BUGS (Bayesian inference Using Gibbs Sampling) is a software for the Bayesian analysis of statistical models using Markov chain Monte Carlo (MCMC) methods. It allows to describe graphical models using a declarative langauge.
FOPPL (First Order Probabilistic Programming Language) is a stripped down version of Anglican, a probabilistic programming language based on Clojure.
The ANLTRv4 specification of BUGS grammar was obtained heavily inspired with the FLEX+BISON lexing and parsing grammar incorporated in JAGS 4.3.0 source code, in files src/lib/compiler/parser.yy and src/lib/compiler/scanner.ll.
I use my 'custom' version of clj-antlr.