[Haskell-cafe] ANNOUNCE: Sylvia, a lambda calculus visualizer

Conrad Parker conrad at metadecks.org
Tue Oct 2 04:23:50 CEST 2012

On 27 September 2012 14:51, Chris Wong <chrisyco+haskell-cafe at gmail.com> wrote:
> Hello all
> Some of you in the audience may have read Dave Keenan's paper, [To
> Dissect a Mockingbird][]. A subset of that may have wondered if it was
> possible to generate those pretty pictures programmatically. For that
> subset, I can answer to you -- yes, yes you can.
> [To Dissect a Mockingbird]: http://dkeenan.com/Lambda/
> Sylvia is a lambda calculus visualizer. It takes in an expression in
> the untyped lambda calculus and spits out a pretty picture.

Nice, it builds and runs fine for me. Perhaps you could include a few
more example commandlines to get started?  Running without arguments
(as the README.mkd suggests) just prints the help text.

> This is still in very early alpha, but it renders a fair number of
> combinators correctly. I plan to add animated reduction (once I figure
> out how to do it), and eventually develop this into a sandbox game of
> some sort. I'm hoping to get some comments and ideas on how I can take
> it from here.

I'd love to see a game which incrementally teaches reduction and
expansion steps in the way that DragonBox [http://dragonboxapp.com/]
teaches algebra. That would be a learning mode like Angry Birds, where
new combinator birds are introduced every few levels and a small
selection of useful birds are provided to help solve each level.

(Lambda calculus really should be a kids' game, grown-ups always make
it seem more complex than it is).


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