Logo 15-word challenge (1997)

These programs rely on Logo's turtle interface, which is a convenient and intuitive way to describe graphics imperatively. It's great for kids. These days, Python also has a turtle library (edit: built-in! part of the standard library, for some reason), heavily inspired by Logo, which means that the code on this page can be easily translated into Python. Here are some example that you can run at home (since I assume more people have access to Python these days than likely have a Logo interpreter installed). Edit: these are Python translations (by me) of the top three entries on the linked page.

    import turtle
    import math
    turtle.tracer(0,0) # remove this line to watch the drawing

    def spirals():
        # repeat 1800 [fd 10 rt repcount + .1]
        for repcount in range(1800):
             turtle.fd(10)
             turtle.rt(repcount+.1)
        turtle.update()

    def snowflakes(variant=6):
        # repeat 8 [rt 45 repeat 6 [repeat 90 [fd 2 rt 2] rt 90]]
        for _ in range(8):
            turtle.right(45)
            for _ in range(variant):
                for _ in range(90):
                    turtle.forward(2)
                    turtle.right(2)
                turtle.right(90)
        turtle.update()

    def orb():
        # for [i 0 420] [seth :i repeat :i [fd 2 rt 1] pu home pd]
        for i in range(0,420):
            turtle.seth(i)
            for _ in range(i):
                turtle.forward(2)
                turtle.right(1)
            turtle.penup()
            turtle.home()
            turtle.pendown()
        turtle.update()

Logo was my first programming experience - my older sister(who had Logo in school) introduced me to a few basic commands.

These quickly turned out to be insufficient, so I reverse-engineered the examples shipped with the platform. We didn't have internet access, so that was the only viable option.

When that turned out to be insufficient I noticed that many Logo commands were three characters long and highlighted, so I generated all the three-character combinations and checked them out one by one.

Turns out you can make games in Logo, but sounds and keyboard interactions introduce pauses in the main loop.

Eventually this new browser named Internet Explorer 6, which shipped with a language called JScript, proved to be more interesting, even though I didn't understand what a "<div>" was and how to write a for loop properly.

While this challenge does show off the complexity and beauty of Logo's "turtle graphics", it has often struck me as a tragedy of the language that, for most people who have encountered Logo, they are led to believe that graphics is all it can do (or its only purpose).

As a result of a recent thread[1] on HN regarding Logo, we now have a Slack workspace[2] and Freenode IRC channel[3] for Logo fans. Please do join them even if you don't remember Logo anymore. The intention here is not to discuss Logo but to share the joy of computing that we discovered through Logo and has remained in our lives.

[1]: https://news.ycombinator.com/item?id=21374341

[2]: https://bit.ly/fd100slackinvite

[3]: #fd100 at chat.freenode.net

Reminds me of Algorithmic Information Theory:

> Algorithmic information theory principally studies measures of irreducible information content of strings (or other data structures). Because most mathematical objects can be described in terms of strings, or as the limit of a sequence of strings, it can be used to study a wide variety of mathematical objects, including integers.

https://en.wikipedia.org/wiki/Algorithmic_information_theory

Cf. Chaitan, Kolmogorov, and Solomonoff.

Or Schmidhuber's "THEORY OF BEAUTY & LOW-COMPLEXITY ART" http://people.idsia.ch/~juergen/beauty.html

Even simple thing like drawing the Euler spiral has much more effect, if you visualize the turtle motion, so you can see how the motion turns at some point and the turtle starts going back on the same way down.

cs repeat 360 [fd 10 lt product 2 repcount wait 5]

or a variant of David Eisenstat's code:

cs pu setpos [-100 -100] pd repeat 8 [rt 45 repeat 4 [repeat 45 [fd 5 rt 2 wait 1] rt 135]]

of course Logo is LISP, so you can do stuff like

? show map [[x] se sum # x ?REST] [1 2 3]

[[2 2 3] [4 3] [6]]

Forth version: https://forthsalon.appspot.com/

Yehuda Katz's name is in there somewhere.

From one entry:

> The really interesting part is that the effect is entirely destroyed if you replace "fd 40 fd 40" by "fd 80".

Fascinating...

I wonder what would happen if you combined this with a Game of Life type algorithm?

How cute, each name links to their email address. Very 1997!