Smart constructor for ProgramInfo.

piHelpHeader and piHelpFooter are set to Nothing. The function piValidateConfiguration is set to const (return [])

Program Description

Help header

Help footer

Options parser for configuration

Default configuration

A validation function. The type in the MonadWriter is excpected to be a Foldable structure for collecting warnings.

Smart constructor for ProgramInfo.

piHelpHeader and piHelpFooter are set to Nothing.

Validation Function

The Right result is interpreted as a Foldable structure of warnings.

A newtype wrapper around a validation function. The only purpose of this type is to avoid ImpredicativeTypes when storing the function in the ProgramInfoValidate record.

Lens for simultaneous query and update of piOptionParser and piDefaultConfiguration. This supports to change the type of ProgramInfo with over and set.

Run an IO action with a configuration that is obtained by updating the given default configuration the values defined via command line arguments.

In addition to the options defined by the given options parser the following options are recognized:

--config-file, -c

Parse the given file path as a (partial) configuration in YAML format.

--print-config, -p

Print the final parsed configuration to standard out and exit.

--help, -h

Print a help message and exit.

Information about the cabal package. The format is:

(info message, detailed info message, version string, license text)

See the documentation of Configuration.Utils.Setup for a way how to generate this information automatically from the package description during the build process.

Run an IO action with a configuration that is obtained by updating the given default configuration the values defined via command line arguments.

In addition to the options defined by the given options parser the following options are recognized:

--config-file, -c

Parse the given file path as a (partial) configuration in YAML format.

--print-config, -p

Print the final parsed configuration to standard out and exit.

--help, -h

Print a help message and exit.

--version, -v

Print the version of the application and exit.

--info, -i

Print a short info message for the application and exit.

--long-info

Print a detailed info message for the application and exit.

--license

Print the text of the lincense of the application and exit.

Parse the command line arguments.

Any warnings from the configuration function are discarded. The options --print-config and --help are just ignored.

NOTE this that this function may call unsafePerformIO for reading configuration files.

Type of option parsers that yield a modification function.

An operator for applying a setter to an option parser that yields a value.

Example usage:

data Auth = Auth
    { _user ∷ !String
    , _pwd ∷ !String
    }

user ∷ Functor φ ⇒ (String → φ String) → Auth → φ Auth
user f s = (\u → s { _user = u }) <$> f (_user s)

pwd ∷ Functor φ ⇒ (String → φ String) → Auth → φ Auth
pwd f s = (\p → s { _pwd = p }) <$> f (_pwd s)

-- or with lenses and TemplateHaskell just:
-- $(makeLenses ''Auth)

pAuth ∷ MParser Auth
pAuth = id
   <$< user .:: strOption
       × long "user"
       ⊕ short 'u'
       ⊕ help "user name"
   <*< pwd .:: strOption
       × long "pwd"
       ⊕ help "password for user"

An operator for applying a setter to an option parser that yields a modification function.

Example usage:

data HttpURL = HttpURL
    { _auth ∷ !Auth
    , _domain ∷ !String
    }

auth ∷ Functor φ ⇒ (Auth → φ Auth) → HttpURL → φ HttpURL
auth f s = (\u → s { _auth = u }) <$> f (_auth s)

domain ∷ Functor φ ⇒ (String → φ String) → HttpURL → φ HttpURL
domain f s = (\u → s { _domain = u }) <$> f (_domain s)

path ∷ Functor φ ⇒ (String → φ String) → HttpURL → φ HttpURL
path f s = (\u → s { _path = u }) <$> f (_path s)

-- or with lenses and TemplateHaskell just:
-- $(makeLenses ''HttpURL)

pHttpURL ∷ MParser HttpURL
pHttpURL = id
    <$< auth %:: pAuth
    <*< domain .:: strOption
        × long "domain"
        ⊕ short 'd'
        ⊕ help "HTTP domain"

The boolOption is an alternative to switch.

Using switch with command line parsers that overwrite settings from a configuration file is problematic: the absence of the switch is interpreted as setting the respective configuration value to False. So there is no way to specify on the command line that the value from the configuration file shall be used. Some command line UIs use two different options for those values, for instance --enable-feature and --disable-feature. This option instead expects a Boolean value. Beside that it behaves like any other option.

A JSON Value parser for a property of a given Object that updates a setter with the parsed value.

data Auth = Auth
    { _userId ∷ !Int
    , _pwd ∷ !String
    }

userId ∷ Functor φ ⇒ (Int → φ Int) → Auth → φ Auth
userId f s = (\u → s { _userId = u }) <$> f (_userId s)

pwd ∷ Functor φ ⇒ (String → φ String) → Auth → φ Auth
pwd f s = (\p → s { _pwd = p }) <$> f (_pwd s)

-- or with lenses and TemplateHaskell just:
-- $(makeLenses ''Auth)

instance FromJSON (Auth → Auth) where
    parseJSON = withObject "Auth" $ \o → id
        <$< setProperty user "user" p o
        <*< setProperty pwd "pwd" parseJSON o
      where
        p = withText "user" $ \case
            "alice" → pure (0 ∷ Int)
            "bob" → pure 1
            e → fail $ "unrecognized user " ⊕ e

A variant of the setProperty that uses the default parseJSON method from the FromJSON instance to parse the value of the property. Its usage pattern mimics the usage pattern of the .: operator from the aeson library.

data Auth = Auth
    { _user ∷ !String
    , _pwd ∷ !String
    }

user ∷ Functor φ ⇒ (String → φ String) → Auth → φ Auth
user f s = (\u → s { _user = u }) <$> f (_user s)

pwd ∷ Functor φ ⇒ (String → φ String) → Auth → φ Auth
pwd f s = (\p → s { _pwd = p }) <$> f (_pwd s)

-- or with lenses and TemplateHaskell just:
-- $(makeLenses ''Auth)

instance FromJSON (Auth → Auth) where
    parseJSON = withObject "Auth" $ \o → id
        <$< user ..: "user" × o
        <*< pwd ..: "pwd" × o

This operator requires that a value is explicitly provided in a configuration file, thus preventing the default value from being used. Otherwise this operator does the same as '(..:)'.

A variant of the aeson operator .: that creates a parser that modifies a setter with a parsed function.

data HttpURL = HttpURL
    { _auth ∷ !Auth
    , _domain ∷ !String
    }

auth ∷ Functor φ ⇒ (Auth → φ Auth) → HttpURL → φ HttpURL
auth f s = (\u → s { _auth = u }) <$> f (_auth s)

domain ∷ Functor φ ⇒ (String → φ String) → HttpURL → φ HttpURL
domain f s = (\u → s { _domain = u }) <$> f (_domain s)

path ∷ Functor φ ⇒ (String → φ String) → HttpURL → φ HttpURL
path f s = (\u → s { _path = u }) <$> f (_path s)

-- or with lenses and TemplateHaskell just:
-- $(makeLenses ''HttpURL)

instance FromJSON (HttpURL → HttpURL) where
    parseJSON = withObject "HttpURL" $ \o → id
        <$< auth %.: "auth" × o
        <*< domain ..: "domain" × o

This operator is an alternative for $ with a higher precedence. It is suitable for usage within applicative style code without the need to add parenthesis.

This operator is a UTF-8 version of % which is an alternative for $ with a higher precedence. It is suitable for usage within applicative style code without the need to add parenthesis.

The hex value of the UTF-8 character × is 0x00d7.

In VIM type: Ctrl-V u 00d7

You may also define a key binding by adding something like the following line to your vim configuration file:

iabbrev <buffer> >< ×

Functional composition for applicative functors.

Functional composition for applicative functors with its arguments flipped.

Applicative functional composition between a pure function and an applicative function.

Applicative functional composition between a pure function and an applicative function with its arguments flipped.

Functional composition for applicative functors.

This is a rather popular operator. Due to conflicts (for instance with the lens package) it may have to be imported qualified.

For people who like nicely aligned code and do not mind messing with editor key-maps: here a version of <.> that uses a unicode symbol

The hex value of the UTF-8 character ⊙ is 0x2299.

A convenient VIM key-map is:

iabbrev <buffer> ../ ⊙

This is the same type as the type from the lens library with the same name.

In case it is already import from the lens package this should be hidden from the import.

This is the same type as the type from the lens library with the same name.

In case it is already import from the lens package this should be hidden from the import.

Commandline parser for record Maybe values

Example:

data Setting = Setting
    { _setA ∷ !Int
    , _setB ∷ !String
    }
    deriving (Show, Read, Eq, Ord, Typeable)

$(makeLenses ''Setting)

defaultSetting ∷ Setting
defaultSetting = Setting
    { _setA = 0
    , _setB = 1
    }

instance ToJSON Setting where
    toJSON setting = object
       [ "a" .= _setA setting
       , "b" .= _setB setting
       ]

instance FromJSON (Setting → Setting) where
    parseJSON = withObject "Setting" $ \o → id
        <$< setA ..: "a" % o
        <*< setB ..: "b" % o

instance FromJSON Setting where
   parseJSON v = parseJSON v <*> pure defaultSetting

pSetting ∷ MParser Setting
pSetting = id
    <$< setA .:: option auto
        % short 'a'
        <> metavar "INT"
        <> help "set a"
    <*< setB .:: option auto
        % short 'b'
        <> metavar "INT"
        <> help "set b"

-- | Use 'Setting' as 'Maybe' in a configuration:
--
data Config = Config
    { _maybeSetting ∷ !(Maybe Setting)
    }
    deriving (Show, Read, Eq, Ord, Typeable)

$(makeLenses ''Config)

defaultConfig ∷ Config
defaultConfig = Config
    { _maybeSetting = defaultSetting
    }

instance ToJSON Config where
    toJSON config = object
        [ "setting" .= maybeSetting
        ]

instance FromJSON (Config → Config) where
    parseJSON = withObject "Config" $ \o → id
        <$< maybeSetting %.: "setting" % o

pConfig ∷ MParser Config
pConfig = id
    <$< maybeSetting %:: (maybeOption defaultSetting
        <$> pEnableSetting
        <*> pSetting)
  where
    pEnableSetting = boolOption
        % long "setting-enable"
        <> value False
        <> help "Enable configuration flags for setting"