Thursday 3 January 2013

Functional Programming Whinging

Tim Bray thinks Uncle Bob Martin's post on Functional Programming Basics is the cat's pyjamas.

Meh. "Basics" is the key word in that title - the article is pretty light and fluffy.  Fine if you don't know squat about FP, but it's also accompanied by a whole lot of starry-eyed razzle-dazzle which isn't really justified by the content (and note that I'm not saying it's wrong, just not substantiated).

To be fair, TB does have a few gripes.  Here's a few more:

  • The example used to show how FP wonderfully avoids variables and side-effects is that hoary old one of computing squares of integers.  (I mean really hoary - this was the first program I ever wrote, in WATFIV.  And I at least had cool line printer output!)  How about using something that's a bit more representative of an actual computational problem?  Like say, red-black trees - with deletion!  
  • As TB points out, the people who really need to make algorithms run fast across 64 cores are a small percentage of current coders.  For everyone else, scale-out is a more mundane but pressing problem.  And it's not clear to me whether FP will make that easier.
  • As someone who spends his leisure hours trying to make spatial algorithms more performant, I'm suspicious of anything that promises to automagically make code go faster across multiple cores.  In spatial most interesting problems are not "pleasantly parallel", and many of them are memory-bound as well as being compute-bound.  So advances in performance would seem depend on better algorithms, not a different choice of language.
Back in the day I was pretty keen on FP languages - but I realized after being exposed to Smalltalk and later Java, a lot of their appeal was due to their (necessary) provision of automatic memory management (which was painfully lacking in the "mainstream" languages such as FORTRAN, Pascal, C - oh, and even C++).

But I'm not trying to prove a negative here.  Certainly the FP features of no side-effects and lazy evaluation would seem to offer a lot of benefit for the right class of problems.  And FP or FP-ish languages are more mainstream than ever before.  So perhaps they really will become the mainstream language paradigm.  I just hope I don't have to be coding using layers of inconveniently situated parentheses.

Lead, the criminal element

I've heard before about the postulated link between atmospheric lead levels (courtesy of the leaded gasoline used through the middle decades of the 20th century) and crime levels.  This Mother Jones article America's Real Criminal Element: Lead is the best explanation I've seen so far (and has links to the original papers).  It really sounds like this hypothesis is fully confirmed - and the best thing about this story is that it has a happy ending.  (Unless you're trying to get elected as mayor - or Prime Minister - on a tough-on-crime platform).

There is a nice geospatial connection here.  As with many epidemiological issues, spatial locality is an important aspect of the analyses that lead (ahem) to the conclusion.  The article is chock-full of references to the spatial nature of the problem, such as:
We now have studies at the international level, the national level, the state level, the city level, and even the individual level
and my favourite:
a good rule of thumb for categorizing epidemics: If it spreads along lines of communication, he says, the cause is information. Think Bieber Fever. If it travels along major transportation routes, the cause is microbial. Think influenza. If it spreads out like a fan, the cause is an insect. Think malaria. But if it's everywhere, all at once—as both the rise of crime in the '60s and '70s and the fall of crime in the '90s seemed to be—the cause is a molecule.

Wednesday 2 January 2013

2012 Year in Review - Blog Roundup

A look back at 2012 from a software technology perspective by some of my favourite blogs:
  • Inspired By Actual Events - a wide-reaching roundup. I found the Java and friends links especially interesting, since the Java/JVM world is so big now it's hard to keep up with and distill the really significant events.
  • Interoperability Happens (Ted Nedward) - As usual, opinionated and insightful commentary on enterprise software technology from a hard-core developer perspective.
  • Tim Anderson - A strong focus on Microsoft, but also fairly even-handed assessment of the rest of the "A"-team (Apple, Android/Google, and Amazon).  (And a not-very-optimistic mention of the "B" team - BB/RIM). I always appreciate Tim Anderson's reading of the internal and external tea-leaves of MS technology.  It's always fascinating to see the elephant trying to jump, in a schadenfreudal sort of way.
  • Tim Bray - Not really a roundup, and not all that tech-focussed, but always a good read.