Fast Haskell: Competing with C at parsing XML
In this post we’re going to look at parsing XML in Haskell, how it compares with an efficient C parser, and steps you can take in Haskell to build a fast library from the ground up. We’re going to get fairly detailed and get our hands dirty. A new kid on the block A few weeks ago Neil Mitchell posted a blog post about a new XML library that he’d written. The parser is written in C, and the API is
The constraint trick for instances
and thought, “Shenanigans! Why not just have this?” Me too! I only learned of this solution relatively recently, and I know experienced Haskellers who also only understood this recently or still don’t. Hence this quick write up. Here’s the thought process. We’re writing a trivial pretty printer and we’re using Writer. We write things like:
Lucid: templating DSL for HTML
I’m not big on custom templating languages, for reasons I’ll write about another time. I prefer EDSLs. I preferred the xhtml package back when that was what everybody used. It looked like this: header << thetitle << "Page title" thediv noHtml ! [theclass "logo"] << "…" thediv noHtml ! [identifier "login"] Pretty line-noisy to read, write and hard to edit in a reasonable manner. Later, blaze-html b
Dijkstra on Haskell and Java
In 2001, Edsger W. Dijkstra wrote a letter to the Budget Council of The University of Texas. A PDF is available here, I’ve typed it up so that everyone can read it. Sadly, the curriculum was changed to Java. Relatedly, the algorithmic language Scheme was replaced by Python in MIT’s The Structure and Interpretation of Computer Programs version 6.01. To the members of the Budget Council I write to y
Emacs support for debugging Haskell
One odd thing about the Haskell community is that we don’t use debuggers. We don’t even use stack traces. I think for several reasons: Haskell code goes wrong less often. Due to that, people are content with once in a while sticking in printf statements. Lazy evaluation is known to make debugging tricky. Haskell has no decent editor support for debugging. It’s at least my experience that when my H
The Fay Programming Language — A Haskell subset
IntroductionFay is a small programming language which has the following properties:A strict syntactic and semantic subset of HaskellStatically typedLazyPure by defaultCompiles to JavaScriptHas fundamental data types (Double, String, etc.) based upon what JS can supportHas a trivial foreign function interface to JavaScriptBecause Fay is intended to be small and simple, it relies on GHC, the Haskell
Ji, a little library for controlling a web browser from Haskell
Ji, a little library for controlling a web browser from Haskell As of recent I have only been creating a lot of new projects, not working one existing ones or finishing half done ones off.1So here’s yet another little project that is to test the concept of controlling the web browser’s DOM from Haskell as a means to write user applications.It doesn’t use websockets as websockets aren’t well suppor
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