[Pl-seminar] Wadler's Blog: Oh no! Alligators!

Eli Barzilay eli at barzilay.org
Tue May 8 10:54:59 EDT 2007

Another toy in the same spirit is the `GCalc' game in PLT which I
wrote based on


But after I spent a good while with such toys it became clear that
these things are not much more than cute.  The reaction of many lambda
geeks is that they can use such things to explain the beauty of LC to
their 5yo kid and their grandmother.  It just doesn't work -- the
level of complexity is still the same, and real problems are on the
same interest level for both the geeks who like it and the rest of the
world.  If anything, using graphical symbols distract from the real
content -- I had several attempts that ended up in exactly the same
way as: "But she was most interested in drawing pictures of

(IMO, this alligator thing starts falling apart on the "Color Rule",
and ends up in the same mess that the GCalc thing is in: "I'd still
like to figure out how to make Church numerals (repeated application)
look less ugly"...)

On May  8, Mitchell Wand wrote:
> The Alligator game is great fun!  And Bret Victor sounds like a cool guy.
> http://wadler.blogspot.com/2007/05/oh-no-alligators.html
> Oh no! Alligators! <http://worrydream.com/AlligatorEggs> One of my great
> joys on visiting Berkeley was to meet Bret Victor, of Magic
> Ink<http://worrydream.com/MagicInk/>fame. I mentioned to him that I
> had been working with a student on a visual
> lambda calculus, in part because I wanted a way to explain lambda calculus
> to my eight-year old daughter and son. He responded with a
> game<http://worrydream.com/AlligatorEggs>involving alligators and
> their eggs, such a clever morphing of lambda
> calculus that it wasn't until I reached the end that I realized exactly what
> was going on.
> So far, I've had a chance to show it to my daughter, who managed to
> successfully solve the problem at the end. She guessed a definition of
> 'not', and then applied 'not' to 'true' and checked that the result is
> 'false'. But she was most interested in drawing pictures of alligators! I
> expect it would be more fun to use if there was software that implemented
> the game.
> Bret also pointed to David Keenan's graphical lambda
> calculus<http://users.bigpond.net.au/d.keenan/Lambda/>,
> based on Raymond Smullyan's "To Mock a Mockingbird".

          ((lambda (x) (x x)) (lambda (x) (x x)))          Eli Barzilay:
                  http://www.barzilay.org/                 Maze is Life!

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