I wrote a really simple ruby gem to parse HL7 into ruby. It's super easy to extend, all you have to do is define a new class containing a function-to-column map. The key is the name of the function to call against a HL7 segment and the value is the position of the element in HL7 segment that you want the function to return. Check it out here: https://github.com/sufyanadam/simple_hl7_parser