[Haskell wikibook] Looking for opinions about "More on Lists" (and hello again!)
duplode_1 at yahoo.com.br
Wed Apr 4 03:46:09 CEST 2012
It has been nearly two years since I wrote a flurry of messages to this
list, while animatedly copy-editing and restructuring the early parts of
the Wikibook and, alongside Apfelmus, establishing grand plans for a
reorganization. Regrettably, the energy I had available to back such
efforts extinguished itself way too quickly...
Anyway, the book-writing bug has just bitten me again, and so over the
last few nights I worked towards making the early chapters less
confusing. Things are far from perfect, but I believe they are now
easier to follow, both for readers and for any contributors trying to
figure out what is missing. In particular, as far as I can tell the
creeping problems with chapters having prerequisites found later in the
book have now been solved.
Beyond telling you of such developments, I also would like to ask for
your opinion on a specific chapter. Yesterday I reorganized "More About
Lists" in an attempt to
1. make it into a coherent story - one which starts with the "obvious"
recursive doubleList and ends with multiplyList n = map ((*) n);
2. give readers an informal, "en passant" primer on what higher-order
functions are, without getting down to technicalities; and
3. illustrating why map is so useful, of course.
The problem is that now I look at the finished text and worry that the
"Generalizing even further" section, which prepares the ground for the
introduction of map (and where most of the higher-order primer is), is
now too dense in information for a newbie. It would be perfectly
feasible to avoid most of the higher-order discussion by, immediately
after the first "real" paragraph, telling it bluntly that "Haskell
allows us to make our function more general by passing another function
as argument" and then going straight into the definition of map. (Such
an approach, by the way, would be much more in line with Apfelmus' plans
(documented in the list archives from around May 2010), which is a good
thing as his plans were coherent and had great potential.)
Summing it up, while I think there is some pedagogical value in my
current approach to "More About Lists", I have serious doubts on whether
it would work in practice. So I invite you to skim through it and share
your thoughts on those issues. Your help will be much appreciated.
More information about the Wikibook