Hello all. I've been looking at the documentation on patterns and I have the following question. Say I have a Dataset with keys "a", "b" and "c". The "a" key is associated with an Integer, the "b" key is associated with a point which can be described by the pattern {Real,Real} and the "c" key is a String. I want to write a function F that takes such a Dataset as its only argument. I know that I could do the following:

A) F[arg_] Which would be the most general. More specifically, I can do:

B) F[arg_Dataset] which would accept any Dataset.

So, how can I specify that the argument a must a Dataset of the form described earlier.

Dataset[<| "a"->_Integer, "b"->{__Real,__Real} , "c"->_String |>]