[Haskell-cafe] real haskell difficulties (at least for me)

[Peter Verswyvelen]

What could be done is letting the community rate the quality of the modules
for each platform? Maybe with user comments? Like amazon.com (so we
hackazon.org ;-)  And using lambdas instead of stars for giving the rating
:)

On Tue, Jan 13, 2009 at 6:13 PM, Don Stewart <dons at galois.com> wrote:

>
> Well, the number one thing is to use Cabal and the cabal-install tool.
> That is the simplest way to avoid headaches.
>
> Regarding libraries in general, the platform project is underway, aiming
> to bless a set of stable, "batteries included" packages, saving
> duplicated work determining which, say, json library to use.
>
> -- Don
>
>
> jamiiecb:
> > I agree completely. There is not nearly enough documentation on
> > packaging in haskell and too many hackage packages are broken or do
> > not install. I know several people are working on improving this but
> > they seem do be doing so rather quietly. Could someone briefly outline
> > what improvements are planned and what stage the current work is at? I
> > remember seeing some demos at anglohaskell during the summer but
> > nothing since.
> >
> > Jamie
> >
> > On Tue, Jan 13, 2009 at 3:33 PM, Regis Saint-Paul
> > <regis.saint-paul at create-net.org> wrote:
> > > Hi,
> > >
> > > I've seen many times the monad topic coming around on the cafe and
> plentiful
> > > tutorials on monads have been published. However, as a complete Haskell
> > > newbie coming from OOP, I felt monads were not particularly difficult
> to
> > > grasp, and very exciting to work with.
> > >
> > > During my experiments with Haskell so far, the main problems I kept
> bumping
> > > into were not related to the language but to its libraries: their
> > > compilation and installation. Unfortunately, this topic has not
> received
> > > nearly as much attention. I was unable to find a comprehensive tutorial
> on
> > > how to deal with the variety of problems I get when trying to install
> > > Hackage packages. This turned out to be (and still is) THE main source
> of
> > > wasted time and headaches. And worse, unlike type problems, these are
> not
> > > interesting ones to solve.
> > >
> > > Thus, as a beginner, the package management is what is really getting
> in the
> > > way of switching to Haskell--not the language. Even books like Real
> World
> > > Haskell (otherwise excellent) ignore entirely the topic. Cabal and
> > > Cabal-install are clearly wonderful applications that make installing
> most
> > > packages very straightforward. Unfortunately, whenever this "standard"
> > > method for package installation fails (or when it is not available as
> with,
> > > e.g., gtk2hs), I find myself in complete disarray.
> > >
> > > Below are some of the questions and issues I faced regarding package
> > > management:
> > >
> > > - For a number of packages, cabal-install gets stuck and has to be
> killed. I
> > > assume this is due to some difficulties in solving the dependencies and
> it
> > > is fine, not all can be automated and cabal-install is not responsible
> for
> > > poor packages. But the question then becomes what to do from there? Is
> their
> > > some method to solve dependencies? How should we proceed to "debug" a
> > > package installation? How do gurus deal with that? (maybe some less
> known
> > > command line arguments? Or ways to figure out the problem and work out
> its
> > > solution (cabal-install is silent in such case)? In particular, how to
> know
> > > why did cabal get stuck in the first place?
> > >
> > > - Some packages on Hackage are reported as not building successfully
> with
> > > GHC6.10 (e.g., encoding) while others do not build with 6.8 (e.g.,
> salvia)
> > > and the later might depend on the former...What is one supposed to do
> in
> > > such case? For example, is it an appropriate way to proceed to compile
> a
> > > package with one version of GHC and then use the compiled package with
> > > another version of GHC? Is it safe? What could possibly go wrong? If it
> is
> > > the right way to go, how should we setup the two GHC versions? For
> instance,
> > > should we have a shared package configuration file and choose through
> the
> > > path which GHC is used or is there nicer way to set this up?
> > >
> > > - Taking for example the "encoding" package on Hackage. Last time I
> tried,
> > > the log was saying it fails to build on GHC 6.10, however, looking
> inside
> > > this Hackage log, I could see a successful compilation using "preferred
> > > versions". So it looks as if the thing can be compiled somehow. What
> should
> > > one do with this information? If cabal manages to compile it using this
> > > method on Hackage, then isn't cabal install just doing it on my disk?
> Is it
> > > possible through some command line? Is it possible manually (without
> > > cabal-install) and, if so, how? (I tried to copy-past the build
> instruction
> > > as it appeared on the log...that somehow compiled, but then, I failed
> to
> > > figure out how to install...)
> > >
> > > - I'm primarily a windows user and lots of my initial struggles
> probably
> > > came from that. After many difficulties, I figured out that installing
> MinGW
> > > and MSys was *THE* way to get a bit more of the things working. First,
> a lot
> > > of time would be saved by just saying clearly on the GHC download page
> that
> > > MinGW and MSys are mandatory installation (or even package that with
> GHC for
> > > the windows distribution if license allows, who cares the extra few
> Mb).
> > > Even if that is not technically exact, i.e., even if ghci and many
> trivial
> > > command line programs can work without, MSys and MinGW turn out to be
> quiet
> > > necessary whenever trying to install anything producing side effect.
> Making
> > > it plain that these two are necessary would real come has a great time
> > > savers for newbie like me on windows (personal opinion of course). Or,
> if
> > > another path exists to go without these two, I'd be very glad to learn.
> > > Besides, even these tools basic installation is not enough, you need
> > > automake and various things of the like. That makes me wonder if the
> most
> > > precious skill for programming with Haskell would not be a strong C/C++
> > > programming background.
> > >
> > > - In face of the difficulties with windows, I switched to Linux. While
> some
> > > things worked better, there were still lots of difficulties with
> package
> > > compilation. For instance, it is very difficult to figure out which
> Linux
> > > packages of a given distribution are needed for compiling this or that
> > > package. Again, gtk2hs is epitome here: which C development packages
> are
> > > needed to compile it is obscure at best (cairo, codeview, etc...). I
> ended
> > > up querying the Debian package management with any keyword found after
> > > running gtk2hs and randomly installing all the dev packages...And when
> > > gtk2hs finally compiled, it failed to install anyway. As of today, I've
> > > never been able to compile even the dumbest demo using gtk2hs whether
> on
> > > linux or on windows and whether using ghc 6.8.3 or 6.10.1. On windows,
> the
> > > automated setup install worked but did not allow me to compile with
> codeview
> > > and I still do not know how to add codeview to the install packages.
> Trust
> > > that I tried hard and read the docs thoroughly. Gtk2hs is just on of
> many
> > > examples; I had problems under Linux also with, e.g., Happs, yi,
> database
> > > things, etc. and figured out that the situation was roughly identical
> to
> > > windows with MSys and MinGW. So Linux appears not to be the right
> solution
> > > here. Maybe it's just that Linux users are more experienced with the
> GNU
> > > C/C++ libraries...but it won't help a windows user to switch to Linux
> since
> > > this knowledge can't be built out of thin air.
> > >
> > > - Would there be some binary version of cabal targeting various OSs? I
> > > believe the Haskell platform project is about that. But without waiting
> for
> > > a fair and objective selection of the packages (it seems to be the
> current
> > > status of the project), I'd be happy working with some authoritative
> bundle
> > > produced by a Haskell guru and would trust his subjective choices (who
> am I
> > > to question these choices anyway). Or even an image (e.g., virtual box
> or
> > > Xen) of a fully setup development environment since there are so many
> > > dependencies involved in, e.g., simply compiling GHC...
> > >
> > > Now, one might argue that these are not Haskell problems, that they are
> > > normal when dealing with non-mature packages. So let me explain why
> I've
> > > been trying hard to install these packages:
> > >
> > > As a beginner with no experience with emacs, I tried to find some
> IDE-like
> > > environment which would, at least, save me from manually reloading
> files in
> > > ghci or help me browse the source files. Following the Haskellwiki
> advice,
> > > that led to trying out Yi, Leksah, eclipsefp, or a Visual Studio
> extension.
> > > To this date, NOT ANY SINGLE ONE of these worked, be it on Linux or
> Windows.
> > > I had to resort to learning emacs which seems the only sensible choice
> > > available today.
> > >
> > > I am particularly unskilled, no question here. But, would a charitable
> soul
> > > take the pain of writing a comprehensive package management tutorial
> instead
> > > of a monad one, (s)he would have my deepest gratitude :)
> > >
> > > Apologies for the long mail.
> > >
> > > -Regis
> > >
> > > P.S. People on #haskell are wonderful. They helped me solve many
> issues.
> > > Unfortunately, solving specific instances of problem did not contribute
> much
> > > to a deeper understanding of the internal working. I find myself
> randomly
> > > trying things without knowing which would work or why; Hence this plea
> for a
> > > tutorial.
> > >
> > >
> > >
> > > _______________________________________________
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> > > Haskell-Cafe at haskell.org
> > > http://www.haskell.org/mailman/listinfo/haskell-cafe
> > >
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