-- Hoogle documentation, generated by Haddock
-- See Hoogle, http://www.haskell.org/hoogle/


-- | Command-line parser.
--   
--   This package implements parsing of Plan 9-style command line flags.
@package getflag
@version 1.0


-- | This adaptation of <a>System.Console.GetOpt</a> provides easy handling
--   of classic Unix/Plan 9-style command line options. This means that
--   single dashes are used to prefix option names, which may be of any
--   length (not just single characters, although such is generally
--   recommended). It is not possible to collapse multiple options in a
--   single parameter, so you will have to write <tt>-a -b</tt> instead of
--   <tt>-ab</tt>. A single GNU extension is included: the parameter
--   <tt>--</tt> will cause anything past it to be returned as arguments,
--   not options, even if the parameters have leading dashes.
--   
--   The API is almost compatible with <a>System.Console.GetOpt</a>, the
--   only difference being in <a>OptDescr</a>, which no longer permits
--   multiple names per option.
module System.Console.GetFlag

-- | Process the command-line, and return the list of values that matched
--   (and those that didn't). The arguments are:
--   
--   <ul>
--   <li>The order requirements (see <a>ArgOrder</a>)</li>
--   <li>The option descriptions (see <a>OptDescr</a>)</li>
--   <li>The actual command line arguments (presumably got from
--   <tt>System.Environment.getArgs</tt>).</li>
--   </ul>
--   
--   <a>getOpt</a> returns a triple consisting of the option arguments, a
--   list of non-options, and a list of error messages.
getOpt :: ArgOrder a -> [OptDescr a] -> [String] -> ([a], [String], [String])

-- | This is almost the same as <a>getOpt</a>, but returns a quadruple
--   consisting of the option arguments, a list of non-options, a list of
--   unrecognized options, and a list of error messages.
getOpt' :: ArgOrder a -> [OptDescr a] -> [String] -> ([a], [String], [String], [String])

-- | Return a string describing the usage of a command, derived from the
--   header (first argument) and the options described by the second
--   argument.
usageInfo :: String -> [OptDescr a] -> String

-- | What to do with options following non-options
data ArgOrder a

-- | no option processing after first non-option
RequireOrder :: ArgOrder a

-- | freely intersperse options and non-options
Permute :: ArgOrder a

-- | wrap non-options into options
ReturnInOrder :: (String -> a) -> ArgOrder a

-- | Each <a>OptDescr</a> describes a single option.
--   
--   The arguments to <a>Option</a> are:
--   
--   <ul>
--   <li>the name of the option</li>
--   <li>argument descriptor</li>
--   <li>explanation of option for user</li>
--   </ul>
data OptDescr a
Option :: String -> (ArgDescr a) -> String -> OptDescr a

-- | Describes whether an option takes an argument or not, and if so how
--   the argument is injected into a value of type <tt>a</tt>.
data ArgDescr a

-- | no argument expected
NoArg :: a -> ArgDescr a

-- | option requires argument
ReqArg :: (String -> a) -> String -> ArgDescr a

-- | optional argument
OptArg :: (Maybe String -> a) -> String -> ArgDescr a