Parse docopt-formatted usage patterns.

For help with the docopt usage format, see the readme on github.

Same as parseUsage, but exitWithUsage on parse failure. E.g.

let usageStr = "Usage:\n  prog [--option]\n"
patterns <- parseUsageOrExit usageStr

Parse command line arguments.

Same as parseArgs, but exitWithUsage on parse failure. E.g.

args <- parseArgsOrExit patterns =<< getArgs

The abstract data type ParseError represents parse errors. It provides the source position (SourcePos) of the error and a list of error messages (Message). A ParseError can be returned by the function parse. ParseError is an instance of the Show and Eq classes.

An abstract data type which represents Docopt usage patterns.

Retrieve the original usage string.

Exit after printing usage text.

Exit after printing a custom message followed by usage text. Intended for convenience when more context can be given about what went wrong.

A named leaf node of the usage pattern tree

Maps each Option to all of the valued parsed from the command line (in order of last to first, if multiple values encountered)

True if an option was present at all in an invocation.

Useful with longOptions and shortOptions, and in conjunction with when.

Just the value of the argument supplied, or Nothing if one was not given.

If the option's presence is required by your Docopt usage text (e.g. a positional argument), as in

Usage:
  prog <required>

then getArg args (argument "required") is guaranteed to be a Just.

Same as getArg, but exitWithUsage if Nothing.

As in getArg, if your usage pattern required the option, getArgOrExitWith will not exit.

Same as getArg, but eliminate Nothing with a default argument.

Returns all occurrences of a repeatable option, e.g. <file>....

Return the number of occurrences of an option in an invocation.

Useful with repeatable flags, e.g. [ -v | -vv | -vvv].

For Usage: prog cmd, ask for command "cmd".

For Usage: prog - or Usage: prog [-], ask for command "-". Same for --.

For Usage: prog <file>, ask for argument "file".

Note: A Usage: prog --output=<file> is not matched by argument "file". See longOption.

For Usage: prog -h, ask for shortOption 'h'.

For Usage: prog -o=<file>, ask for shortOption 'o'.

For Usage: prog --version, ask for longOption "version".

For Usage: prog --output=<file>, ask for longOption "output".