27 Sep 08:51 2012

## ANNOUNCE: Sylvia, a lambda calculus visualizer

```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.

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.

----------------

Source: https://github.com/lfairy/sylvia

Documentation: https://github.com/lfairy/sylvia/wiki

----------------
```
27 Sep 09:30 2012

### Re: ANNOUNCE: Sylvia, a lambda calculus visualizer

```On Wed, Sep 26, 2012 at 11:51 PM, 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.
>
> 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.
>
>
> ----------------
>
>
> Source: https://github.com/lfairy/sylvia
>
> Documentation: https://github.com/lfairy/sylvia/wiki
>
```

28 Sep 16:56 2012

### Re: ANNOUNCE: Sylvia, a lambda calculus visualizer

```
> Sylvia is a lambda calculus visualizer.

Such a thing is certainly nice to have.
I use this one for teaching:

http://joerg.endrullis.de/lambdaCalculator.html
```
2 Oct 04:23 2012

### Re: ANNOUNCE: Sylvia, a lambda calculus visualizer

```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
```

2 Oct 05:16 2012

### Re: ANNOUNCE: Sylvia, a lambda calculus visualizer

```On 2 October 2012 15:23, Conrad Parker <conrad <at> metadecks.org> wrote:
>
> 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).

Not sure if it's what you're after, but I was reminded of this (models
untyped lambda calculus):
http://worrydream.com/AlligatorEggs/

Alistair
```
2 Oct 07:04 2012

### Re: ANNOUNCE: Sylvia, a lambda calculus visualizer

```On Tue, Oct 2, 2012 at 3:23 PM, Conrad Parker <conrad <at> metadecks.org> wrote:
> 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.

Thanks for pointing that out! I've added an examples page at

<https://github.com/lfairy/sylvia/wiki/Examples>

>> 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.

Interesting! I'll have a closer look at it when I have the time.

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

That's exactly the point I'm trying to make :)

Heck, lambda calculus is just as simple as natural numbers (if not
simpler), yet people learn the former at university and the latter a
```