Options.Applicative.Extra

helper :: forall a. Parser (a -> a)

A hidden "helper" option which always fails. Use this to add the --help flag to your CLI parser

A common usage pattern is to apply this applicatively when creating a 'ParserInfo'

opts :: ParserInfo Sample opts = info (sample <**> helper) mempty

hsubparser :: forall a. Mod CommandFields a -> Parser a

Builder for a command parser with a "helper" option attached. Used in the same way as subparser, but includes a --help|-h inside the subcommand.

execParser :: forall a. ParserInfo a -> Effect a

Run a program description.

Parse command line arguments. Display help text and exit if any parse error occurs.

customExecParser :: forall a. ParserPrefs -> ParserInfo a -> Effect a

Run a program description with custom preferences.

execParserPure :: forall a. ParserPrefs -> ParserInfo a -> Array String -> ParserResult a

The most general way to run a program description in pure code.

getParseResult :: forall a. ParserResult a -> Maybe a

Extract the actual result from a ParserResult value.

This function returns 'Nothing' in case of errors. Possible error messages or completion actions are simply discarded.

If you want to display error messages and invoke completion actions appropriately, use 'handleParseResult' instead.

handleParseResult :: forall a. ParserResult a -> Effect a

Handle ParserResult.

parserFailure :: forall a. ParserPrefs -> ParserInfo a -> ParseError -> Array Context -> ParserFailure ParserHelp

Generate a ParserFailure from a ParseError in a given Context.

This function can be used, for example, to show the help text for a parser:

handleParseResult <<< Failure $ parserFailure pprefs pinfo ShowHelpText mempty

renderFailure :: ParserFailure ParserHelp -> String -> Tuple String ExitCode