p package:optparse-applicative

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 Nothing) mempty

Group options together under a common heading in the help text. For example, if we have:

Args
<$> parseMain
<*> parserOptionGroup "Group A" parseA
<*> parserOptionGroup "Group B" parseB
<*> parseOther

Then the help page will look like:

Available options:
<main options>
<other options>

Group A
<A options>

Group B
<B options>

backtrack to parent parser when a subcommand fails (default: Backtrack)

Width at which to hang the brief description

number of columns in the terminal, used to format the help page (default: 80)

automatically disambiguate abbreviations (default: False)

when displaying long names in usage and help, use an '=' sign for long names, rather than a single space (default: False)

when displaying subparsers' usage help, show parent options under a "global options" section (default: False)

metavar suffix for multiple options

show the help text for a command or subcommand if it fails with no input (default: False)

always show help text on parse errors (default: False)

Indentation width for tables

Create a ParserPrefs given a modifier

Specify a short program description.

Specify a short program description as a 'Prettyprinter.Doc AnsiStyle' value.

Convert a paragraph into a Chunk. The resulting chunk is composed by the words of the original paragraph separated by softlines, so it will be automatically word-wrapped when rendering the underlying document. This satisfies:

isEmpty . paragraph = null . words

Generate the help text for a program.

Generate option summary.

Layout a document depending on the page width, if one has been specified.

>>> let prettyPageWidth (AvailablePerLine l r) = "Width:" <+> pretty l <> ", ribbon fraction:" <+> pretty r

>>> let doc = "prefix" <+> pageWidth (brackets . prettyPageWidth)

>>> putDocW 32 (vsep [indent n doc | n <- [0,4,8]])
prefix [Width: 32, ribbon fraction: 1.0]
prefix [Width: 32, ribbon fraction: 1.0]
prefix [Width: 32, ribbon fraction: 1.0]

>>> parens "·"
(·)

>>> pipe
|

(plural n one many) is one if n is 1, and many otherwise. A typical use case is adding a plural "s".

>>> let things = [True]

>>> let amount = length things

>>> pretty things <+> "has" <+> pretty amount <+> plural "entry" "entries" amount
[True] has 1 entry

>>> pretty 1 <+> pretty "hello" <+> pretty 1.234
1 hello 1.234