#@deckyard/hl7

HL7 version 2 is how hospital systems tell each other about patients, orders, results and appointments: ADT (admissions), ORM / OML (orders), ORU (results), SIU (scheduling) and many more message types, each a list of pipe-delimited segments. This deck reads, changes and builds those messages in their usual encoding (ER7), acknowledges them, and moves them over MLLP, the TCP framing interfaces use.

• Messages and segments: parsing, paths, segment access, escapes, building messages, acknowledgements, character sets.
• MLLP: sending, receiving, serving.
• Cheatsheet: every export.

#Conventions

Snippets assume this import:

import "@deckyard/hl7/" as hl7;

Every failure is Error{kind: "hl7"} with a message that names what broke the rules. The deck is strict: input that breaks HL7's encoding is refused, never repaired. Segments end with CR (an LF is a control character and an error), delimiters come from MSH-1 and MSH-2 and nowhere else, an unknown escape sequence is an error. A parsed message keeps its text, so one that was not changed encodes back byte for byte.

try {
    def m as hl7.Message init hl7.parse($text);
} catch (e) {
    io.printf("%s\n", $e.message);
}

The deck does not validate a message against the structures of its HL7 version (which segments an ADT^A01 must have, the data types of each field): those tables are large and licence-restricted. It reads and writes any segment, including Z-segments.

The deck needs the net capability for MLLP and does not run on jennifer-tiny.