[int_19h]

Pattern matching shouldn't be hard to translate, really. It would not be a 1:1 mapping to the existing IEnumerable methods, but it's a straightforward translation to a single Select that returns a Nullable<ValueTuple> (to indicate match success/failure and pass the data in the former case) followed by a Where that would remove failures. Better yet, they could always add a new extension method to IEnumerable for this, and then translate to that.

One feature I'd like to see is integration with foreach so that you don't have to repeat the variable and come up with a different name to work around shadowing rules. I.e. instead of:

   foreach (var x in from x0 ...)

it would be nice to be able to write simply:

   foreach (from x in ...)

and have it "just work", including more complicated cases with multiple nested from-clauses, let etc (effectively extending the scope of all of those into the body of foreach).