Covariance and contravariance

:: physics, maths, pointers

Physicists seem still to be taught about tensors as being, essentially, multidimensional arrays with special transformation rules which must be learned by rote. So I wrote a document which tries to present a more useful approach.

Road worn

:: music, photography

I play the guitar. Something that has been fashionable for some time is what are often called ‘road worn’ guitars. In other words new (but vintage-spec) guitars which have been aggressed in various ways to make them look old.

The cult of programming

:: computer, lisp

Programming is not meant to be easy and it’s important to make sure that it is as cryptic as possible otherwise people other than cult members might be able to understand it. Of course, you also need to make sure it’s pure, because otherwise cult members will laughingly throw you into a pit full of spikes and the rotting remains of other heretics.