Call for contributions: second edition of the Typeclassopedia

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:

• making suggested exercises stand out typographically and adding many more;
• updating information about various standard packages (mtl, transformers, etc.) to match the current state of affairs;
• switching away from Pointed as a stepping stone to Applicative in favor of a more semigroupoid-based approach;
• expanding the sections on comonads and arrows, which were a bit rushed in the first edition;
• many other small additions, clarifications, and corrections.

However, the first edition was immeasurably improved by suggestions and contributions from many readers, and I hope the same will be true for the second. So, what would you like to see in the second edition? Some prompts to help you think of ways to contribute:

• Is there a section you find confusing? Do you have a suggestion to improve its clarity?
• Do you have a suggestion for a good exercise?
• Do you know of an error, whether technical or typographical?
• Do you know of a good resource that could be added to the bibliography — an explanation, example, original/historical source, relevant humor, … ?
• Are you able and willing to contribute some text explaining some aspect of a more advanced type class (Category, Comonad, Arrow, …) in more depth, or more intuitively, than the existing text?

To contribute, you can send me email (byorgey at cis dot upenn dot edu). I’ll also be keeping this darcs repository up to date, so you’re welcome to send me darcs patches as well.

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 for his hard work; the Typeclassopedia is certainly not short!

Monad.Reader #13 is out!

Issue 13 of the Monad.Reader, which includes a revised version of the Typeclassopedia, is out. This version of the Typeclassopedia contains many updates and revisions. There are also three other great articles in this issue of the Monad.Reader, I hope you’ll check it out!

Typeclassopedia — a generic response

Thanks for all the fantastic feedback on the Typeclassopedia! Please keep it coming!

Such an outpouring of helpful comments and suggestions deserves a response, so I just wanted to write a quick note to say that I am reading every piece of feedback—whether here, on haskell-cafe, in #haskell, or on reddit—and fully intend to respond to each as appropriate. However, I probably won’t get around to it for a week or so, as at the moment I am focusing on digging myself out from all the other obligations that piled up while I was finishing the first draft. In the meantime, please keep sending me your suggestions!

However, there is one common suggestion I’ve received that I’d like to respond to now, which is that the Typeclassopedia should be put into wiki form. There are two main reasons I am submitting it for publication in the Monad.Reader, instead of creating it as a wiki in the first place:

1. There is something about the permanence and elegance of a finely typeset, well-edited publication that a collection of wiki pages cannot capture. This isn’t just an issue of presentation; it also affects the content: writing for the Monad.Reader means that my writing and presentation are better than if I had created pages on a wiki.
2. The Monad.Reader has a deadline; creating a wiki does not. Without a deadline, I probably never would have finished.

With that said, I think wikifying it after publication is a fantastic idea, and I hope that someone will take the initiative to do this. The Monad.Reader publishes all the source for each issue under a BSD license, so I don’t think this should be a problem.