Tony Morris

@dibblego pedantically only != on Ints. “Immortality” is in List.indexOf. And essentially in Scala spec (equals:Any=>Boolean defined on Any)

@wbillingsley You rely on bottom values to make the case. This is immoral in the fast and loose reasoning sense. There is no "pedantically."

@dibblego if by “fast and loose” you mean http://dl.acm.org/citation.cfm?doid=1111037.1111056 … "morally correct" seems to refer to reasoning not program. ?

@wbillingsley reasoning about programs.

@dibblego Yes. So not “that fn uses == so is immoral” but “f+l reasoning claim is not 'morally correct' for Scala because Scala has Any” ?

@wbillingsley Scala has nothing to do with it. The equals functions violates parametricity and porticoes the escape hatch for lies.

@dibblego @wbillingsley It is perfectly possible to formulate a theory of parametricity on types with additional structure like 'equals'.

@dibblego @wbillingsley E.g., Simpson and Møgelberg do so for types that have algebraic structure: http://lmcs-online.org/ojs/viewarticle.php?id=449&layout=abstract …