module { export = [main], features = [chr] } import "StandardLibrary" data V = V { x :: Double, y :: Double } main = () where constraint X V X V { ?x } => print ?x X V { ?y } => print ?y True => X V { x = 1.0, y = 2.0 } True => X V { x = 3.0, y = 4.0 } -- 1.0 2.0 3.0 4.0 () -- module { export = [main], features = [chr] } import "StandardLibrary" data V = V { x :: Double, y :: Double } main = () where constraint X V True => X V { x = 1.0 } -- 9:15-9:28: Field y not defined.