In real-world healthcare IT ecosystem HL7 v2 is a most widely used standard for data interoperability. New standards like HL7 v3 or FHIR are rather young to completely replace old and time-proven HL7 v2.
Blah-blah, we need to map from HL7 to FHIR.
So how can we describe mapping from HL7 v2 to FHIR? There are two options: imperative and declarative. Well-known products like MIRTH or