The best way to predict the future is to prevent it

Decades ago, image-editing software looked like MS Paint (or worse). Nowadays we have the ability to create fancy renderings in something like Blender and add all sorts of effects with Photoshop. Is that the sort of progress a "Moore's Law for Software" would be measuring?

One of the intrinsic problems with something like MLfS is that software "progress" is much harder to measure than transistor density. What if image editors make great progress but text editors are stagnant for a decade? What about search relevance improving steadily through the 1990s, then content farms cluttering results in the 2000s?

"There is no Moore's law for software."

That's because software comes from the realm of biology, not physics, improvements are path-dependent, historically determined and can quite easily get stuck at local maxima rather than finding globally optimum states.

Moore's Law has largely been sustained because we've just been been getting as much as we can out of one overarching idea (silicon and transistors), and incremental progress along that direction is inevitable when there's no stimulus to force exploration of a completely new direction altogether.

Like olefoo said, software is an entirely different game. In addition to the above point, the relative progress of software is also impeded by the fact that it has to cater to millions of different applications in the real world and perform under different constraints in each one. When it covers such a broad range of application, its hard to really see what the "best way" is,and there probably isn't one.

Final (and most important IMO) point - there's no way to simply characterize the progress of software into one number and see if it follows Moore's law. Given that the open source movement, social networking, sites based on user-generated content, and tons of other things have all been created in the last decade, we may not be doing that bad.

The pace of innovation in software is both staggering and obvious to anyone who takes a serious look at what you can do with a computer 10, 20, or 30 years in the past. We've done quite a bit with the advances Moore's law has given us, if you ask me. And software is hard and complicated because the problems it's tackling are hard and complicated. A basic UI, or a basic web page, is easier to make now than it's ever been. But the thing that keeps me comfortably in business is that no matter how much I produce, everybody still wants more stuff, faster and cheaper.

Knowing a bit about Alan Kay's work I have to say that some posts here are missing the point. In my view when he says that there isn't a Moore's Law for software he is asking why haven't we abstracted software development to the level where we can double our productivity every few years or months.

I think Alan Kay is best interpreted as saying "there has not been a Moore's law level of progress for software", not "there can be no Moore's Law for software".

I can think of two metrics by which software progress can be measured.

Measure 1: Consider a software to be a sequence of operations which generates some arbitrary particular string of bits. A measure of progress can be, for any random string of bits whose generation we view as useful, how far is the totality of code (libraries, OS portions, etc) from the true Kolmogorov Complexity? Then Moore's Law can be, is this difference between true and actual complexity decreasing exponentially? Put another way, is the level to which we can compress the code specification of software exponentially approaching it's limit? I don't think so. But I also don't think this measure is useful as its too abstract.

Measure 2: For any given piece of software from the past, is the total number of man years required to replicate it decreasing exponentially as a function of time? Again I don't think so, not uniformly. I think it's more polynomial.

Of course there is a theoretical manner by which Exponential progress can be made in software. But some people view it as a dangerous existential threat. Either way, achieving Moore's law for software is not something that should be stepped into blindly.

How come there isn’t a Moore’s Law for software?

There has been some progress on this front. Average programmer productivity has been roughly constant over the past several decades in terms of Source Lines of Code. (SLOC - Yes, it's a rotten metric, but it's good enough in huge aggregates.) SLOC per unit of functionality for mainstream languages stopped decreasing when we got to Smalltalk, and hasn't moved much since.

So to progress from here, we either have to:

    - reduce SLOC per unit of functionality
    - increase reuse of existing code
    - increase the rate at which programmers can write correct code

I'm not sure the 1st is a good idea. When languages get too terse, they get harder to understand, and maintenance and debugging are a big deal.

The 2nd has been happening more and more. The way communities share good code has indeed progressed and increased the power of the individual programmer in the past two decades.

The 3rd one is quite a complex issue. I suspect functional programming can play some kind of role here, but it will have to be packaged in a way which is palatable to the programming mainstream.

Much could be done by a programming language that can enable the application of functional programming in much the same spirit as John Carmack's post here:

http://www.altdevblogaday.com/2012/04/26/functional-programm...

Just as OO became mainstream through "impure" implementations, FP could become mainstream through an impure implementation enabling programmers to easily incorporate it into their existing projects.

How about an FP-Lint for popular programming languages that can flag non-FP code in regions that have been designated FP?

Actually there is a Moore's law equivalent for software: Yannis' law. http://people.cs.umass.edu/~yannis/law.html Discussion: http://news.ycombinator.com/item?id=4121404