Yang wrote:
hi all, i'm looking for advice on how to architect a simple widget library for vty/hscurses, but these beginner-level questions should apply to haskell applications in general. input/requests on any aspect of my design would be greatly appreciated - in return perhaps you'll get something you'd actually want to use!
i have studied in detail various haskell curses/vty apps, including yi, hmp3, riot, and hscurses.widgets/contactmanager. my immediate goal is to produce a set of composable widgets and a flexible framework that - as much as possible - reduces the amount of code a user has to write. my eventual goal is to make a functional gui library, along the lines of fruit/wxfruit/fg. to this end i've also read their literature, but i still do not understand enough about arrows/yampa/afrp.
Currently, the design of a functional UI library (be it graphical or for tty) is still an open research problem. Somehow, the arrow based approaches like Fruit etc. are not yet satisfying. A predecessor to this approach is FranTk. The early library Fudgets is in essence based on arrows but precedes their invention. The most recent development in this direction is Phooey. In the mean time, the medium level libraries wxHaskell and gtk2hs have gathered acceptance, mostly because they implement a full widget set while still being reasonably succinct. A predecessor is HToolkit drawing from ObjectIO. Despite being close to their imperative cousins, they already supersede them in expressiveness. They make an excellent base for further experiments, be it for arrows (wxFruit) or other recent approaches like PropLang. You have two options: * Search for the grail. Most likely, this doesn't involve much coding but much searching and has the risk of not finding it. But as the tty doesn't have many different widgets, you can concentrate on the high level ideas, i.e. how to get rid of IO and IORefs. Pumping your brain with ideas - as you already do - surely helps. * Implement an existing design. This way, you'll actually program something. I'd propose to implement something medium level along the lines of wxHaskell that can later be utilized in a high level approach. Maybe you can even create a cross platform interface, i.e. one that works for a tty and for graphical UIs at the same time. The author of HToolkit wrote a proposal on how to transparently enclose Windows, Mac and Gnome.
try to use it for a "real" application that has little to do with parsing or other purported strengths of the language.
Well, Haskell's "only" strength is that it gives you enough power to express your ideas, i.e. to compose great things from small ones. The strength of your ideas is your business :) In this sense, monadic parser combinators are not an inherent strength of the language, they happen to be powerful by themselves. Regards, apfelmus