Safe Haskell	None
Language	Haskell2010

Turtle.Options

Contents

Types
Flag-based option parsers
Positional argument parsers
Consume parsers

Description

Example usage of this module:

-- options.hs

{-# LANGUAGE OverloadedStrings #-}

import Turtle

parser :: Parser (Text, Int)
parser = (,) <$> optText "name" 'n' "Your first name"
             <*> optInt  "age"  'a' "Your current age"

main = do
    (name, age) <- options "Greeting script" parser
    echo (repr (format ("Hello there, "%s) name))
    echo (repr (format ("You are "%d%" years old") age))

$ ./options --name John --age 42
Hello there, John
You are 42 years old

$ ./options --help
Greeting script

Usage: options (-n|--name NAME) (-a|--age AGE)

Available options:
 -h,--help                Show this help text
 --name NAME              Your first name
 --age AGE                Your current age

See the Turtle.Tutorial module which contains more examples on how to use command-line parsing.

Synopsis

data Parser a
newtype ArgName = ArgName {
- getArgName :: Text
}
newtype CommandName = CommandName {
- getCommandName :: Text
}
type ShortName = Char
newtype Description = Description {
- getDescription :: Doc
}
newtype HelpMessage = HelpMessage {
- getHelpMessage :: Text
}
switch :: ArgName -> ShortName -> Optional HelpMessage -> Parser Bool
optText :: ArgName -> ShortName -> Optional HelpMessage -> Parser Text
optLine :: ArgName -> ShortName -> Optional HelpMessage -> Parser Line
optInt :: ArgName -> ShortName -> Optional HelpMessage -> Parser Int
optInteger :: ArgName -> ShortName -> Optional HelpMessage -> Parser Integer
optDouble :: ArgName -> ShortName -> Optional HelpMessage -> Parser Double
optPath :: ArgName -> ShortName -> Optional HelpMessage -> Parser FilePath
optRead :: Read a => ArgName -> ShortName -> Optional HelpMessage -> Parser a
opt :: (Text -> Maybe a) -> ArgName -> ShortName -> Optional HelpMessage -> Parser a
argText :: ArgName -> Optional HelpMessage -> Parser Text
argLine :: ArgName -> Optional HelpMessage -> Parser Line
argInt :: ArgName -> Optional HelpMessage -> Parser Int
argInteger :: ArgName -> Optional HelpMessage -> Parser Integer
argDouble :: ArgName -> Optional HelpMessage -> Parser Double
argPath :: ArgName -> Optional HelpMessage -> Parser FilePath
argRead :: Read a => ArgName -> Optional HelpMessage -> Parser a
arg :: (Text -> Maybe a) -> ArgName -> Optional HelpMessage -> Parser a
subcommand :: CommandName -> Description -> Parser a -> Parser a
subcommandGroup :: forall a. Description -> [(CommandName, Description, Parser a)] -> Parser a
options :: MonadIO io => Description -> Parser a -> io a

Types

data Parser a #

A Parser a is an option parser returning a value of type a.

Instances

Functor Parser
Instance details Defined in Options.Applicative.Types Methods fmap :: (a -> b) -> Parser a -> Parser b # (<$) :: a -> Parser b -> Parser a #
Applicative Parser
Instance details Defined in Options.Applicative.Types Methods pure :: a -> Parser a # (<>) :: Parser (a -> b) -> Parser a -> Parser b # liftA2 :: (a -> b -> c) -> Parser a -> Parser b -> Parser c # (>) :: Parser a -> Parser b -> Parser b # (<*) :: Parser a -> Parser b -> Parser a #
Alternative Parser
Instance details Defined in Options.Applicative.Types Methods empty :: Parser a # (<\|>) :: Parser a -> Parser a -> Parser a # some :: Parser a -> Parser [a] # many :: Parser a -> Parser [a] #

newtype ArgName Source #

The name of a command-line argument

This is used to infer the long name and metavariable for the command line flag. For example, an ArgName of "name" will create a --name flag with a NAME metavariable

Constructors

ArgName
Fields getArgName :: Text

Instances

IsString ArgName Source #
Instance details Defined in Turtle.Options Methods fromString :: String -> ArgName #

newtype CommandName Source #

The name of a sub-command

This is lower-cased to create a sub-command. For example, a CommandName of "Name" will parse name on the command line before parsing the remaining arguments using the command's subparser.

Constructors

CommandName
Fields getCommandName :: Text

Instances

IsString CommandName Source #
Instance details Defined in Turtle.Options Methods fromString :: String -> CommandName #

type ShortName = Char Source #

The short one-character abbreviation for a flag (i.e. -n)

newtype Description Source #

A brief description of what your program does

This description will appear in the header of the --help output

Constructors

Description
Fields getDescription :: Doc

Instances

IsString Description Source #
Instance details Defined in Turtle.Options Methods fromString :: String -> Description #

newtype HelpMessage Source #

A helpful message explaining what a flag does

This will appear in the --help output

Constructors

HelpMessage
Fields getHelpMessage :: Text

Instances

IsString HelpMessage Source #
Instance details Defined in Turtle.Options Methods fromString :: String -> HelpMessage #

Flag-based option parsers

switch :: ArgName -> ShortName -> Optional HelpMessage -> Parser Bool Source #

This parser returns True if the given flag is set and False if the flag is absent

optText :: ArgName -> ShortName -> Optional HelpMessage -> Parser Text Source #

Parse a Text value as a flag-based option

optLine :: ArgName -> ShortName -> Optional HelpMessage -> Parser Line Source #

Parse a Line value as a flag-based option

optInt :: ArgName -> ShortName -> Optional HelpMessage -> Parser Int Source #

Parse an Int as a flag-based option

optInteger :: ArgName -> ShortName -> Optional HelpMessage -> Parser Integer Source #

Parse an Integer as a flag-based option

optDouble :: ArgName -> ShortName -> Optional HelpMessage -> Parser Double Source #

Parse a Double as a flag-based option

optPath :: ArgName -> ShortName -> Optional HelpMessage -> Parser FilePath Source #

Parse a FilePath value as a flag-based option

optRead :: Read a => ArgName -> ShortName -> Optional HelpMessage -> Parser a Source #

Parse any type that implements Read

opt :: (Text -> Maybe a) -> ArgName -> ShortName -> Optional HelpMessage -> Parser a Source #

Build a flag-based option parser for any type by providing a Text-parsing function

Positional argument parsers

argText :: ArgName -> Optional HelpMessage -> Parser Text Source #

Parse a Text as a positional argument

argLine :: ArgName -> Optional HelpMessage -> Parser Line Source #

Parse a Line as a positional argument

argInt :: ArgName -> Optional HelpMessage -> Parser Int Source #

Parse an Int as a positional argument

argInteger :: ArgName -> Optional HelpMessage -> Parser Integer Source #

Parse an Integer as a positional argument

argDouble :: ArgName -> Optional HelpMessage -> Parser Double Source #

Parse a Double as a positional argument

argPath :: ArgName -> Optional HelpMessage -> Parser FilePath Source #

Parse a FilePath as a positional argument

argRead :: Read a => ArgName -> Optional HelpMessage -> Parser a Source #

Parse any type that implements Read as a positional argument

arg :: (Text -> Maybe a) -> ArgName -> Optional HelpMessage -> Parser a Source #

Build a positional argument parser for any type by providing a Text-parsing function

Consume parsers

subcommand :: CommandName -> Description -> Parser a -> Parser a Source #

Create a sub-command that parses CommandName and then parses the rest of the command-line arguments

The sub-command will have its own Description and help text

subcommandGroup :: forall a. Description -> [(CommandName, Description, Parser a)] -> Parser a Source #

Create a named group of sub-commands

options :: MonadIO io => Description -> Parser a -> io a Source #

Parse the given options from the command line