"Kendall grabbed a copy of everything he could, returned to the Oracle office, and began reading. One of the books he picked-up was a publication titled, “DIANA

"Kendall grabbed a copy of everything he could, returned to the Oracle office, and began reading. One of the books he picked-up was a publication titled, “DIANA: An Intermediate Language for Ada,” by Gerhard Goos, William A. Wulf, Arthur Evans Jr., and Kenneth J. Butler. This publication, written as a reference manual, contained not only the Ada language grammar but also the Interface Definition Language (IDL) specification of the Descriptive Intermediate Attributed Notation for Ada – the predominant Ada intermediate representation of the time. With this information at hand, in January of 1987, the first line of PL/SQL compiler code was written. The PL/SQL compiler began as a verbatim copy of the specification. Kendall wrote the original YACC-based parser using the manual’s Ada grammar and generated a DIANA tree directly from the syntactic rule actions. Unlike compilers for other languages, which often generate an abstract syntax tree and then translate that tree to the intermediate language, this direct approach worked well for an Ada-like language – particularly as the reference manual represented the IDL and grammar in an interlaced fashion."