XPL
XPL is a programming language based on PL/I , a portable one-pass compiler written in its own language , and a parser generator tool for easily implementing similar compilers for other languages . 
<triplet> XPL <subj> programming language <obj> instance of <subj> PL/I <obj> based on <triplet> PL/I <subj> XPL <obj> derivative work <subj> programming language <obj> instance of