[Haskell-cafe] Re: Tutorial uploaded
S Koray Can
skoraycan at aim.com
Thu Dec 22 02:06:29 EST 2005
Daniel Carrera wrote:
> As a newbie... I agree that a newbie should be able to write this fairly
> early on:
> main = do
> x <- getLine()
> putStrLn ("The answer is " ++ show(fib(read(x))))
I'd agree for some definition of 'early'. I'll elaborate:
This entire discussion is about 'breaking a cyclic graph of conceptual
dependencies'. Unfortunately, I don't think it can be done well in short
amount of time.
The above code snippet contains typeclasses (show, read, monadic IO,
lists), syntactic sugar (do, <-). When you say a 'newbie' should be able
to write that early on, I'd interpret that as 'a newbie should be able
to regurgitate this early on' because the next thing a newbie might want
to do is try to divide the result of fib by a float and wonder why he
can't do that, or try to debug his fib implementation by trying to
insert a putStrLn. There are numerous ways to frustration unless the
newbie is comfortable with typeclasses, monads, etc.
This happens all the time when somebody is learning a new language, but
it's most problematic for haskell because the breadth of knowledge (of
various concept of the language) a learner has to gather before he can
dive deep (formulation, compilation, execution, debugging) into an
actual (even trivial) program is larger than all popular languages out
In every language, the most powerful features make their ways into the
most basic elements (as they should so that the entire language
benefits, but then, lists are monads?!?!). Learners of C++ with a C
background are not as much troubled by "cout << yadda << endl;" even
though there is operator overloading, references and the streams class
hieararchy in that statement. You can close your eyes and pretend that
cout is just magic and re-visit that node when you are comfortable with
classes. I don't think we can break cycles easily like that in Haskell.
The mental load is very high, and with concerns about language features
vs complexity even in other languages (see
http://lambda-the-ultimate.org/node/view/1155) I think we are observing
a new phenomenon: languages worth learning from now on will be
increasingly difficult (heck, even Perl is difficult now), and we'll
have to do away with 'tutorials' mostly.
In fact what we have are not really tutorials (YAHT is a small book!
compare that with http://www.ocaml-tutorial.org/). I think it's a tall
order for a 'tutorial' to teach Haskell (which may be why we end up
reading 4-5 of them). In fact Hudak's Haskell book was the first
introductory language book I'd ever bought. That's why I think tutorials
can have be frustrating and it takes a well edited book and .
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