength = ... ... clock c c.s = system:seconds mod 60 c.m = (system:seconds div 60) mod 60 c.h = (system:seconds div 3600) mod 24
The nice part about declarative programming is that the computer takes care of all the boring fiddly detail (this is how spreadsheets work, and why they are so popular).
type histogram = list(number) displayed as row(box(?, width) * self) width = ...
box(h, w) is a function that returns a graphical box of
height h and width w.
box(?, w) returns a function of one parameter, where w has
been already filled in (i.e. currying)
f * list maps the (single parameter) function f onto the
list, returning a new list, so box(?, width) * self will return
a list of boxes all of the same width, and height depending on the original
values in the list.
row() sticks a bunch of graphical objects together
horizontally to create a single graphic.
Having written this browser, when the web came along we understood all about it.
I organised two workshops at the first web conference in 1994, one on electronic publishing, and one on 'client-side computation' (what we now call scripting). (Remember, this was before Javascript).
Shortly after I got involved with W3C
Later I started chairing two working groups at the W3C: HTML and XForms
As a result I have co-authored CSS, HTML4, XHTML, XML Events, XForms...
XForms is ostensibly a replacement for HTML Forms.
It has all the things you need for web forms, and it does much of the work on the client: validation, constraint checking, computations, ...
XMLDOMCSSJavascriptXHTMLXPathXForms
=Regular XHTML Browser
Time to build all of above: 3 programmers, 4 months
Total footprint (on IPAQ implementation): 400K (above Java VM)
But it also has a fully functional computational engine,
... and an output control...
In fact it is a declarative programming system...
This uses the same sort of techniques as in Views.
The styling language is SVG (using XBL).ö
This is a tremendous feat, written in some 150k-200k of Javascript
How long do you think it took to write?
Sidewinder maps is written in 25k of XForms
Uses SVG as style language
This would imply that it was some 15 to 20 times harder to write Google maps than Sidewinder maps.
The author of sidewinder maps says it took him about 10 days of part-time work
Which would mean that Google maps needed some 150 to 200 days of part-time work.
Usability is: doing it faster, doing it correctly, and enjoying it (for some value of 'it')
90% of the cost of programming is fixing the errors
The number of errors in a program is quadratic in the size of the program
Therefore we need to be investigating ways of reducing program size for the same functionality.
Computers are getting more powerful
People aren't.
We need to find ways of making computers take the load off our shoulders.
http://www.w3.org/2005/Talks/06-steven-goteborg