Brandon Moore wrote in his answer to my PMC syntax proposal:

Maybe the '\' could be reiterated to introduce the layout group:

take' = \ 0 _ -> [] n \[] -> [] (x:x) -> x : take (pred n) xs

Definitely not, since the lambda gets us back into expressions, destroying the fall-through properties of matchings. (In this particular case this is no problem, but in general it would destroy fall-through.)

...

alt -> match exp with alts Maybe reuse "case", unless a new keyword is needed to avoid confusion.

We definitely need this construct to produce a matching (or ``alt''). If we use ``case'' here, then case expressions don't exist anymore. Wolfram