argparser

Command line parsing framework for console applications

Monthly Downloads: 8

Programming language: Haskell

License: BSD 3-clause "New" or "Revised" License

Tags: Console    

README

ArgParser

Declarative & minimalist command line app framework for haskell

This framework is inspired by the argparse package found in python batteries.

This library provides a small combinator dsl to specify a parser for a datatype. Running the parser will automatically consume and convert command line arguments. Default special action such as help/usage are automatically built from the parser specification.

Here is a quick example. First, we need a datatype:

data MyTest = MyTest Int Int
  deriving (Show) -- we will print the values

Then, we define a parser:

myTestParser :: ParserSpec MyTest
myTestParser = MyTest
  `parsedBy` reqPos "pos1"
  `andBy` optPos 0 "pos2"

we can now run a MyTest -> IO () value. It will either perform the action with the parse result, or display an error message:

main = withParseResult myTestParser print

Building this app will produce an executable foo which will behave like this:

$ foo 1 2
MyTest 1 2
$ foo 3
MyTest 3 0
$ foo -h
foo
usage : foo pos1 [pos2] [-h] [--version]

mandatory arguments:
 pos1

optional arguments:
 pos2
 -h, --help                    show this help message and exit
 --version                     print the program version and exit

For more information, please visit http://hackage.haskell.org/package/argparser-0.3.2/docs/System-Console-ArgParser.html .