[long]

Both. (source: I've worked on both languages and versions of the book).

But give webppl a shot -- it's a good language!

[shanusmagnus]

Curious -- do you have any insider perspective on the reason for the changeover from Church?

[long]

A non-exhaustive list:

1. Pedagogically, the lispy syntax was a big stumbling block for beginners. Probabilistic programming is hard enough as it is; prefix notation and parens only added difficulties (and these difficulties were unrelated to the conceptual material).

2. webchurch compiled to Javascript anyway, so it was nice to be closer to the target language.

3. Lisp can be a bit awkward for certain contemporary programming idioms (e.g., accessing object properties).

[TeMPOraL]

I will. I don't doubt it's good. It's the Smug Lisp Weenie in me that's sad.