+-------+---+   +-------+-------+-------+
|       |   |   |       |       |       |
|  +-+  |   +---+  +-+  |  +----+  +-+  |
|  | +--+       |  | |  |  |    |  | |  |
|  +-+  |   |   |  +-+  |  +--  |  +-+  |
|       |   |   |       |       |       |
+-------+---+   +-------+-------+-------+
            +---+ 


Chicken + Logo = Chogo!

Chogo is a Logo interpreter written in Chicken Scheme.


.[!].  CURRENT STATUS

Very much a work in progress, but usable (if you know what you're doing ;-).


.[!].   REQUIREMENTS

- Chicken Scheme, obviously. ;-) Current version used for development
  is 4.11.0. Other versions may or may not work.
  See: [http://www.call-cc.org/]

- Eggs:
  - miscmacros
  - args
  - tk (if you want turtle graphics) (which you do)

- rlwrap (optional, but useful if you want a readline-enabled REPL)
  See: [http://utopia.knoware.nl/~hlub/rlwrap/]
  (or on OS X with Homebrew, "brew install rlwrap")

.[!].   RATIONALE

I am writing Chogo for personal use; to learn more about language
implementation, and to have a Logo interpreter that I can use with the
book _Turtle_Geometry_. (Note that Chogo's syntax is *not* the same as
the pseudocode used in the book, though. Much like all other Logo
implementations, it has its own unique syntax. I will write more about
this when/if the project matures a bit. There won't be *that* much of a
difference, though.)

(See: Turtle Geometry: The Computer as a Medium for Exploring
Mathematics, by Abelson & diSessa. [ http://www.amazon.com/dp/0262510375 ])


.[!].   QUICK START

Assuming you have rlwrap installed, and you are on an Unixoid system,
you can run the included 'chogo' script (which is really a one-liner at
the moment, but should become more sophisticated in the future :-).

Otherwise, just run chogo.scm with csi:

  $ csi -ss chogo.scm

Load and execute a file:

  $ ./chogo <filename>

or
 
  $ csi -ss chogo.scm <filename>

Create a new canvas for turtle drawing using the REPL, and start drawing:

  > canvas 500 500
  > forward 90

(Currently the turtle itself is not displayed... like I said, it's
very much a work in progress.)