[quiz] Quiz #2 - Argh! The parenthesis! They burn my eyes!

[Marco Baringer]

Argh! The parenthesis! They burn my eyes!
-----------------------------------------

Overview
========

One of the more common complaints people have against the lisp
language family is the abbundance of parenthesis is source code. "To
hell with 'em!" I hear you say, and you're right, but it still makes
for an interesting quiz.

Goal
====

You're going to prove that common lisp really is the "Programmable
Programming Language"[1] by changing the syntax to use less
parenthesis.

Write a function quiz2::read-off-side which allows python-style
whitspace-sensitive source code (this is sometimes called the "off
side" rule[2]). This function will be bound to the #!  dispatching
macro character and so must have this api (the test suite assumes
this):

(quiz2::read-off-side stream subchar parameter) => form

The easiest way to explain how the syntax works is to show it.

Example 1:

#!                                      
when
  t
  (do-stuff)
!# 
=> (progn (when t (do-stuff)))

Example 2:

1:#!
2:cond
3:  (zerop a)
4:    (write-line "A is zero.")
5:  (plusp a)
6:    (write-line "A is positive.")
7:  t
8:    (write-line "A is negative.")
9:(write-line "Done.")
b:!#
=>
(progn
  (cond
    ((zerop a)
     (write-line "A is zero."))
    ((plusp a)
     (write-line "A is positive."))
    (t
     (write-line "A is negative.")))
  (write-line "Done."))

If you doubts on how a form should be parsed see the print-off-sides
function in the test suite.

Test Suite
==========

A test suite is available at:

http://common-lisp.net/project/quiz/quizzes/quiz2/test.lisp

You'll need to load your code before that file, it assumes the quiz2
package, and read-off-side function, already exist. After you've
loaded the file execute (5am:run! :quiz2) to run the test suite, it
uses my FiveAM[3] test suite. If you want to rewrite the test suite
using another framework go ahead, I'll add a link to your rewrite
here.

[1] - John Foderaro, CACM, September 1991
[2] - http://en.wikipedia.org/wiki/Off-side_rule
[3] - http://common-lisp.net/project/bese/FiveAM.html


-- 
-Marco
Ring the bells that still can ring.
Forget the perfect offering.
There is a crack in everything.
That's how the light gets in.
	-Leonard Cohen