ezyang’s blog

the arc of software bends towards understanding

December, 2010

Gin and monotonic

Gin, because you’ll need it by the time you’re done reading this. Last time we looked the partial orders of values for data types. There are two extra things I would like to add: an illustration of how star-subscript-bottom expands and an illustration of list without using the star-subscript-bottom notation. Here is a triple of […]

  • December 8, 2010

Hussling Haskell types into Hasse diagrams

Values of Haskell types form a partial order. We can illustrate this partial order using what is called a Hasse diagram. These diagrams are quite good for forcing yourself to explicitly see the bottoms lurking in every type. Since my last post about denotational semantics failed to elicit much of a response at all, I […]

  • December 6, 2010

Talk Friday

I’ve had the pleasure of attending a number of really interesting talks over the past few months, so many that I couldn’t find time to write thorough articles for each of them as I did over the summer. So you’ll have to forgive me for putting two of them in compressed form here. There is […]

  • December 3, 2010

How I Learned to Stop Worrying and Love the ⊥

An extended analogy on the denotational and game semantics of ⊥ This is an attempt at improving on the Haskell Wikibooks article on Denotational Semantics by means of a Dr. Strangelove inspired analogy. The analogy. In order to prevent Brigadier General Jack D. Ripper from initiating a nuclear attack on Russia, the Pentagon decides that […]

  • December 1, 2010