Module System.Console.GetOpt

This module is a modified version of the module System.Console.GetOpt by Sven Panne from the ghc-base package. It has been adapted for Curry by Bjoern Peemoeller

(c) Sven Panne 2002-2005 The Glasgow Haskell Compiler License

Copyright 2004, The University Court of the University of Glasgow. All rights reserved.

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Exported Datatypes: ArgDescr, ArgOrder, OptDescr

Exported Functions: getOpt, getOpt', usageInfo

Exported Datatypes

data ArgOrder a

To hopefully illuminate the role of the different data structures, here are the command-line options for a (very simple) compiler, done in two different ways. The difference arises because the type of getOpt is parameterized by the type of values derived from flags. A type to describe what to do with options following non-options.

Constructors:

  • RequireOrder :: ArgOrder a no option processing after first non-option
  • Permute :: ArgOrder a freely intersperse options and non-options
  • ReturnInOrder :: (String -> a) -> ArgOrder a wrap non-options into options
data OptDescr a

Each OptDescr describes a single option.

The arguments to Option are:

  • list of short option characters
  • list of long option strings (without --)
  • argument descriptor
  • explanation of option for user

Constructors:

data ArgDescr a

Describes whether an option takes an argument or not, and if so how the argument is injected into a value of type @a@.

Constructors:

  • NoArg :: a -> ArgDescr ano argument expected
  • ReqArg :: (String -> a) -> String -> ArgDescr aoption requires argument
  • OptArg :: (Maybe String -> a) -> String -> ArgDescr aoptional argument

Exported Functions

usageInfo :: String -> [OptDescr a] -> String  Deterministic 

Return a string describing the usage of a command, derived from the header (first argument) and the options described by the second argument.

:: String 
-> [OptDescr a]  header
-> String  option descriptors

getOpt :: ArgOrder a -> [OptDescr a] -> [String] -> ([a], [String], [String])  Deterministic 

Process the command-line and return the list of values that matched (and those that did not match). The arguments are:

  • The order requirements (see ArgOrder)
  • The option descriptions (see OptDescr)
  • The actual command line arguments (presumably got from System.Environment.getArgs).

getOpt returns a triple consisting of the option arguments, a list of non-options, and a list of error messages.

:: ArgOrder a 
-> [OptDescr a]  non-option handling
-> [String]  option descriptors
-> ([a], [String], [String])  the command-line arguments

getOpt' :: ArgOrder a -> [OptDescr a] -> [String] -> ([a], [String], [String], [String])  Deterministic 

This is almost the same as getOpt but returns a quadruple consisting of the option arguments, a list of non-options, a list of unrecognized options, and a list of error messages.

:: ArgOrder a 
-> [OptDescr a]  non-option handling
-> [String]  option descriptors
-> ([a], [String], [String], [String])  the command-line arguments