Safe Haskell	Safe-Inferred
Language	Haskell98

Options.Applicative.Extra

Contents

Extra parser utilities

Synopsis

Extra parser utilities

This module contains high-level functions to run parsers.

helper :: Parser (a -> a) Source

A hidden "helper" option which always fails.

hsubparser :: Mod CommandFields a -> Parser a Source

execParser :: ParserInfo a -> IO a Source

Run a program description.

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

execParserMaybe :: ParserInfo a -> [String] -> Maybe a Source

Deprecated: Use execParserPure together with getParseResult instead

Run a program description in pure code.

This function behaves like execParser, but can be called from pure code. Note that, in case of errors, no message is displayed, and this function simply returns Nothing.

If you need to keep track of error messages, use execParserPure instead.

customExecParser :: ParserPrefs -> ParserInfo a -> IO a Source

Run a program description with custom preferences.

customExecParserMaybe :: ParserPrefs -> ParserInfo a -> [String] -> Maybe a Source

Deprecated: Use execParserPure together with getParseResult instead

Run a program description with custom preferences in pure code.

See execParserMaybe for details.

execParserPure Source

Arguments

:: ParserPrefs	Global preferences for this parser
-> ParserInfo a	Description of the program to run
-> [String]	Program arguments
-> ParserResult a

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

getParseResult :: ParserResult a -> Maybe a Source

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 :: ParserResult a -> IO a Source

Handle ParserResult.

parserFailure :: ParserPrefs -> ParserInfo a -> ParseError -> Context -> ParserFailure ParserHelp Source

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 -> (String, ExitCode) Source

newtype ParserFailure h Source

Constructors

ParserFailure
Fields execFailure :: String -> (h, ExitCode, Int)

Instances

Functor ParserFailure
Show h => Show (ParserFailure h)

overFailure :: (ParserHelp -> ParserHelp) -> ParserResult a -> ParserResult a Source

data ParserResult a Source

Result of execParserPure.

Constructors

Success a
Failure (ParserFailure ParserHelp)
CompletionInvoked CompletionResult

Instances

Monad ParserResult
Functor ParserResult
Applicative ParserResult
Show a => Show (ParserResult 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)
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)

newtype CompletionResult Source

Constructors

CompletionResult
Fields execCompletion :: String -> IO String

Instances

Show CompletionResult