Safe Haskell	Safe
Language	Haskell98

Options.Applicative.Common

Contents

Option parsers
Program descriptions
Running parsers
Low-level utilities

Synopsis

Option parsers

A Parser is composed of a list of options. Several kinds of options are supported:

Flags: simple no-argument options. When a flag is encountered on the command line, its value is returned.
Options: options with an argument. An option can define a reader, which converts its argument from String to the desired value, or throws a parse error if the argument does not validate correctly.
Arguments: positional arguments, validated in the same way as option arguments.
Commands. A command defines a completely independent sub-parser. When a command is encountered, the whole command line is passed to the corresponding parser.

data Parser a Source #

A Parser a is an option parser returning a value of type a.

Instances

Functor Parser Source #
Methods fmap :: (a -> b) -> Parser a -> Parser b # (<$) :: a -> Parser b -> Parser a #
Applicative Parser Source #
Methods pure :: a -> Parser a # (<>) :: Parser (a -> b) -> Parser a -> Parser b # (>) :: Parser a -> Parser b -> Parser b # (<*) :: Parser a -> Parser b -> Parser a #
Alternative Parser Source #
Methods empty :: Parser a # (<\|>) :: Parser a -> Parser a -> Parser a # some :: Parser a -> Parser [a] # many :: Parser a -> Parser [a] #

liftOpt :: Option a -> Parser a Source #

Create a parser composed of a single option.

showOption :: OptName -> String Source #

Program descriptions

data ParserInfo a Source #

A full description for a runnable Parser for a program.

Constructors

ParserInfo

Fields

infoParser :: Parser a
the option parser for the program
infoFullDesc :: Bool
whether the help text should contain full documentation
infoProgDesc :: Chunk Doc
brief parser description
infoHeader :: Chunk Doc
header of the full parser description
infoFooter :: Chunk Doc
footer of the full parser description
infoFailureCode :: Int
exit code for a parser failure
infoIntersperse :: Bool
allow regular options and flags to occur after arguments (default: True)

Instances

Functor ParserInfo Source #
Methods fmap :: (a -> b) -> ParserInfo a -> ParserInfo b # (<$) :: a -> ParserInfo b -> ParserInfo a #

data ParserPrefs Source #

Global preferences for a top-level Parser.

Constructors

ParserPrefs

Fields

prefMultiSuffix :: String
metavar suffix for multiple options
prefDisambiguate :: Bool
automatically disambiguate abbreviations (default: False)
prefShowHelpOnError :: Bool
always show help text on parse errors (default: False)
prefShowHelpOnEmpty :: Bool
show the help text for a command or subcommand if it fails with no input (default: False)
prefBacktrack :: Bool
backtrack to parent parser when a subcommand fails (default: True)
prefColumns :: Int
number of columns in the terminal, used to format the help page (default: 80)

Instances

Eq ParserPrefs Source #
Methods (==) :: ParserPrefs -> ParserPrefs -> Bool # (/=) :: ParserPrefs -> ParserPrefs -> Bool #
Show ParserPrefs Source #
Methods showsPrec :: Int -> ParserPrefs -> ShowS # show :: ParserPrefs -> String # showList :: [ParserPrefs] -> ShowS #

Running parsers

runParserInfo :: MonadP m => ParserInfo a -> Args -> m a Source #

runParserFully :: MonadP m => ArgPolicy -> Parser a -> Args -> m a Source #

runParser :: MonadP m => ArgPolicy -> IsCmdStart -> Parser a -> Args -> m (a, Args) Source #

Apply a Parser to a command line, and return a result and leftover arguments. This function returns an error if any parsing error occurs, or if any options are missing and don't have a default value.

evalParser :: Parser a -> Maybe a Source #

The default value of a Parser. This function returns an error if any of the options don't have a default value.

Low-level utilities

mapParser :: (forall x. OptHelpInfo -> Option x -> b) -> Parser a -> [b] Source #

Map a polymorphic function over all the options of a parser, and collect the results in a list.

treeMapParser :: (forall x. OptHelpInfo -> Option x -> b) -> Parser a -> OptTree b Source #

Like mapParser, but collect the results in a tree structure.

optionNames :: OptReader a -> [OptName] Source #