Tag Archives: haskell

Idempotent Template Haskell

Yesterday I was looking for a way to have some Template Haskell code generate a definition for a certain identifier if and only if such a definition did not already exist. Essentially I want to be able to call the … Continue reading

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trapd

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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

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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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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

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Typed type-level programming in Haskell, part III: I can haz typs plz?

In Part II, I showed how type families can be used to do type-level programming in a functional style. For example, here is addition of natural numbers again: data Z data S n type family Plus m n :: * … Continue reading

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Improving GHC’s constraint solving

So I’ve been here at MSR Cambridge for almost two weeks now (!), working in the Programming Principles and Tools Group with Simon Peyton-Jones and Dimitrios Vytiniotis — and also collaborating with Stephanie Weirich and Steve Zdancewic, who are also … Continue reading

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Typeclassopedia in Japanese!

Satoshi Nakamura has published a Japanese translation of the Typeclassopedia. I don’t read any Japanese, but it sure looks cool, and I hope this will be a great resource for Japanese learners of Haskell. A big thank you to Satoshi … Continue reading

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