[racket] An easy route to define-datatype in BSL?

On 2012-11-05 6:43 AM, Matthew Flatt wrote:

> Here's a first cut at a module that you can import into BSL programs.
>
> The least obvious part is defining a new `define-type' and `type-case'
> that invents hidden names for the variants and them maps between them
> while expanding to the original forms.

Wow, thanks. I will study the code and do my best to understand it, and 
test it for deployment next fall. I can already see the outline of how 
your code achieves what you describe, but could you please say a few 
words about why that's necessary, to improve my understanding of BSL? 
Thanks again. --PR