secret

A Secret a newtype whose Show renders a redacted placeholder and whose ToJSON/FromJSON, ToCBOR/FromCBOR and Serialise instances are compile-time errors carrying a custom message (via TypeError). The instances stay visible to the constraint solver, so a record containing a Secret field can still deriving stock (Show) for free while any attempt to serialise it fails to compile. The only accessor is the continuation-style withSecret; there is no revealSecret.