command-line
============
Command line argument handling for R7RS Scheme.

Description
-----------
This Scheme library provides a way to collect command line arguments
into an association list according to a simple S-expressive options
grammar. It's meant to be easy to use and pure-R7RS.

Usage
-----
One procedure is provided, `parse-command-line`, which takes as
arguments an options grammar and an optional list of string command line
arguments and returns an association list. If no list of arguments is
given, the program's command line arguments are used.

    (import (foldling command-line))
    
    (parse-command-line
     '("-a" "-b" "one" "-c" "two" "three" "-d" "four" "5" "six")
     `((-a)
       (-b . foo)
       (-c bar baz)
       (-d ,string->symbol ,string->number)))
    
    ; => ((-a)
    ;     (-b . "one")
    ;     (-c "two" "three")
    ;     (-d four 5)
    ;     (-- "six"))

As a special case, an item in the grammar whose first element is a list
will be split into separate entries, allowing an abbreviated syntax for
multiple option specifications of the same form:

    (parse-command-line
     '(((--foo --bar --baz) . qux)))
    
    ; => (parse-command-line
    ;     '((--foo . qux)
    ;       (--bar . qux)
    ;       (--baz . qux)))

Handlers for `getopt(3)` and `getopt_long(3)`-style command lines are
provided by the `getopt` and `getopt-long` sublibraries, respectively.
These can be provided as the first argument to `parse-command-line`, to
customize its option-matching behavior.

    (import (foldling command-line)
            (foldling command-line getopt)
            (foldling command-line getopt-long))
    
    (parse-command-line               ; => ((-a)
     getopt                           ;     (-b)
     '("-abcone" "-d" "two")          ;     (-c . "one")
     '((-a)                           ;     (-d . "two")
       (-b)                           ;     (--))
       (-c . one)
       (-d . two)))
    
    (parse-command-line               ; => ((-a . "one")
     getopt-long                      ;     (--foo)
     '("-aone" "--foo" "--bar=two")   ;     (--bar . "two")
     '((-a . one)                     ;     (--))
       (--foo)
       (--bar . two)))

Refer to `command-line.scm` for more API details.

Installation
------------
To install for CHICKEN Scheme, run `chicken-install` from the project's
root directory.

    $ git clone git://bitbucket.org/evhan/command-line.git
    $ cd command-line
    $ chicken-install -test

Other Schemes should install the following files:

    src/foldling/command-line.scm
    src/foldling/command-line.sld
    src/foldling/command-line/getopt.scm
    src/foldling/command-line/getopt.sld
    src/foldling/command-line/getopt-long.scm
    src/foldling/command-line/getopt-long.sld

Author
------
Evan Hanson <evhan@foldling.org>

License
-------
This software is written by Evan Hanson and placed in the Public
Domain. All warranties are disclaimed.