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 > <[email protected]> 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. > > > > > > > > _______________________________________________ > > Haskell-Cafe mailing list > > [email protected] > > http://www.haskell.org/mailman/listinfo/haskell-cafe > > > _______________________________________________ > Haskell-Cafe mailing list > [email protected] > http://www.haskell.org/mailman/listinfo/haskell-cafe _______________________________________________ Haskell-Cafe mailing list [email protected] http://www.haskell.org/mailman/listinfo/haskell-cafe
