cmdargs-0.10.13: Command line argument processing

Safe Haskell | None
Language | Haskell98

System.Console.CmdArgs.Implicit

Contents

- Running command lines
- Constructing command lines
  - Impure
  - Pure
- Re-exported for convenience

Description

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 = Sample{hello = def &= help "World argument" &= opt "world"}
             &= summary "Sample v1"

    main = print =<< cmdArgs sample

Attributes are used to control a number of behaviours:

- The help message: `help`, `typ`, `details`, `summary`, `program`, `groupname`
- Flag behaviour: `opt`, `enum`, `verbosity`, `ignore`
- Flag name assignment: `name`, `explicit`
- Controlling non-flag arguments: `args`, `argPos`
- multi-mode programs: `modes`, `auto`

Supported Types: Each field in the record must be one of the supported atomic types (`String`, `Int`, `Integer`, `Float`, `Double`, `Bool`, an enumeration, a tuple of atomic types) or a list (`[]`) or `Maybe` wrapping at atomic type.

Missing Fields: If a field is shared by multiple modes, it may be omitted in subsequent modes, and will default to the previous value.

Purity: Values created with annotations are not pure - the first time they are computed they will include the annotations, but subsequently they will not. If you wish to run the above example in a more robust way:

    sample = cmdArgsMode $ Sample{hello = ... -- as before

    main = print =<< cmdArgsRun sample

Even using this scheme, sometimes GHC's optimisations may share values who have the same annotation. To disable sharing you may need to specify `{-# OPTIONS_GHC -fno-cse #-}` in the module you define the flags.

Pure annotations: Alternatively, you may use pure annotations, which are referentially transparent, but less type safe and more verbose. The initial example may be written as:

`sample = `record` Sample{} [hello := `def` `+=` `help` "World argument" `+=` `opt` "world"]` ``+=` `summary` "Sample v1"`

    main = print =<< (cmdArgs_ sample :: IO Sample)

All the examples are written using impure annotations. To convert to pure annotations follow the rules:

    Ctor {field1 = value1 &= ann1, field2 = value2} &= ann2 ==> record Ctor{} [field1 := value1 += ann1, field2 := value2] += ann2
    Ctor (value1 &= ann1) value2 &= ann2 ==> record Ctor{} [atom value1 += ann1, atom value2] += ann2
    modes [Ctor1{...}, Ctor2{...}] ==> modes_ [record Ctor1{} [...], record Ctor2{} [...]]
    Ctor {field1 = enum [X &= ann, Y]} ==> record Ctor{} [enum_ field1 [atom X += ann, atom Y]]

If you are willing to use TemplateHaskell, you can write in the impure syntax, but have your code automatically translated to the pure style. For more details see System.Console.CmdArgs.Quote.

Synopsis

- cmdArgs :: Data a => a -> IO a
- cmdArgsMode :: Data a => a -> Mode (CmdArgs a)
- cmdArgsRun :: Mode (CmdArgs a) -> IO a
- cmdArgs_ :: Data a => Annotate Ann -> IO a
- cmdArgsMode_ :: Data a => Annotate Ann -> Mode (CmdArgs a)
- cmdArgsApply :: CmdArgs a -> IO a
- data CmdArgs a = CmdArgs {
  - cmdArgsValue :: a
  - cmdArgsHelp :: Maybe String
  - cmdArgsVersion :: Maybe String
  - cmdArgsVerbosity :: Maybe Verbosity
  - cmdArgsPrivate :: CmdArgsPrivate
  }
- opt :: (Show a, Typeable a) => a -> Ann
- typ :: String -> Ann
- typFile :: Ann
- typDir :: Ann
- help :: String -> Ann
- name :: String -> Ann
- args :: Ann
- argPos :: Int -> Ann
- groupname :: String -> Ann
- details :: [String] -> Ann
- summary :: String -> Ann
- auto :: Ann
- program :: String -> Ann
- explicit :: Ann
- ignore :: Ann
- verbosity :: Ann
- helpArg :: [Ann] -> Ann
- versionArg :: [Ann] -> Ann
- verbosityArgs :: [Ann] -> [Ann] -> Ann
- noAtExpand :: Ann
- (&=) :: Data val => val -> Ann -> val
- modes :: Data val => [val] -> val
- enum :: Data val => [val] -> val
- (+=) :: Annotate ann -> ann -> Annotate ann
- record :: Data a => a -> [Annotate ann] -> Annotate ann
- atom :: Data val => val -> Annotate ann
- data Annotate ann = forall c f . (Data c, Data f) => (c -> f) := f
- enum_ :: (Data c, Data f) => (c -> f) -> [Annotate Ann] -> Annotate Ann
- modes_ :: [Annotate Ann] -> Annotate Ann
- module System.Console.CmdArgs.Verbosity
- module System.Console.CmdArgs.Default
- data Ann
- data Mode a
- class Typeable * a => Data a
- class Typeable a

# Running command lines

cmdArgs :: Data a => a -> IO a

Take impurely annotated records and run the corresponding command line. Shortcut for ``cmdArgsRun` . `cmdArgsMode``.

To use `cmdArgs` with custom command line arguments see `withArgs`.

cmdArgsMode :: Data a => a -> Mode (CmdArgs a)

Take impurely annotated records and turn them in to a `Mode` value, that can make use of the System.Console.CmdArgs.Explicit functions (i.e. `process`).

Annotated records are impure, and will only contain annotations on their first use. The result of this function is pure, and can be reused.

cmdArgsRun :: Mode (CmdArgs a) -> IO a

Run a Mode structure. This function reads the command line arguments and then performs as follows:

- If invalid arguments are given, it will display the error message and exit.
- If `--help` is given, it will display the help message and exit.
- If `--version` is given, it will display the version and exit.
- In all other circumstances the program will return a value.
- Additionally, if either `--quiet` or `--verbose` is given (see `verbosity`) it will set the verbosity (see `setVerbosity`).

cmdArgs_ :: Data a => Annotate Ann -> IO a

Take purely annotated records and run the corresponding command line. Shortcut for ``cmdArgsRun` . `cmdArgsMode_``.

To use `cmdArgs_` with custom command line arguments see `withArgs`.

cmdArgsMode_ :: Data a => Annotate Ann -> Mode (CmdArgs a)

Take purely annotated records and turn them in to a `Mode` value, that can make use of the System.Console.CmdArgs.Explicit functions (i.e. `process`).

cmdArgsApply :: CmdArgs a -> IO a

Perform the necessary actions dictated by a `CmdArgs` structure.

- If `cmdArgsHelp` is `Just`, it will display the help message and exit.
- If `cmdArgsVersion` is `Just`, it will display the version and exit.
- In all other circumstances it will return a value.
- Additionally, if `cmdArgsVerbosity` is `Just` (see `verbosity`) it will set the verbosity (see `setVerbosity`).

data CmdArgs a

A structure to store the additional data relating to `--help`, `--version`, `--quiet` and `--verbose`.

Constructors

CmdArgs |
Fields cmdArgsValue :: a The underlying value being wrapped. cmdArgsHelp :: Maybe String `Just` if `--help` is given, then gives the help message for display, including a trailing newline. cmdArgsVersion :: Maybe String `Just` if `--version` is given, then gives the version message for display, including a trailing newline. cmdArgsVerbosity :: Maybe Verbosity `Just` if `--quiet` or `--verbose` is given, then gives the verbosity to use. cmdArgsPrivate :: CmdArgsPrivate Private: Only exported due to Haddock limitations.

Instances

Functor CmdArgs |
Eq a => Eq (CmdArgs a) |
Data a => Data (CmdArgs a) |
Ord a => Ord (CmdArgs a) |
Show a => Show (CmdArgs a) |

# Constructing command lines

Attributes can work on a flag (inside a field), on a mode (outside the record), or on all modes (outside the `modes` call).

opt :: (Show a, Typeable a) => a -> Ann

Flag: "I want users to be able to omit the value associated with this flag."

Make the value of a flag optional. If `--flag` is given, it will be treated as `--flag=this_argument`.

    {hello = def &= opt "foo"}
      -h --hello[=VALUE]    (default=foo)

Note that all flags in CmdArgs are optional, and if omitted will use their default value. Those annotated with `opt` also allow the flag to be present without an associated value. As an example:

    {hello = "DEFAULT" &= opt "OPTIONAL"}

    $ main
    {hello = "DEFAULT"}
    $ main --hello
    {hello = "OPTIONAL"}
    $ main --hello=VALUE
    {hello = "VALUE"}

typ :: String -> Ann

Flag: "For this flag, users need to give something of type ..."

The the type of a flag's value, usually upper case. Only used for the help message. Commonly the type will be `FILE` (`typFile`) or `DIR` (`typDir`).

    {hello = def &= typ "MESSAGE"}
      -h --hello=MESSAGE

typFile :: Ann

Flag: "Users must give a file for this flag's value."

Alias for ``typ` FILE`.

typDir :: Ann

Flag: "Users must give a directory for this flag's value."

Alias for ``typ` DIR`.

help :: String -> Ann

Flag/Mode: "The help message is ..."

Descriptive text used in the help output.

    {hello = def &= help "Help message"}
      -h --hello=VALUE      Help message

name :: String -> Ann

Flag: "Use this flag name for this field."

Add flags which trigger this option.

    {hello = def &= name "foo"}
      -h --hello --foo=VALUE

args :: Ann

Flag: "Put non-flag arguments here."

All argument flags not captured by `argPos` are returned by `args`.

    {hello = def &= args}

argPos :: Int -> Ann

Flag: "Put the nth non-flag argument here."

This field should be used to store a particular argument position (0-based).

    {hello = def &= argPos 0}

groupname :: String -> Ann

Flag/Mode: "Give these flags/modes a group name in the help output."

This mode will be used for all following modes/flags, until the next `groupname`.

    {hello = def &= groupname "Welcomes"}
    Welcomes
      -h --hello=VALUE

details :: [String] -> Ann

Mode: "A longer description of this mode is ..."

Suffix to be added to the help message.

    Sample{..} &= details ["More details on the website www.example.org"]

summary :: String -> Ann

Modes: "My program name/version/copyright is ..."

One line summary of the entire program, the first line of `--help` and the only line of `--version`. If the string contains a version number component will also provide `--numeric-version`.

    Sample{..} &= summary "CmdArgs v0.0, (C) Neil Mitchell 1981"

auto :: Ann

Mode: "If the user doesn't give a mode, use this one."

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.

    modes [Mode1{..}, Mode2{..} &= auto, Mode3{..}]

program :: String -> Ann

Modes: "My program executable is named ..."

This is the name of the program executable. Only used in the help message. Defaults to the type of the mode.

    Sample{..} &= program "sample"

explicit :: Ann

Flag: "Don't guess any names for this field."

A field should not have any flag names guessed for it. All flag names must be specified by `flag`.

    {hello = def &= explicit &= name "foo"}
      --foo=VALUE

ignore :: Ann

Flag/Mode: "Ignore this field, don't let the user set it."

A mode or field is not dealt with by CmdArgs.

    {hello = def, extra = def &= ignore}
      --hello=VALUE

verbosity :: Ann

Modes: "My program needs verbosity flags."

Add `--verbose` and `--quiet` flags.

helpArg :: [Ann] -> Ann

Modes: "Customise the help argument."

Add extra options to a help argument, such as `help`, `name`, `ignore` or `explicit`.

    Sample{..} &= helpArg [explicit, name "h"]

versionArg :: [Ann] -> Ann

Modes: "Customise the version argument."

Add extra options to a version argument, such as `help`, `name`, `ignore`, `summary` or `explicit`.

    Sample{..} &= versionArg [ignore]

verbosityArgs :: [Ann] -> [Ann] -> Ann

Modes: "Customise the verbosity arguments."

Add extra options to a verbosity arguments (`--verbose` and `--quiet`), such as `help`, `name`, `ignore` or `explicit`. The verbose options come first, followed by the quiet options.

    Sample{..} &= verbosityArgs [ignore] [name "silent", explicit]

noAtExpand :: Ann

Program: "Turn off @ expansion."

Usually arguments starting with @ are treated as a file containing a set of arguments. This annotation turns off that behaviour.

    Sample{..} &= noAtExpand

## Impure

(&=) :: Data val => val -> Ann -> val

Add an annotation to a value. Note that if the value is evaluated more than once the annotation will only be available the first time.

modes :: Data val => [val] -> val

Modes: "I want a program with multiple modes, like darcs or cabal."

Takes a list of modes, and creates a mode which includes them all. If you want one of the modes to be chosen by default, see `auto`.

    data Modes = Mode1 | Mode2 | Mode3 deriving Data
    cmdArgs $ modes [Mode1,Mode2,Mode3]

enum :: Data val => [val] -> val

Flag: "I want several different flags to set this one field to different values."

This annotation takes a type which is an enumeration, and provides multiple separate flags to set the field to each value. The first element in the list is used as the value of the field.

    data State = On | Off deriving Data
    data Mode = Mode {state :: State}
    cmdArgs $ Mode {state = enum [On &= help "Turn on",Off &= help "Turn off"]}
      --on   Turn on
      --off  Turn off

This annotation can be used to allow multiple flags within a field:

    data Mode = Mode {state :: [State]}
    cmdArgs $ Mode {state = enum [[] &= ignore, [On] &= help "Turn on", [Off] &= help "Turn off"]}

Now `--on --off` would produce `Mode [On,Off]`.

## Pure

(+=) :: Annotate ann -> ann -> Annotate ann infixl 2

Add an annotation to a value.

record :: Data a => a -> [Annotate ann] -> Annotate ann

Create a constructor/record. The first argument should be the type of field, the second should be a list of fields constructed originally defined by `:=` or `:=+`.

This operation is not type safe, and may raise an exception at runtime if any field has the wrong type or label.

atom :: Data val => val -> Annotate ann

Lift a pure value to an annotation.

data Annotate ann

This type represents an annotated value. The type of the underlying value is not specified.

Constructors

forall c f . (Data c, Data f) => (c -> f) := f infix 3 | Construct a field, `fieldname := value`.

enum_ :: (Data c, Data f) => (c -> f) -> [Annotate Ann] -> Annotate Ann

Like `enum`, but using the pure annotations.

modes_ :: [Annotate Ann] -> Annotate Ann

Like `modes`, but using the pure annotations.

# Re-exported for convenience

Provides a few opaque types (for writing type signatures), verbosity control, default values with `def` and the `Data`/`Typeable` type classes.

module System.Console.CmdArgs.Verbosity

module System.Console.CmdArgs.Default

data Ann

The general type of annotations that can be associated with a value.

Instances

Eq Ann |
Data Ann |
Ord Ann |
Show Ann |

data Mode a

A mode. Do not use the `Mode` constructor directly, instead use `mode` to construct the `Mode` and then record updates. Each mode has three main features:

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

To produce the help information for a mode, either use `helpText` or `show`.

Instances

Remap Mode |

class Typeable * a => Data 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 `gmapQ` x 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.

Minimal complete definition

gunfold, toConstr, dataTypeOf

Instances

Data Bool |
Data Char |
Data Double |
Data Float |
Data Int |
Data Int8 |
Data Int16 |
Data Int32 |
Data Int64 |
Data Integer |
Data Ordering |
Data Word |
Data Word8 |
Data Word16 |
Data Word32 |
Data Word64 |
Data Exp |
Data Match |
Data Clause |
Data Pat |
Data Type |
Data Dec |
Data Name |
Data FunDep |
Data TyVarBndr |
Data () |
Data Version |
Data ModName |
Data PkgName |
Data Module |
Data OccName |
Data NameFlavour |
Data NameSpace |
Data Loc |
Data Info |
Data ModuleInfo |
Data Fixity |
Data FixityDirection |
Data Lit |
Data Body |
Data Guard |
Data Stmt |
Data Range |
Data TySynEqn |
Data FamFlavour |
Data Foreign |
Data Callconv |
Data Safety |
Data Pragma |
Data Inline |
Data RuleMatch |
Data Phases |
Data RuleBndr |
Data AnnTarget |
Data Strict |
Data Con |
Data TyLit |
Data Role |
Data AnnLookup |
Data Ann |
Data Verbosity |
Data a => Data [a] |
(Data a, Integral a) => Data (Ratio a) |
(Data a, Typeable * a) => Data (Ptr a) |
(Data a, Typeable * a) => Data (ForeignPtr a) |
Data a => Data (Identity a) |
Data a => Data (Maybe a) |
Data a => Data (CmdArgs a) |
(Data a, Data b) => Data (Either a b) |
(Data a, Data b) => Data (a, b) |
(Typeable * a, Data a, Data b, Ix a) => Data (Array a b) |
Data t => Data (Proxy * t) |
(Data a, Data b, Data c) => Data (a, b, c) |
(Coercible * a b, Data a, Data b) => Data (Coercion * a b) |
((~) * a b, Data a) => Data ((:~:) * a b) |
(Data a, Data b, Data c, Data d) => Data (a, b, c, d) |
(Data a, Data b, Data c, Data d, Data e) => Data (a, b, c, d, e) |
(Data a, Data b, Data c, Data d, Data e, Data f) => Data (a, b, c, d, e, f) |
(Data a, Data b, Data c, Data d, Data e, Data f, Data g) => Data (a, b, c, d, e, f, g) |

class Typeable a

The class `Typeable` allows a concrete representation of a type to be calculated.

Minimal complete definition

typeRep#