Friday 9 March 2012

Battle of the SSLs - Round 2

In a comment to Battle of the Spatial Scripting Languages, Sean suggested that a slightly more in-depth test of language expressiveness might be this task, involving a sequence of CRS transformation and geometry cleaning.  Here's the JEQL equivalent:

ShapefileReader t file: "test_uk.shp";

trans = select * except GEOMETRY, 
               CRS.transform(GEOMETRY, "epsg:4326", "epsg:27700") geom from t;

clean = select * except geom, isValid ? 1 : 0 isValid, cleanGeom
    with { 
        isValid = Geom.isValid(geom);
        cleanGeom = isValid ? geom : geom; //Geom.buffer(geom, 0);
    } from trans;

ShapefileWriter clean file: "test_uk_valid.shp";

The code is spread out a bit for clarity.  It could have been done in single SELECT statement, apart from the isValid flag added for reporting purposes.  Note the use of the JEQL extension with clause, which improves code clarity, and also allows a more imperative style of coding which can sometimes be preferable.

Fiona gets points for being able to define any function directly in the language, but there's a price to be paid in code complexity.

Here's the result (seen in the new JEQL Workbench Geometry Viewer):

The TI-58/59 programmable calculators

Mobile computing is nothing new!  My first programmable device was a TI-58 calculator:

I spend many happy hours punching in the code for Lunar Lander (and less time actually playing it).  Wish I still had my coding sheets for the various apps I dreamed up.  (For some reason, the convention then was to write the key codes vertically, rather than horizontally.)

TI had their own app store, selling Solid State SoftwareTM on plug-in ROM modules.  Of course I got the Leisure one, which had a few lame games on it.  Then as now, though, I had a lot more fun coding up new apps than playing games...

The calculator cognoscenti will notice the image is actually the TI-59, with the built-in magnetic card reader for offline permanent storage.  Had one of those too, once I got tired of eternally punching in programs. The mag card reader was pretty finicky, but it sure was cool filling up that little vinyl case with all that software that never got used...

A couple of years later HP released the iPhone of the calculator era - the HP-41C, which had an alphanumeric display!  HP was just as opinionated as Apple, in their own way - if you wanted one of their gorgeous units, you had to grok RPN notation. Kinda reminds me of my current effort of learning git.  I never did get one of those units, because by that time it was a lot more rewarding to punch code into a real microcomputer....

Reminiscing about the PC Pre-Cambrian explosion

With the mobile meteorite looming ever larger over the landscape of Planet PC, it seems like a good time to recall some memories of the last major transition in the computer world. I call this the Pre-Cambrian explosion of Personal Computers.  It took place from the mid-70's to the early 80's, when dozens of entrepreneurial companies sprang up all hoping to hit the magic combination of hardware and software and sell a zillion units.

In a way, it was exactly the inverse of what is happening now. Back then, a myriad of bizarre life forms sprang up to fill the niche exposed by the advent of the microprocessor, only to be driven into extinction by the arrival of a behemoth with superior reproductive capability.

Whereas today, the new ecological zone was initially colonized by a single fierce predator, who may yet out-compete all other arrivals trying to crawl out onto the shore of the new territory.

On to a series of occasional posts on the Pre-Cambrian PC era...

Thursday 8 March 2012

Java's vision for the future

Just noticed this slideshow from QCon 2012 on the vision for Java's evolution over the next few versions.

Some highlights of JDK 8:
  • closures via lambda expressions
  • filter-map-reduce framework
  • modules
and further out:
  • JNI goes away!
  • support for big in-memory data (arrays) and data structure optimizations
A key driver of these enhancements is the transition to multi-core and the end of the free performance lunch.  This is a great graph that puts it in perspective - those flat lines are the lunch bill arriving.

QCon always has excellent presentations, so I'm sure there's some other thought-provoking slideware on that site as well.

Tuesday 6 March 2012

Battle of the Spatial Scripting Languages!

The gloves are down in this exchange on gis.stackexchange, over LOC counts for Fiona, JEQL, and GeoScript-JS.

Fiona takes one on the chin in the first round!  But Sean recovers quickly, and makes a hit by pointing out that Fiona allows defining new functions right in the scripting language.  This would be feasible in JEQL as well, by providing hooks to into JVM-based scripting languages.  And it's also very easy to develop extensions as simple Java functions or classes.

Now, this is really just a schoolyard scuffle over a very simple use case for spatial scripting.  What the fans really want to see is a face-off over a more complex task...