Bent Bruun Kristensen Ole Lehrmann Madsen Birger Møller-Pedersen The when, why and why not of the BETA programming language. 1-57 2007 conf/hopl/2007 HOPL http://doi.acm.org/10.1145/1238844.1238854 db/conf/hopl/hopl2007.html#KristensenMM07