PyoLogo

PyoLogo

PyoLogo [pie-o-logo] or PYthon Open Logo is an implementation of the Logo programing language created on top of Python. It grew out of Arnan (Roger) Sipitakiat's thesis project at the MIT Media Laboratory. PyoLogo consists of a casual Logo interpreter and a simple IDE.

Current Status

Since PyoLogo is currently thesis software, it is far from being a complete product. Here is a list of things it can and cannot do.

Available features

• Logo Primitives. Supports a subset of Logo primitives. Download the command list
  • Most of the Turtle Geometry (drawing) primitives are available.
  • List and list manipulation commands
  • Common control flow. If, ifelse, repeat, etc
  • Variables. Using the 'make' command and some other alternatives
  • Mathematical operations. sin, cos, tan, sqrt, etc
• Supports multiple procedures with parameter passing and procedure output
• Multi-threaded. I.e. the 'launch' and 'forever' commands creates a new background process
• Support turtle shapes

Thesis Features

There are some non-traditional features built into PyoLogo for the thesis work form which it was created. Here are some that could perhaps be useful.

• Robotics. PyoLogo can receive sensor input and control actuators via the GoGo Board. Since OLPC will have a sensor input through its microphone jack, this feature can be adapted to make use of this possibility.
• Line objects. These are slider-like objects that can be used to track a turtle's position or visualize a sensor value.
• Variable history. Every variable keeps a record of its previous values. It can be used to calculate the rate of a variable (i.e. position -> speed) or for debugging purposes.

Issues and missing items

• Performance. PyoLogo currently runs very slowly on OLPC machines. This is based on the A test boards
• Still some UI issues under Linux
• Bugs are plentiful. Minimal error checking have been implemented into the Logo interpreter
• Error reporting. Errors in the Logo programs are not well reported. This makes it difficult for the user to debug their Logo program
• No multimedia support. No sound, no video, no text box
• No UI widgets. No buttons, checkboxes
• No multiple page support

Download

The author is currently preparing the source code to be uploaded into OLPC's code repository. Once this is done, a public release of the software will become available.

The Logo Interpreter

Casual Logo

Although PyoLogo tries to conform with other Logo implementations, it contains some rather unique unconventional properties.

• Not space delimited. 'Show 1+1' works in PyoLogo whereas most other Logo interpreters do not except this. Logo normally requires spaces between every token. So, only 'Show 1 + 1' would work. Although this breaks the uniformity of the Logo language, I believe this is a worthwhile trade off.
• Multiple ways to manipulate variables. I find Logo's 'make' primitive unnecessarily complicated for children. I prefer the 'set' method better. PyoLogo supports both. So,

make "counter 0
repeat 10 [ make "counter :counter + 1]
show :counter

The following alternative is also available

global [counter]

setcounter 0
repeat 10 [ setcounter counter + 1]
show counter