On Wed, Sep 29, 2004 at 08:29:47PM +0000, John Goerzen wrote:
So I am thinking about a ConfigParser for Haskell. The first thing that occured to me is that Haskell has no OO features, so I'm not sure what is the best way to handle the "class" and its various methods.
The next thing that occured to me is that, unlike OCaml and Python classes, Haskell has no mutable variables. A call like config.setOption("main", "initpath", "/usr") in Python -- which alters the state of the config object and returns nothing -- would be impossible in Haskell (unless perhaps the FiniteMaps are mutable somehow?)
I might define just two IO functions: parseConfig :: FilePath -> IO Config modifyConfig :: FilePath -> (Config -> Config) -> IO Config This way, you could do all the modification in pure functional code, which as Alastair said, would create a "new" Config rather than modifying the existing one. Of course, you could also define a writeConfig :: FilePath -> Config -> IO () but then a user of your class could accidentally overwrite a change, if you had two parts of the code which read the same config, each made separate changes, and then each wrote their separate changes. -- David Roundy http://www.abridgegame.org