-- Hoogle documentation, generated by Haddock
-- See Hoogle, http://www.haskell.org/hoogle/
-- | Command line argument processing
--
-- An easy way to define command line parsers. The two key features are:
-- 1) It's very concise to use, up to three times shorter than getopt. 2)
-- It supports programs with multiple modes (e.g. darcs or cabal).
@package cmdargs
@version 0.1
-- | This module provides simple command line argument processing. The main
-- function of interest is cmdArgs. A simple example is:
--
--
-- data Sample = Sample {hello :: String} deriving (Show, Data, Typeable)
--
--
--
-- sample = mode $ Sample{hello = def &= text "World argument" & empty "world"}
--
--
--
-- main = print =<< cmdArgs "Sample v1, (C) Neil Mitchell 2009" [sample]
--
--
-- Attributes are used to control a number of behaviours:
--
--
module System.Console.CmdArgs
-- | The main entry point for programs using CmdArgs. For an example see
-- System.Console.CmdArgs.
cmdArgs :: (Data a) => String -> [Mode a] -> IO a
-- | Extract the default value from inside a Mode.
modeValue :: Mode a -> a
-- | Construct a Mode from a value annotated with attributes.
mode :: (Data a) => a -> Mode a
data Mode a
-- | Add attributes to a value. Always returns the first argument, but has
-- a non-pure effect on the environment. Take care when performing
-- program transformations.
--
--
-- value &= attrib1 & attrib2
--
(&=) :: a -> Attrib -> a
-- | Combine two attributes.
(&) :: Attrib -> Attrib -> Attrib
-- | Attributes to modify the behaviour.
data Attrib
-- | Flag/Mode: Descriptive text used in the help output.
--
--
-- {str = def &= text "Help message"}
-- -s --str=VALUE Help message
--
text :: String -> Attrib
-- | Flag: The the type of a flag's value, usually upper case. Only used
-- for the help message.
--
--
-- {str = def &= typ "FOO"}
-- -s --str=FOO
--
typ :: String -> Attrib
-- | Flag: Alias for typ "FILE".
typFile :: Attrib
-- | Flag: Alias for typ "DIR".
typDir :: Attrib
-- | Flag: Make the value of a flag optional, using the supplied value if
-- none is given.
--
--
-- {str = def &= empty "foo"}
-- -s --str[=VALUE] (default=foo)
--
empty :: (Show a, Typeable a) => a -> Attrib
-- | Flag: Add flags which trigger this option.
--
--
-- {str = def &= flag "foo"}
-- -s --str --foo=VALUE
--
flag :: String -> Attrib
-- | Flag: A field should not have any flag names guessed for it. All flag
-- names must be specified by flag.
--
--
-- {str = def &= explicit & flag "foo"}
-- --foo=VALUE
--
explicit :: Attrib
-- | Flag: A field is an enumeration of possible values.
--
--
-- data Choice = Yes | No deriving (Data,Typeable,Show,Eq)
-- data Sample = Sample {choice :: Choice}
-- {choice = Yes & enum [Yes &= "say yes", No &= "say no"]}
--
--
--
-- -y --yes say yes (default)
-- -n --no say no
--
enum :: (Typeable a, Eq a, Show a) => a -> [a] -> a
-- | Flag: This field should be used to store the non-flag arguments. Can
-- only be applied to fields of type [String].
--
--
-- {strs = def &= args}
--
args :: Attrib
-- | Flag: This field should be used to store a particular argument
-- position (0-based). Can only be applied to fields of type
-- String.
--
--
-- {str = def &= argPos 0}
--
argPos :: Int -> Attrib
-- | Flag: This field should be used to store all unknown flag arguments.
-- If no unknownFlags field is set, unknown flags raise errors.
-- Can only be applied to fields of type [String].
--
--
-- {strs = def &= unknownFlags}
--
unknownFlags :: Attrib
-- | Mode: This is the name of the program running, used to override the
-- result from getProgName. Only used in the help message.
prog :: String -> Attrib
-- | Mode: Suffix to be added to the help message.
helpSuffix :: [String] -> Attrib
-- | Mode: This mode is the default. If no mode is specified and a mode has
-- this attribute then that mode is selected, otherwise an error is
-- raised.
defMode :: Attrib
-- | Used to test if essential messages should be output to the user.
-- Always true (since even --quiet wants essential messages
-- output). Must be called after cmdArgs.
isQuiet :: IO Bool
-- | Used to test if normal messages should be output to the user. True
-- unless --quiet is specified. Must be called after
-- cmdArgs.
isNormal :: IO Bool
-- | Used to test if helpful debug messages should be output to the user.
-- False unless --verbose is specified. Must be called after
-- cmdArgs.
isLoud :: IO Bool
-- | Format to display help in.
data HelpFormat
-- | As output on the console.
Text :: HelpFormat
-- | Suitable for inclusion in web pages (uses a table rather than explicit
-- wrapping).
HTML :: HelpFormat
-- | Display the help message, as it would appear with --help. The
-- first argument should match the first argument to cmdArgs.
cmdArgsHelp :: String -> [Mode a] -> HelpFormat -> IO String
-- | Class for default values
class Default a
def :: (Default a) => a
-- | The Data class comprehends a fundamental primitive
-- gfoldl for folding over constructor applications, say terms.
-- This primitive can be instantiated in several ways to map over the
-- immediate subterms of a term; see the gmap combinators later
-- in this class. Indeed, a generic programmer does not necessarily need
-- to use the ingenious gfoldl primitive but rather the intuitive
-- gmap combinators. The gfoldl primitive is completed by
-- means to query top-level constructors, to turn constructor
-- representations into proper terms, and to list all possible datatype
-- constructors. This completion allows us to serve generic programming
-- scenarios like read, show, equality, term generation.
--
-- The combinators gmapT, gmapQ, gmapM, etc are all
-- provided with default definitions in terms of gfoldl, leaving
-- open the opportunity to provide datatype-specific definitions. (The
-- inclusion of the gmap combinators as members of class
-- Data allows the programmer or the compiler to derive
-- specialised, and maybe more efficient code per datatype. Note:
-- gfoldl is more higher-order than the gmap combinators.
-- This is subject to ongoing benchmarking experiments. It might turn out
-- that the gmap combinators will be moved out of the class
-- Data.)
--
-- Conceptually, the definition of the gmap combinators in terms
-- of the primitive gfoldl requires the identification of the
-- gfoldl function arguments. Technically, we also need to
-- identify the type constructor c for the construction of the
-- result type from the folded term type.
--
-- In the definition of gmapQx combinators, we use
-- phantom type constructors for the c in the type of
-- gfoldl because the result type of a query does not involve the
-- (polymorphic) type of the term argument. In the definition of
-- gmapQl we simply use the plain constant type constructor
-- because gfoldl is left-associative anyway and so it is readily
-- suited to fold a left-associative binary operation over the immediate
-- subterms. In the definition of gmapQr, extra effort is needed. We use
-- a higher-order accumulation trick to mediate between left-associative
-- constructor application vs. right-associative binary operation (e.g.,
-- (:)). When the query is meant to compute a value of type
-- r, then the result type withing generic folding is r
-- -> r. So the result of folding is a function to which we
-- finally pass the right unit.
--
-- With the -XDeriveDataTypeable option, GHC can generate
-- instances of the Data class automatically. For example, given
-- the declaration
--
-- data T a b = C1 a b | C2 deriving (Typeable, Data)
--
-- GHC will generate an instance that is equivalent to
--
-- instance (Data a, Data b) => Data (T a b) where gfoldl k z (C1
-- a b) = z C1 `k` a `k` b gfoldl k z C2 = z C2 gunfold k z c = case
-- constrIndex c of 1 -> k (k (z C1)) 2 -> z C2 toConstr (C1 _ _) =
-- con_C1 toConstr C2 = con_C2 dataTypeOf _ = ty_T con_C1 = mkConstr ty_T
-- "C1" [] Prefix con_C2 = mkConstr ty_T "C2" [] Prefix ty_T = mkDataType
-- "Module.T" [con_C1, con_C2]
--
-- This is suitable for datatypes that are exported transparently.
class (Typeable a) => Data a
-- | The class Typeable allows a concrete representation of a type
-- to be calculated.
class Typeable a
instance Eq HelpFormat
instance Ord HelpFormat
instance Show HelpFormat
instance Read HelpFormat
instance Enum HelpFormat
instance Bounded HelpFormat
instance Default Double
instance Default Float
instance Default Integer
instance Default Int
instance Default [a]
instance Default Bool