On Thu, Jun 21, 2012 at 12:10 PM, Balazs Komuves
First, as the author of the executable-path library, it seems to me that the GHC docs are indeed correct saying that this is impossible to implement on some systems. My (conjectural) example for such systems are older BSD systems (FreeBSD before v6.0 iirc, NetBSD, OpenBSD). And these are even pretty standard Unix systems!
But not supported by GHC HQ: http://hackage.haskell.org/trac/ghc/wiki/Platforms This post suggests that we can implement it reliably on all major OS:es: http://stackoverflow.com/a/1024937/298847 The rest can return argv[0]. It's a big improvement over the current state of affairs (i.e. getProgName.)
Another serious issue is that the notion itself does not seems to be well-defined. For example think about symlinks (soft, hard?). Probably there exist other more strange Unix features I'm not aware of, which are complicating the matter further. Symlinks also exist on Windows by the way, though not advertised much.
getExecutablePath would return the actual executable (as found by the OS), bot symlinks. The OS has to resolve symlinks to run the executable, hence it knows where the executable is. -- Johan