After I wrote CPU::Emulator::Z80, I needed an assembler so I could do anything with it. Rather than use any of the pre-existing ones, I thought it would be a good idea to write one in perl. So I did, and the ugly hack that was CPU::Z80::Assembler version 1 was the result. And boy is it ugly.
I wasn't really expecting anyone to use it other than myself, but Paulo Custodio did, and he found bugs, and he sent patches, with tests. He suggested some other improvements too, and I handed over maintenance to him. Version 2 gone done grown up, with a real lexer/parser, proper #include files and everything.
I'm very grateful.