Category Archives: haskell

Themes on Streams, Part II

Posted on May 20, 2011 by

In a previous post I claimed that comonad structures on R -> a are in one-to-one correspondence with monoid structures on R. In this post and the next I’ll justify that claim. Characterizing comonads on R -> a Suppose we … Continue reading →

Posted in haskell, math | Tagged , , , , | 2 Comments

Tic-tac-toe maps with diagrams

Posted on May 18, 2011 by

Inspired by Randall Munroe, here are some handy guides to optimal tic-tac-toe play, created with the diagrams EDSL. Click the images to open (zoomable) PDF versions. I hacked this up in just a few hours. How did I do it? … Continue reading →

Posted in haskell, projects | Tagged , , , , | 12 Comments

Announcing diagrams preview release

Posted on May 17, 2011 by

I am extremely pleased to announce a "developer preview" release of the diagrams framework for declarative drawing. This is a well-thought-out, well-documented, working release with all core functionality in place, but with many planned features still missing (for example, support … Continue reading →

Posted in haskell, projects | Tagged , , , , , | 7 Comments

trapd

Posted on May 11, 2011 by
Posted in haskell, humor | Tagged , , , , | 4 Comments

Themes on Streams

Posted on May 9, 2011 by

> {-# LANGUAGE DeriveFunctor, FlexibleInstances #-} Recall that a stream is a countably infinite sequence of values: > data Stream a = a :> Stream a > deriving (Functor, Show) > > sHead (a :> _) = a > sTail … Continue reading →

Posted in haskell, math | Tagged , , , , , | 3 Comments

Monoids for Maybe

Posted on April 18, 2011 by

The other day I had two lists of monoidal values that I wanted to combine in a certain way, and I realized it was an instance of this more general pattern: > {-# LANGUAGE GeneralizedNewtypeDeriving #-} > import Data.Monoid > … Continue reading →

Posted in haskell | Tagged , , , | 8 Comments

Call for contributions: second edition of the Typeclassopedia

Posted on April 3, 2011 by

The Typeclassopedia, by all accounts, has turned out to be a popular and useful resource for Haskell programmers. I’ve been thinking for a while about putting out a revised and expanded second edition, and it’s finally time. Planned changes include: … Continue reading →

Posted in haskell, writing | Tagged , , , , | 17 Comments

Binders Unbound

Posted on March 28, 2011 by

Stephanie Weirich, Tim Sheard and I recently submitted a paper to ICFP entitled Binders Unbound. (You can read a draft here.) It’s about our kick-ass, I mean, expressive and flexible library, unbound (note: GHC 7 required), for generically dealing with … Continue reading →

Posted in grad school, haskell, projects, writing | Tagged , , , , , | 7 Comments

Enumerating linear inhabitants

Posted on February 24, 2011 by

This is post number four in an ongoing series (#1, #2, #3) exploring the combinatorics of linear lambda calculus. In this literate Haskell post, I exhibit some code for enumerating all possible linear inhabitants of a given type, making use … Continue reading →

Posted in haskell | 1 Comment

Math.OEIS needs a new maintainer

Posted on December 4, 2010 by

Summary: the OEIS has switched servers and the oeis package needs updating to match, so I’m looking for someone to take over development. All the rest is padding in the form of entertaining stories. Recently, Michael Snoyman’s wonderful packdeps tool … Continue reading →

Posted in haskell, math, projects | Tagged , , , , | 4 Comments