Twenty years after

I just shipped what was probably the silliest and most pointless software release of my career. But hey, it’s the reference implementation of a language and I’m funny that way.

Because I write compilers for fun, I have a standing offer out to reimplement any weird old language for which I am sent a sufficiently detailed softcopy spec. (I had to specify softcopy because scanning and typo-correcting hardcopy is too much work.)

In the quarter-century this offer has been active, I have (re) implemented at least the following: INTERCAL, Michigan Algorithmic Decoder, and a pair of obscure 1960s teaching languages called CORC and CUPL, and an obscure computer-aided-instruction language called Pilot.

Pilot…that one was special. Not in a good way, alas. I don’t know where I bumped into a friend of the language’s implementor, but it was in 1991 when he had just succeeded in getting IEEE to issue a standard for it – IEEE Std 1154-1991. He gave me a copy of the standard.

I should have been clued in by the fact that he also gave me an errata sheet not much shorter than the standard. But the full horror did not come home to me until I sat down and had a good at both documents – and, friends, PILOT’s design was exceeded in awfulness only by the sloppiness and vagueness of its standard. Even after the corrections.

But I had promised to do a reference implementation, and I did. Delivered it to the inventor’s friend. He couldn’t get it to work – some problem with the version of YACC he was using, if I recall correctly. It wasn’t something I could fix remotely, and I left it to him to figure out, being pretty disgusted with the project. I don’t know if he ever did.

I did fix a couple of minor bugs in my masters; I even shipped occasional releases until late 1996. Then…I let the code molder in a corner for twenty years.

But these things have a way of coming back on you. I got a set of fixes recently from one Frank J. Lhota, forward-porting it to use modern Bison and Flex versions. Dear sweet fornicating Goddess, that meant I’d have to…issue another release. Because it’s bad form to let fix patches drop on the floor pour discourager les autres.

So here it is. It does have one point of mild interest; the implementation is both an interpreter and a compiler (it’s a floor wax! It’s a dessert topping!) for the language – that is, it can either interpret the parsed syntax tree or generate and compile corresponding C code.

I devoutly hope I never again implement a language design as botched as Pilot. INTERCAL was supposed to be a joke…