src/HOL/Tools/Function/context_tree.ML
2009-10-20 haftmann 2009-10-20 replaced old_style infixes eq_set, subset, union, inter and variants by generic versions
2009-07-17 wenzelm 2009-07-17 tuned/modernized Envir.subst_XXX;
2009-06-23 haftmann 2009-06-23 uniformly capitialized names for subdirectories