Monomorphic

In his first amendment to Human, All Too Human (1886), entitled Miscellaneous Maxims and Opinions, Friedrich Nietzsche states that

300. HOW FAR EVEN IN THE GOOD THE HALF MAY BE MORE THAN THE WHOLE. — In all things that are constructed to last and demand the service of many hands, much that is less good must be made the rule, although the organiser knows what is better and harder very well.He will calculate that there will never be a lack of persons  who can correspond to the rule, and he knows that the middling good is the rule. — The youth seldom sees this point, and as an innovator thinks how marvelously he is in the right and how strange is the blindness of others. (Helen Zimmern transl.)

Friedrich Nietzsche did not describe software making – I can only assume that he was describing authors and ideologists – but this seems to capture the difficulties of software development only too well. And it seems to give a recipe for how to overcome the communication difficulties (abandon exotic, over-refined solutions and focus on an easily understood middle ground, so that everybody can get together and comprehend the architecture). This was originally published in 1886.

With that, merry christmas!

In the chilly yet sunny winter afternoon, I took a walk past the imperial palace in the centre of Tokyo. I find sunny winter days refreshing.

The palace is interesting to behold. It is fronted by lots of that most precious of Tokyo commodities, open space. Supposedly, during the height of the land bubble, the land on which the palace is built was worth more than the state of California. This is in turn surrounded by some of Tokyo’s most prestigious office buildings in the Marunouchi and Hibiya districts. Tokyo station is just a few minutes away on foot.

The scene is one of juxtapositions. Open space meets tightly packed high rise buildings. Traditional Japanese architecture counters sleek office buildings. Yet this  never feels contradictory, because there is an underlying theme of restraint and control.

As you might expect from a royal residence, the public courtyard is immaculate. The grass is so well cut and even as to resemble a golf course. The trees on the lawn are of uniform height, lushness and distance from each other. The gravel is supremely even.

The office buildings are similarly controlled: shades of grey and brown, a certain minimalism and homogeneity in design that is easier found here than in Europe, the sense that unnecessary detail has been removed.

There is a sense of power in all this; a will and a shared set of ideas that have been realized to a high degree. The homogenous, flat skyscraper with a grid of windows is the triumph of human, platonic ideas over the organic and the irregular. The palace garden is man’s will taming the uncontrolled vegetation we find in nature. Yet such control is always a question of scale. We can cut and prune the trees, but we cannot control the color of their leaves or the exact angle of every branch. And we can cut and prune the buildings, but generally, we cannot control the shape of the overall skyline in detail. Something organic manifests itself in the multitude, even as some parts are controlled.

Power and rebellion, in constant struggle and symbiosis.

The Scala collections library (in version 2.7.7) has a MultiMap trait for mutable collections, but none for immutable ones. I hacked something up to use while waiting for an official version. I’m finding this to work well, but I don’t have much experience with collections design, so it’s likely to have some flaws. Also, this is a class and not a trait, so you can’t use it with any map you like. And from a concurrency perspective, maybe it’s sometimes better to use backing collections other than the HashSet and the HashMap.

 
import scala.collection.immutable._
 
/**
A multimap for immutable member sets (the Scala libraries 
only have one for mutable sets). 
*/
class MultiMap[A, B](val myMap: Map[A, Set[B]]) {
 
	def this() = this(new HashMap[A, Set[B]])
 
	def +(kv: Tuple2[A, B]): MultiMap[A, B] = {
	  val set = if (myMap.contains(kv._1)) {
		  myMap(kv._1) + kv._2
	  } else {
		  new HashSet() + kv._2	     	   
	  }
 
	  new MultiMap[A, B](myMap + ((kv._1, set)))
	}
 
	def -(kv: Tuple2[A, B]): MultiMap[A, B] = {
	  if (!myMap.contains(kv._1)) {
	    throw new Exception("No such key")
	  }
	  val set = myMap(kv._1) - kv._2
	  if (set.isEmpty) {
	    new MultiMap[A, B](myMap - kv._1)
	  } else {
		  new MultiMap[A, B](myMap + ((kv._1, set)))
	  }
	}
 
	def entryExists(kv: Tuple2[A, B]): Boolean = {
	  if (!myMap.contains(kv._1)) {
	    false
	  } else {
	    myMap(kv._1).contains(kv._2)
	  }
	}
 
    def keys = myMap.keys
 
     def values: Iterator[Set[B]] = myMap.values
 
    def getOrElse(key: A, elval: Collection[B]): Collection[B] = {      
      myMap.getOrElse(key, elval)
    }
 
    def apply(key: A) = myMap(key)
 
 
 
}

Usage:

 
   var theMultiMap = new MultiMap[String, Int]()
 
   theMultiMap += (("george", 1))
   theMultiMap += (("george", 3))
   theMultiMap += (("bob", 2))
   theMultiMap -= (("george", 1))

Here’s something I’ve wanted to see for some time, but probably don’t have time to work on myself.

It would be nice if there was a wikipedia-like web site for code and algorithms. Just the common ones to start with, but perhaps more specialised ones over time. Of course the algorithms should be available in lots of different languages. This would in fact be one of the main points, so that people could compare good style and see how things should be done for different languages. In addition, there should be an in-browser editor, just like on Wikipedia (but perhaps with syntax highlighting) so people can make changes easily.

Furthermore, there should be unit tests for every algorithm, and these should be user-editable in the same way as the main code. In an ideal world, the web site would automatically run the unit tests every time there’s a change to some algorithm and check in a new version of the code to a versioned repository. People could then trust with reasonable confidence that the code is valid and safe. However, if the system were to be as open as Wikipedia is, such a system wouldn’t work, since users could write unit tests with malicious code. So I suspect volunteers would have to download, inspect, and run the unit tests regularly, and perhaps there would be a meta-moderation system of some kind, allowing senior members to promote changes to the official repository. In the meantime, everybody should be allowed to see and edit changes on the wiki immediately, but they would be marked as “untested” or “unsafe”.

User interface would be very important since this kind of site needs to be fun and easy to use regularly.

Has this kind of project already been carried out by someone? I can find some things by googling. The Code Wiki appears to once have been a wikipedia of code, but it seems defunct, C# only, and now they’re selling a book with the contents of the site! Algorithm Wiki has many algorithms in different languages, but the user interface is awkward and littered with obstructive advertising, the code is hard to browse, and it doesn’t make for a usable quick reference. They seem to have gotten off to a good start though. Any others?

Edit: Rosetta Code seems to be the most mature and useful such site out there today.