import "Prelude"

data XYZ = XYZ { x :: Double, y :: Double, z :: Double }
deriving instance Show XYZ

updateX x' XYZ {..} = XYZ {x', ..} 

main = print $ updateX 5 $ XYZ { x = 4, y = 3, .. }
  where
    z = 2
-- 
XYZ 5.0 3.0 2.0
()
--
import "Prelude"

main = ()
  where
    constraint R { a :: Integer, b :: Integer, label :: String }
    
    -R { a = 0, ..   } => print "Final: b = \(?b), label = \(?label)"
    -R { ?a,  ?b, .. } => R { a=?a-1, b=?b+1, .. }
    
    True => R { a = 5, b = 5, label = "My label" } 
--
Final: b = 10, label = My label
()