Multiarg.Internal

Functions and types used by the Multiarg module. You don't have to worry about "breaking" anything by using this module. This module is separate from Multiarg only because it makes the documentation in that module cleaner, as that module should satisfy most use cases. Use this module if you want more control over error handling, or if you want to process arguments using pure functions rather than IO functions.

Documentation

limelineOutputToParsedCommandLine :: ([Either [Output a] (PosArg a)], Maybe OptName) -> ParsedCommandLine a

data ParsedCommandLine a

Indicates the result of parsing a command line.

Constructors

ParsedCommandLine [Either OptionError a] (Maybe OptName)

ParsedCommandLine a b, where:

a is a list of errors and results, in the original order in which they appeared on the command line.

b is Just p if the user included an option at the end of the command line and there were not enough following words to provide the option with its necessary option arguments, where p is the name of the option with insufficient option arguments; otherwise Nothing.

Instances

Functor ParsedCommandLine

Eq a => Eq (ParsedCommandLine a)

Ord a => Ord (ParsedCommandLine a)

Show a => Show (ParsedCommandLine a)

parsedResults :: ParsedCommandLine a -> Either (String, [String]) [a]

Gets the results from a parsed command line. If there were errors, returns a Left with an error message; otherwise, returns a Right with a list of the results.

insufficientOptArgs :: OptName -> String

optError :: OptionError -> String

parseCommandLinePure

Arguments

:: [OptSpec a]

All program options

-> (String -> a)

Processes non-option positional arguments

-> [String]

Input tokens from the command line, probably obtained from getArgs

-> ParsedCommandLine a

Parses a command line; a pure function (unlike parseCommandLineIO).

parseCommandLine

Arguments

:: (String -> String)

Returns help for your command. This function is applied to the name of the program being run, which is obtained from getProgName. The function should return a string that gives help for how to use your command; this string is printed as-is.

-> [OptSpec a]

All program options. An option for -h and for --help is added for you, using the help function given above. If the user asks for help, then it is printed and the program exits successfully. If the user gives a command line with one or more errors in it, an error message is printed, along with something like Enter program-name --help for help.

-> (String -> a)

Processes positional arguments.

-> IO [a]

Fetches the words from the command line arguments using getArgs and parses them. If there is an error, prints an error message and exits unsuccessfully. Otherwise, returns the parsed result, where each item in the list corresponds to a parsed option or positional argument in the order in which it appeared on the command line.

Parses a command line. Runs in the IO monad so that it can do some tedious things for you:

• fetches the words on command line using getArgs and the name of the program with getProgName
• prints help, if the user requested help, and exits successfully
• prints an error message and exits unsuccessfully, if the user entered a bad command line (such as an unknown option)

If you don't want this degree of automation or if you want a pure function, see the parseCommandLinePure function in the Multiarg.Internal module.

parseCommandLineHelp :: [OptSpec a] -> (String -> a) -> [String] -> ParsedCommandLine (Maybe a)

Automatically adds a short option, -h, and a long option, --help. Intended primarily for use by the parseCommandLineIO function.