src/HOL/Datatype_Examples/Brackin.thy
2014-09-12 blanchet 2014-09-12 new datatype is too slow on the huge datatypes (at least the mutual ones) -- use 'old_datatype' instead
2014-09-11 blanchet 2014-09-11 renamed 'BNF_Examples' to 'Datatype_Examples' (cf. 'datatypes.pdf')