Warning when attempting to patternmatch on unimported constructors

[sxhya]

In this code sample true and false should be highlighted as variables, whose names clash with the names of the (unimported) constructors of the datatype Bool.

\import Data.Bool(Bool, if)

\func bar (b : Bool) : Nat => \case b \with {
  | true => 1
  | false => 0
}