Shape Typing
Just for entertainment, I recently tried to make type-safe Penrose tiles. It's a lot harder than I expected. The real
problem boils down to finding some way to do typesafe adjacency of two dimensional figures.
Say you have two values, both of which are two squares, one on top of the other. How can you infer at compile time that
placing the top two squares next to each other means that the bottom two squares are also next to each other?
Google's scholar search implies that shape databases and VHDL languages are
both interested in such ideas.
That makes perfect sense, type safety in VHDL layout would mean the compiler could check for layout bugs, for example,
to see if your layout sticks over the edges at compile time.
This reminds of someone on #haskell who said that if want adjacency in two dimensions, you should start in one
dimension.
So now I wonder, is adjaceny typing valuable in region allocation? I bet it is.
Dominic Fox is doing some nifty stuff with Polyominoes lately, but I can't tell if it has any relation to shape typing or not.
skew, aka Brandon Michael Moore, had an idea for a way to do type-safe shape operations with typeclasses, but as I was lacking sleep at the time, I could not understand it when he described it. He did make the point that arrow types work much like one dimensional shape types, and that did stick in my head.
April sunsets this far in the north are beautiful. It's 23:00, the dome of the sky is gray all the way down to a band of lighter blue and a stripe of red right at the horizon. This is the dress rehearsal for the midnight sun.
The snow is melting away, though big dirty piles still linger next to the roads and in the shaded areas. I've made it my personal project to try to force my way through the grungy bits left to follow the unicycle paths I rode before the snow covered them.
My legs are now strong enough to power my way through ankle deep snow and most of the mushy mud that is the result of the melting snow.
Swedes have bonfires on April 30. I forget exactly why, but I think it has something to do with the sun coming back.
The first year we were here I met two of our friends on the April 30th of that year, Marcus Löfgren and Rebecca Jonsson.
As much as I enjoy unicycling, it doesn't really do much for my arms. In hopes of escaping the stick figure problem, I've started doing 'shoulder-ups' where I do a handstand against a wall and lower myself down as much as I can without falling and then push back up to full arm extension. My shoulders feel larger already. Maybe that's just the strained muscles feeling... Recently on the #unicycling channel on freenode, I got some advice from Iain McCoy on the right way and the wrong way to do handstands and walking on hands.
