Category Archives: haskell

Binders Unbound

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

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Enumerating linear inhabitants

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

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Math.OEIS needs a new maintainer

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

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Typed type-level programming: status report

A few people have been bugging me (you know who you are ;-) about the current status of the project to allow automatic “lifting” of Haskell data constructors to the type level, to allow for typed type-level programming. I’ve written … Continue reading

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Species subtraction made simple

> {-# OPTIONS_GHC -fno-warn-missing-methods #-} > module Virtual where > > import Control.Applicative > import Test.QuickCheck Yesterday on #haskell, augur asked me to explain how subtraction works for combinatorial species. (For an introduction to species, see my paper from the … Continue reading

Posted in combinatorics, haskell | Tagged , , , , , , , | 14 Comments

Back from Baltimore

I’m finally back in Philly after attending ICFP, the Haskell Symposium, and the Haskell Implementors’ Workshop in Baltimore. I enjoyed meeting every person I met, so if I met you please feel free to instantiate the universal quantifier. Here’s a … Continue reading

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The Haskell Alphabet

Here’s a little something I’ve been working on in bits of spare time here and there for the past five months or so: The Haskell Alphabet I seem to recall it was inspired by a conversation in #haskell around the … Continue reading

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On a Problem of sigfpe

> {-# LANGUAGE TypeFamilies, EmptyDataDecls, TypeOperators, GADTs #-} At the end of his most recent blog post, Divided Differences and the Tomography of Types, Dan Piponi left his readers with a challenge: In preparation for the next installment, here’s a … Continue reading

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Typed type-level programming in Haskell, part IV: collapsing types and kinds

In Part III, we saw how the current state of the art in Haskell type-level programming leaves some things to be desired: it requires duplicating both data declarations and code, and even worse, it’s untyped. What to do? Currently, GHC’s … Continue reading

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Species and Functors and Types, Oh My!

My paper on combinatorial species and the species library (an improved version of my previous ICFP submission) has been accepted to the 2010 Haskell Symposium! I look forward to seeing people in Baltimore in September, and in the meantime the … Continue reading

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