System.Console.CmdArgs.Explicit

Contents

Description

This module constructs command lines. You may either use the helper functions (flagNone, flagOpt, mode etc.) or construct the type directly. These types are intended to give all the necessary power to the person constructing a command line parser.

For people constructing simpler command line parsers, the module System.Console.CmdArgs.Implicit may be more appropriate.

As an example of a parser:

 arguments :: Mode [(String,String)]
 arguments = mode "explicit" [] "Explicit sample program" (flagArg (upd "file") "FILE")
     [flagOpt "world" ["hello","h"] (upd "world") "WHO" "World argument"
     ,flagReq ["greeting","g"] (upd "greeting") "MSG" "Greeting to give"
     ,flagHelpSimple (("help",""):)]
     where upd msg x v = Right $ (msg,x):v

And this can be invoked by:

 main = do
     x <- processArgs arguments
     if ("help","") `elem` xs then
         print $ helpText def arguments
      else
         print x

Groups: The Group structure allows flags/modes to be grouped for the purpose of displaying help. When processing command lines, the group structure is ignored.

Modes: The Explicit module allows multiple mode programs by placing additional modes in modeGroupModes. Every mode is allowed sub-modes, and thus multiple levels of mode may be created. Given a mode x with sub-modes xs, if the first argument corresponds to the name of a sub-mode, then that sub-mode will be applied. If not, then the arguments will be processed by mode x. Consequently, if you wish to force the user to explicitly enter a mode, simply give sub-modes, and leave modeArgs as Nothing. Alternatively, if you want one sub-mode to be selected by default, place all it's flags both in the sub-mode and the outer mode.

Synopsis

Running command lines

process :: Mode a -> [String] -> Either String aSource

Process a list of flags (usually obtained from getArgs) with a mode. Returns Left and an error message if the command line fails to parse, or Right and the associated value.

processValue :: Mode a -> [String] -> aSource

Process a list of flags (usually obtained from getArgs) with a mode. Displays an error and exits with failure if the command line fails to parse, or returns the associated value. Implemeneted in terms of process.

processArgs :: Mode a -> IO aSource

Process the flags obtained by getArgs with a mode. Displays an error and exits with failure if the command line fails to parse, or returns the associated value. Implemented in terms of process.

Constructing command lines

type Name = String Source

A name, either the name of a flag (--foo) or the name of a mode.

type Help = String Source

A help message that goes with either a flag or a mode.

type FlagHelp = String Source

The type of a flag, i.e. --foo=TYPE.

parseBool :: String -> Maybe Bool Source

Parse a boolean, accepts as True: true yes on enabled 1.

data Group a Source

A group of items (modes or flags). The items are treated as a list, but the group structure is used when displaying the help message.

Constructors

Group
Fields groupUnnamed :: [a] Normal items. groupHidden :: [a] Items that are hidden (not displayed in the help message). groupNamed :: [(Help, [a])] Items that have been grouped, along with a description of each group.

Instances

Functor Group
Show a => Show (Group a)
Monoid (Group a)

fromGroup :: Group a -> [a]Source

Convert a group into a list.

toGroup :: [a] -> Group aSource

Convert a list into a group, placing all fields in groupUnnamed.

data Mode a Source

A mode. Each mode has three main features:

A list of submodes (modeGroupModes)
A list of flags (modeGroupFlags)
Optionally an unnamed argument (modeArgs)

Constructors

Mode

Fields

modeGroupModes :: Group (Mode a): The available sub-modes
modeNames :: [Name]: The names assigned to this mode (for the root mode, this name is used as the program name)
modeValue :: a: Value to start with
modeCheck :: a -> Either String a
modeHelp :: Help: Help text
modeHelpSuffix :: [String]: A longer help suffix displayed after a mode
modeArgs :: Maybe (Arg a): An unnamed argument
modeGroupFlags :: Group (Flag a): Groups of flags

Instances

Remap Mode
Show (Mode a)

modeModes :: Mode a -> [Mode a]Source

Extract the modes from a Mode

modeFlags :: Mode a -> [Flag a]Source

Extract the flags from a Mode

data FlagInfo Source

The FlagInfo type has the following meaning:

              FlagReq     FlagOpt      FlagOptRare/FlagNone
 -xfoo        -x=foo      -x=foo       -x= -foo
 -x foo       -x=foo      -x foo       -x= foo
 -x=foo       -x=foo      -x=foo       -x=foo
 --xx foo     --xx=foo    --xx foo     --xx foo
 --xx=foo     --xx=foo    --xx=foo     --xx=foo

Constructors

FlagReq	Required argument
FlagOpt String	Optional argument
FlagOptRare String	Optional argument that requires an = before the value
FlagNone	No argument

Instances

Eq FlagInfo
Ord FlagInfo
Show FlagInfo

fromFlagOpt :: FlagInfo -> String Source

Extract the value from inside a FlagOpt or FlagOptRare, or raises an error.

type Update a = String -> a -> Either String aSource

A function to take a string, and a value, and either produce an error message (Left), or a modified value (Right).

data Flag a Source

A flag, consisting of a list of flag names and other information.

Constructors

Flag
Fields flagNames :: [Name] The names for the flag. flagInfo :: FlagInfo Information about a flag's arguments. flagValue :: Update a The way of processing a flag. flagType :: FlagHelp The type of data for the flag argument, i.e. FILE/DIR/EXT flagHelp :: Help The help message associated with this flag.

Instances

Remap Flag
Show (Flag a)

data Arg a Source

An unnamed argument. Anything not starting with - is considered an argument, apart from "-" which is considered to be the argument "-", and any arguments following "--". For example:

 programname arg1 -j - --foo arg3 -- -arg4 --arg5=1 arg6

Would have the arguments:

 ["arg1","-","arg3","-arg4","--arg5=1","arg6"]

Constructors

Arg
Fields argValue :: Update a A way of processing the argument. argType :: FlagHelp The type of data for the argument, i.e. FILE/DIR/EXT

Instances

Remap Arg
Show (Arg a)

checkMode :: Mode a -> Maybe String Source

Check that a mode is well formed.

class Remap m whereSource

Methods

remap Source

Arguments

:: (a -> b)	Embed a value
-> (b -> (a, a -> b))	Extract the mode and give a way of re-embedding
-> m a
-> m b

Instances

Remap Arg
Remap Flag
Remap Mode

remap2 :: Remap m => (a -> b) -> (b -> a) -> m a -> m bSource

mode :: Name -> a -> Help -> Arg a -> [Flag a] -> Mode aSource

Create a mode with a name, an initial value, some help text, a way of processing arguments and a list of flags.

modes :: String -> a -> Help -> [Mode a] -> Mode aSource

Create a list of modes, with a program name, an initial value, some help text and the child modes.

flagNone :: [Name] -> (a -> a) -> Help -> Flag aSource

Create a flag taking no argument value, with a list of flag names, an update function and some help text.

flagOpt :: String -> [Name] -> Update a -> FlagHelp -> Help -> Flag aSource

Create a flag taking an optional argument value, with an optional value, a list of flag names, an update function, the type of the argument and some help text.

flagReq :: [Name] -> Update a -> FlagHelp -> Help -> Flag aSource

Create a flag taking a required argument value, with a list of flag names, an update function, the type of the argument and some help text.

flagArg :: Update a -> FlagHelp -> Arg aSource

Create an argument flag, with an update function and the type of the argument.

flagBool :: [Name] -> (Bool -> a -> a) -> Help -> Flag aSource

Create a boolean flag, with a list of flag names, an update function and some help text.

flagHelpSimple :: (a -> a) -> Flag aSource

Create a help flag triggered by -?/--help.

flagHelpFormat :: (HelpFormat -> TextFormat -> a -> a) -> Flag aSource

Create a help flag triggered by -?/--help. The user may optionally modify help by specifying the format, such as:

 --help=all          - help for all modes
 --help=html         - help in HTML format
 --help=100          - wrap the text at 100 characters
 --help=100,one      - full text wrapped at 100 characters

flagVersion :: (a -> a) -> Flag aSource

Create a version flag triggered by -V/--version.

flagsVerbosity :: (Verbosity -> a -> a) -> [Flag a]Source

Create verbosity flags triggered by -v/--verbose and -q/--quiet

Displaying help

data HelpFormat Source

Specify the format to output the help.

Constructors

HelpFormatDefault	Equivalent to `HelpFormatAll` if there is not too much text, otherwise `HelpFormatOne`.
HelpFormatOne	Display only the first mode.
HelpFormatAll	Display all modes.

Instances

Bounded HelpFormat
Enum HelpFormat
Eq HelpFormat
Ord HelpFormat
Read HelpFormat
Show HelpFormat
Default HelpFormat

helpText :: HelpFormat -> Mode a -> [Text]Source

Generate a help message from a mode.