This is simple-graphics, a turtle graphics library for Chicken Scheme.

It is designed for educational use, to let new programmers quickly
have something interesting they can program the computer to do: draw
pictures. This has more immediate appeal than arithmetic...

There are dedicated turtle graphics apps out there, and there's the
original Logo programming language that really pioneered the use of
turtle graphics in education, but my simple graphics engine is
slightly special: you use it through a normal Scheme interactive
prompt rather than a special "dumbed down" interpreter. That means you
can start by typing in simple graphics commands that are executed
immediately, then slowly progress to use the full power of Lisp - a
language capable of "lowly" systems programming, commercial
applications, or advanced artificial intelligence and computer science
research.

Having that continuum is valuable in subtle ways. A learner can start
by drawing simple pictures then, with a little assistance, connect to
a Web server to obtain live temperature readings from sensors and draw
a dashboard with moving gauges and charts of previous values. They can
migrate towards solving "real problems" and producing useful software
in a series of tractable steps. They can develop the confidence to
leave the simple interactive turtle graphics environment and produce
other kinds of software, such as command-line tools, network daemons,
and Web applications, without needing to overcome any fundamental
hurdles.

Please see [https://wiki.call-cc.org/eggref/4/simple-graphics|the egg page in the Chicken Wiki for the documentation].