P.S. Actually - despite arguing - I do not totally oppose having a separate unary transformation functions map-someting defined for a sequence (returning an empty sequence for an empty input) Just they will add absolutely no functionality compared with the one currently suggested, while it is several extra functions.. P.P.S. whatever - I will send out a new table, including map-somethings in about 30 min - we can discuss it later. P.P.P.S. Please, add the AttributeValue support for specifying sequences to the issues list. (or using Attribute, from the context schema as input to functions..)