This is what I miss most currently as bloody beginner (beside more precise parser and type checker error messages). Don't know if it is in the issue list so far but can't find it. e.g:

let (X a) = X b
in a

currently is not working, right? As far as I see the same applies to all other patterns.
I can write something like this instead, but it can make the code less clear (not in this example):

case X b of
  X a -> a