Monthly Archives: November 2012

Teaching abstraction

I’m just beginning to prepare for the third incarnation of CIS 194, Introduction to Haskell in the spring. It’s occasioned some general thoughts on teaching abstraction which seemed worth writing down. Abstractions, of course, are everywhere in CS. By abstraction … Continue reading

Posted in teaching | Tagged , , , | 8 Comments

Combinatorial species definition

Continuing from my previous post, recall that the goal of species is to have a unified theory of containers with labeled1 locations. So, how do we actually specify such things (leaving aside for the moment the question of how we … Continue reading

Posted in math, species | Tagged , , , , | 5 Comments

foldr is made of monoids

> import Data.Monoid In his recent blog post What is foldr made of?, Tom Ellis made the clever observation that foldr is equivalent in power to the combination of map and compose, where > compose :: [a -> a] -> … Continue reading

Posted in haskell, math | Tagged , , , , | 15 Comments

Using multiple versions of GHC in parallel with GNU stow

Do any of the following apply to you? You sometimes hack on GHC. You sometimes want to try out an unreleased GHC version. You maintain a library and want to make sure it builds with several different versions of GHC. … Continue reading

Posted in haskell | Tagged , , , | 10 Comments