:: a typeCtrl KGHC 9.10.3 · lts/ghc-9.10.x · c74966e · 2026-09-27
Moduleturtle-1.6.2Haskell2010
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 ageSee the Turtle.Tutorial module which contains more examples on how to use command-line parsing.
A Parser a is an option parser returning a value of type a.
Functor ParserDefined in optparse-applicative-0.18.1.0 · Options.Applicative.TypesApplicative ParserDefined in optparse-applicative-0.18.1.0 · Options.Applicative.TypesAlternative ParserDefined in optparse-applicative-0.18.1.0 · Options.Applicative.TypesThe 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
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.
IsString CommandNameDefined in turtle-1.6.2 · Turtle.OptionsThe short one-character abbreviation for a flag (i.e. -n)
A brief description of what your program does
This description will appear in the header of the --help output
IsString DescriptionDefined in turtle-1.6.2 · Turtle.OptionsA helpful message explaining what a flag does
This will appear in the --help output
IsString HelpMessageDefined in turtle-1.6.2 · Turtle.OptionsParse a Text value as a flag-based option
Parse a Line value as a flag-based option
Parse an Int as a flag-based option
Parse an Integer as a flag-based option
Parse a Double as a flag-based option
Parse a FilePath value as a flag-based option
Parse any type that implements Read
Build a flag-based option parser for any type by providing a Text-parsing function
Parse a Text as a positional argument
Parse a Line as a positional argument
Parse an Int as a positional argument
Parse an Integer as a positional argument
Parse a Double as a positional argument
Parse a FilePath as a positional argument
Parse any type that implements Read as a positional argument
Build a positional argument parser for any type by providing a Text-parsing function
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
Create a named group of sub-commands
Parse the given options from the command line
Parse the given options from the command line and add additional information
Extended version of options with program version header and footer information