Re: [Haskell-cafe] Typed Configuration Files
Neil Mitchell ndmitch...@gmail.com writes: The CmdArgs manual might help: http://community.haskell.org/~ndm/darcs/cmdargs/cmdargs.htm Yes, this is what I used :-) Presenting examples is great, but gives me the hubris to rip off the example that seems to fit most closely, and modify it. This makes for a quick start, but also for the odd misunderstanding. I'd describe cmdargs as referentially impure, but really concise. Concise is nice - I've often been a bit annoyed that the otherwise nice GetOpt stuff forces me to write a lot of boilerplate, enough of it that my programs usually have a separate Options module. For a lazy slob like me, this means I often just hack something on top of the raw GetArgs or write half-baked but simple solutions like my simpleargs library. 'def' is the default value, empty has a particular semantic meaning and serves to change the options. I should document this more carefully. Perhaps empty should be renamed 'optional', since that's what it does. 'whenMissing'? 'unspecified'? - As I wanted a single file argument, I tried to use 'args' in combination with a parameter of type FilePath. Apparently 'args' wants [FilePath] and appends command line arguments to the default value. Spoilt by Haskell, I'd have expected a type error here. argPos 0 should do the trick. Right. Will subsequent arguments be ignored? CmdArgs is very much a 0.1 release. The documentation isn't polished, it does simple arguments nicely, but has flaws when you try and go more advanced. I want to spend some more time on it at some point. That's great, I'm looking forward to it. -k -- If I haven't seen further, it is by standing in the footprints of giants ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Typed Configuration Files
Magnus Therning mag...@therning.org writes: Seriously, cmdargs is *brilliant*. It's also magic (to me). On this list, I'm uncertain whether brilliant is a warning or a recommendation, but magic is clearly irresistible, so I had a go at using cmdargs. And I agree, it is really nice in quickly and succintly getting command parsing up and working, and in that it most Works As Expected (tm). Some snags I ran into, which may (or may not) serve to improve documentation, and which may (or may not) result in some gentle guidande as to preferred solutions rising to the surface: - The examples use 'def' a lot, and I mistakenly thought 'empty' would supply default values. Not so, replace 'def' with the default value and off you go. 'def' seems to be the minimum value for that particular type. - As I wanted a single file argument, I tried to use 'args' in combination with a parameter of type FilePath. Apparently 'args' wants [FilePath] and appends command line arguments to the default value. I used 'error no file bla bla' as the default value, and appending to this didn't do much good, as you can imagine. So: use [FilePath] and check the length manually. - CmdArgs helpfully provides default --help, --version as well as --quite and --verbose. For the two former, there's also a nice default implementation, but presumably the latter two are for use in the program proper. Unfortunately, I don't know how to get at their values. -k -- If I haven't seen further, it is by standing in the footprints of giants ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Typed Configuration Files
Ketil Malde ke...@malde.org writes: - CmdArgs helpfully provides default --help, --version as well as --quite and --verbose. For the two former, there's also a nice default implementation, but presumably the latter two are for use in the program proper. Unfortunately, I don't know how to get at their values. I couldn't find it in an example, but apparently it is done through global functions 'isLoud', 'isNormal', and 'isQuiet'. -k -- If I haven't seen further, it is by standing in the footprints of giants ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Typed Configuration Files
Hi Sebastian, You might also want to look at how xmonad handles it's configuration. Basically the configuration file is the main-file that produces the executable and takes in the rest of xmonad as a library. This works out quite well, but you need a compiler to update the configuration. Matthias. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Typed Configuration Files
Hi The CmdArgs manual might help: http://community.haskell.org/~ndm/darcs/cmdargs/cmdargs.htm Seriously, cmdargs is *brilliant*. It's also magic (to me). On this list, I'm uncertain whether brilliant is a warning or a recommendation, but magic is clearly irresistible, so I had a go at using cmdargs. I'd describe cmdargs as referentially impure, but really concise. And I agree, it is really nice in quickly and succintly getting command parsing up and working, and in that it most Works As Expected (tm). Some snags I ran into, which may (or may not) serve to improve documentation, and which may (or may not) result in some gentle guidande as to preferred solutions rising to the surface: - The examples use 'def' a lot, and I mistakenly thought 'empty' would supply default values. Not so, replace 'def' with the default value and off you go. 'def' seems to be the minimum value for that particular type. 'def' is the default value, empty has a particular semantic meaning and serves to change the options. I should document this more carefully. Perhaps empty should be renamed 'optional', since that's what it does. - As I wanted a single file argument, I tried to use 'args' in combination with a parameter of type FilePath. Apparently 'args' wants [FilePath] and appends command line arguments to the default value. I used 'error no file bla bla' as the default value, and appending to this didn't do much good, as you can imagine. So: use [FilePath] and check the length manually. argPos 0 should do the trick. - CmdArgs helpfully provides default --help, --version as well as --quite and --verbose. For the two former, there's also a nice default implementation, but presumably the latter two are for use in the program proper. Unfortunately, I don't know how to get at their values. As you found later, isLoud etc do the job. CmdArgs is very much a 0.1 release. The documentation isn't polished, it does simple arguments nicely, but has flaws when you try and go more advanced. I want to spend some more time on it at some point. Thanks, Neil ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Typed Configuration Files
Is there something similar for parsing config files?
If you write one I most certainly will use it! ;)
You (we) can already start using the cmdargs package to parse config
files.
Upon my feature request to add a function to the cmdargs package that
allows to add default arguments, Neil pointed out that the function
System.Environment.withArgs can be used to get the same effect without
changes to the cmdargs package.
Here is a complete example:
{-# LANGUAGE DeriveDataTypeable #-}
import System.Environment
import System.Console.CmdArgs
data Conf = Conf { option :: Bool }
deriving (Show,Data,Typeable)
myConf = mode $ Conf { option = enum False [True,False] }
main = print = getConfig my.conf My Program v0.0 myConf
getConfig configFileName welcomeMsg modeDesc =
do originalArgs - getArgs
argsFromFile - words `fmap` readFile configFileName
withArgs (argsFromFile ++ originalArgs) (cmdArgs welcomeMsg
[modeDesc])
If you save the String '--true' in the file 'my.conf', this program
reads the config from the file and prints it:
# runhaskell typed-config.hs
Conf {option = True}
You can overwrite the default behaviour with command line arguments:
# runhaskell typed-config.hs --false
Conf {option = False}
After parsing a config file into command-line arguments, the parsing
of the typed `Config` comes for free.
Sebastian
P.S.:
Instead of the `words` function one would use some smarter function
that translates real config files into command-line arguments, but the
fez-conf package (which provides such functionality) segfaults on my
computer.
Depending on how one specifies the mode value, one may not be able to
overwrite default options. For example, the usual translation of the
boolean field above is a single flag --option that can be present or
absent. I did not find a way to unset a set flag other than declaring
it as an enum flag. This could be improved if flags without arguments
would support optional arguments like '--option=yes/no' or similar.
(Btw. the documentation of enum seems wrong, the given example does
not typecheck).
--
Underestimating the novelty of the future is a time-honored tradition.
(D.G.)
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[Haskell-cafe] Typed Configuration Files
Dear Café, Neil Mitchell's cmdargs package [1] is pretty neat. It can be used to parse command-line arguments into a user-defined data structure. Is there something similar for parsing config files? There are a number of config file parsers on Hackage. But even the most sophisticated one I found, ConfigFile by John Goerzen [2], only yields primitive data like strings, booleans, and numbers. Did I overlook something? I'd like to write something like do fc - configFile ... ac - cmdArgs ... let conf = fc `mappend` ac where the type of `conf` is a user defined monoid. I found that the fez-conf package [3] provides a function `parseToArgs` which creates a list similar to the one returned by `System.getArgs` from a config file. Neil, if you would add a function to your cmdargs package that allows to specify the argument list, then one could reuse your machinery to create typed config data from config files too, right? Maybe along the lines of do args - parseToArgs $ readFile /my/conf conf - cmdArgsWithDefault args My Program [myMode] The new function `cmdArgsWithDefault` could require the return type to be a monoid in order to allow users to specify themselves how to deal with multiple options of the same kind. Would that be reasonable or is there a better alternative? Cheers, Sebastian [1] http://hackage.haskell.org/package/cmdargs [2] http://hackage.haskell.org/package/ConfigFile [3] http://hackage.haskell.org/package/fez-conf -- Underestimating the novelty of the future is a time-honored tradition. (D.G.) ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Typed Configuration Files
On Fri, Jan 8, 2010 at 12:53 PM, Sebastian Fischer s...@informatik.uni-kiel.de wrote: Dear Café, Neil Mitchell's cmdargs package [1] is pretty neat. It can be used to parse command-line arguments into a user-defined data structure. Is there something similar for parsing config files? If you write one I most certainly will use it! ;) Seriously, cmdargs is *brilliant*. It's also magic (to me). Implementing a config parser in a similar way would likely dispell the magic... if I only could find the time. /M -- Magnus Therning(OpenPGP: 0xAB4DFBA4) magnus＠therning．org Jabber: magnus＠therning．org http://therning.org/magnus identi.ca|twitter: magthe ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Typed Configuration Files
Excerpts from Magnus Therning's message of Fri Jan 08 16:25:31 +0100 2010: On Fri, Jan 8, 2010 at 12:53 PM, Sebastian Fischer s...@informatik.uni-kiel.de wrote: Dear Café, Neil Mitchell's cmdargs package [1] is pretty neat. It can be used to parse command-line arguments into a user-defined data structure. Is there something similar for parsing config files? If you write one I most certainly will use it! ;) Seriously, cmdargs is *brilliant*. It's also magic (to me). Not only to you in fact it is black magic since it uses unsafePerformIO :( -- Nicolas Pouillard http://nicolaspouillard.fr ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Typed Configuration Files
Hi, Seriously, cmdargs is *brilliant*. It's also magic (to me). Not only to you in fact it is black magic since it uses unsafePerformIO :( The problem isn't that it's black magic or that it uses unsafePerformIO - the problem is that it's horribly impure, so doesn't obey referential transparency. Unfortunately this in unavoidable with the way I wanted to write command line arguments... Thanks, Neil ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Typed Configuration Files
Hello Sebastian, Friday, January 8, 2010, 3:53:53 PM, you wrote: Neil Mitchell's cmdargs package [1] is pretty neat. It can be used to parse command-line arguments into a user-defined data structure. Is there something similar for parsing config files? Lua language may be used to describe arbitrarily complex data structure and there is HsLua: http://www.haskell.org/haskellwiki/HsLua -- Best regards, Bulatmailto:bulat.zigans...@gmail.com ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
