Library support and general haskell debugging
hi, i'm new to hat (and haskell), and i'm interested in using hat to get a trace of a simple (actually, not so simple to me) haskell program that uses the hscurses library (its included example application, ContactManager). i'm specifically trying to find out what hscurses IO calls are being made, and in what order. this in turn is because my numerous attempts to write applications based on this code (ie using hscurses.widgets) have runtime failures. however, i found to my surprise that hat doesn't actually support any libraries outside the ones. for something like hscurses, which provides bindings to the ncurses c library and is partly written in hsc, is there still a way to use it without subjecting myself to too much pain? aside: i understand that one can copy over pure haskell libraries and compile them using hmake, but is hat honestly useable in practice? also, the only other debuggers i've found are: hood (superceded by hat), debug.trace (which requires modification of your src), ghci's dynamic breakpoints (not yet done, and almost certainly too painful to try to get working/to work with), and buddha (which only seems to do static src transformations, so it doesn't look like it'll help me). is there no hope for me in haskell? thanks and happy new years, yang
"Yang"
however, i found to my surprise that hat doesn't actually support any libraries outside the ones.
We are all too painfully aware of this particular shortcoming of Hat. Just about everyone in Haskell now uses pre-packaged libraries, but Hat does not (easily) support them yet. Sorry, but the best advice I can give is to wait until the Hat developers fix this!
for something like hscurses, which provides bindings to the ncurses c library and is partly written in hsc, is there still a way to use it without subjecting myself to too much pain?
It is possible, but for a beginner in Haskell I expect the work involved to be too unpleasant. Here is a different suggestion that may help to solve your immediate problem. You only want to see the order of calls to I/O functions in the library. So you could manually create a wrapper for every function, that writes a message to a logfile before calling the original function. Then just call the wrappers instead of the originals. (It is easy to give the wrappers the same name as the original function, by using module qualification, so you can swap between logging and non-logging versions later on.) Example: module HsCurses where foo :: Foo -> Blargh -> IO Foo bar :: Bar -> Baz -> IO () module WrappedCurses where import qualified HsCurses foo a b = do appendFile "logfile" ("foo "++show a++show b) HsCurses.foo a b bar a b = do appendFile "logfile" ("bar "++show a++show b) HsCurses.bar a b module Main where --import HsCurses -- choose between original import WrappedCurses -- or logging version Regards, Malcolm
participants (2)
-
Malcolm Wallace -
Yang