[racket-dev] Release Announcement for v6.1

On Mon, Jul 28, 2014 at 1:33 PM, Ryan Culpepper <ryanc at ccs.neu.edu> wrote:
> robby:
> - random generation from contracts (1cb1ff28, 76c6a1b7)
> - contract improvements (c64d70ab)
> - change semantics of _!_ variables under ellipses (69c96c62)
> - change metafunction contract formatting (d067311c)
> - recursive-contract and cyclic values
>   (7728e062, d664ee14, ..., 0db4df1d, f49dd363)
> - add dvipdf backend to scribble (5280395f)
> - add history (???) (3cd15cea, 145644ac, 83e8cfba, fb048647, d9dae651)

None of these seem particularly important to me. I guess the random
generation and the _!_ semantics changes are the most important of the
lot. Here are bullets for them, but feel free to leave them out:

- contracts: improved random generation for contracts; the contract
system can now easily find simple mistakes in data-structure
implementations (eg accidentally reversing a conditional in a heap
invariant check), given strong enough contracts

- redex: the semantics of mis-match patterns (variables followed by
_!_) inside ellipses has changed in a backwards incompatible way; they
semantics is now much clearer and now potentially even useful

Robby