I also had problems when I began reading RHW, early in my career as a Haskell beginner. The functional pearl on monadic parsers by Hutton and Meijer was a great help in understanding the thinking behind Parsec. While reading it, I had some difficulty understanding why certain functions should ever terminate, but once I got past that, it made chapter 10 of RWH much easier to understand. Also, the functional pearl on applicative functors by Conor McBride and a second author (can't recall his name) blew the door open on the subject, for me. On Sat, Oct 6, 2012 at 1:03 PM, Patrick Mylund Nielsen < haskell@patrickmylund.com> wrote:

I'm not totally sure if you're having problems with RWH, or think it's too easy, but here are my thoughts on both:

Both RWH and LYAH (http://learnyouahaskell.com/) are intended for beginners/people who just want to get started, and RWH tends to be regarded as the hardest to understand ("read LYAH then RWH.") (RWH is also specifically aimed at demonstrating how to solve practical problems, not "hard"/academical ones.) I too agree that LYAH is the easier one, and it is slightly more focused on the theory and concepts of Haskell, so I would definitely recommend checking that out. I found that the topics and chapters of the two books mix nicely--you don't get the feeling that you're just reading the same book twice.

For other Haskell-related writings, Simon Marlow is currently writing a book based on his Parallel and Concurrent Programming in Haskell tutorial (http://community.haskell.org/~simonmar/par-tutorial.pdf) for O'Reilly at the moment. In the meantime, I've found the Simons' papers to be interesting reading:

http://research.microsoft.com/en-us/people/simonpj/ http://research.microsoft.com/en-us/people/simonmar/

The level of the papers range from LYAH-style material to the more abstract/advanced a la Philip Wadler's Theorems For Free (http://ttic.uchicago.edu/~dreyer/course/papers/wadler.pdf) Most of Philip Wadler's papers are also very interesting: http://homepages.inf.ed.ac.uk/wadler/

So, you're probably at a level where you'll want to start looking for interesting academical papers on Haskell/FP and theory, then re-visit RWH once in a while. I found the papers on STM, Cloud Haskell, and Parallel Haskell, to be the most interesting, easy to understand, and practically useful.

On Sat, Oct 6, 2012 at 1:41 PM, Janek S. wrote:

...

I began learning Haskell 9 months ago. I still consider myself a beginner, but I'm progressing towards more advanced concepts. I read scientific papers (simpler ones) and books about Haskell and functional programming. Right now I'm reading Pearls of Functional Algorithm Design, Introduction to Functional Programming, Implementation of Functional Programming Languages and Real World Haskell. RWH is causing me a lot of trouble though. This leads me to frustration because book covers rather basic material. I just spent another 1,5 hour reading chapter 10 again and trying to understand how presented parsing functions work. Even if I am barely able to grasp what is going on I feel that I wouldn't know how to write such code by myself. Am I the only one having such problems with RWH?

Jan

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I found I had to keep switching between RWH and other books for these concepts to sink in. A really good resource that I don't see mentioned too often is the Haskell wikibook: http://en.wikibooks.org/wiki/Haskell I don't remember it covering parsec specifically but if you get grounded in all the concepts there, the RWH chapters on parsec will make more sense. It also helped me to take breaks from RWH and re-read chapters later. Also if you find yourself getting discouraged, I really like Brent Yorgey's article on the monad tutorial fallacy: http://byorgey.wordpress.com/2009/01/12/abstraction-intuition-and-the-monad-... It uses monads as an example but describes the process of learning difficult concepts. On Sat, Oct 6, 2012 at 12:54 PM, Janek S. wrote:

...

Also, the functional pearl on applicative functors by Conor McBride and a second author (can't recall his name) blew the door open on the subject, for me. Good to hear, it's in front of me on the desk and I'm planning to finish

Dnia sobota, 6 października 2012, Mark Thom napisał: that pearl tomorrow (BTW. Ross Paterson is the second author).

...

I'm not totally sure if you're having problems with RWH, or think it's too easy, but here are my thoughts on both: I consider RWH to be a bit too hard for me.

...

I too agree that LYAH is the easier one, and it is slightly more focused on the theory and concepts of Haskell, so I would definitely recommend checking that out. I already read LYAH.

...

For other Haskell-related writings, Simon Marlow is currently writing a book based on his Parallel and Concurrent Programming in Haskell tutorial (http://community.haskell.org/~simonmar/par-tutorial.pdf) for O'Reilly at the moment. In the meantime, I've found the Simons' papers to be interesting reading: Yes, I know about the upcomming book and I'm awaiting it. Right now I'm digging through REPA papers, but Marlow's tutorial is next on my list of things to read.

...

So, you're probably at a level where you'll want to start looking for interesting academical papers on Haskell/FP and theory, then re-visit RWH once in a while Well, I figured out that before I go into more academic stuff I should have more knowledge about the basics, which I thought would be covered by RWH. Hence my frustration from not understanding a book that's supposed to introduce people to Haskell.

I guess I'll start with reading some papers on parallelism and go back to RWH when I have more experience.

Jan

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