proper normal form for Perspective.ranges (overlapping ranges could be joined in wrong order, crashing multiple editor views); clarified Text.Range apartness, with try_restrict and try_join operations; private Perspective constructor to ensure abstract datatype integrity;
proper normal form for Perspective.ranges (overlapping ranges could be joined in wrong order, crashing multiple editor views);
clarified Text.Range apartness, with try_restrict and try_join operations;
private Perspective constructor to ensure abstract datatype integrity;

MerelyAPseudonym/isabelle,MerelyAPseudonym/isabelle,MerelyAPseudonym/isabelle,MerelyAPseudonym/isabelle,MerelyAPseudonym/isabelle,MerelyAPseudonym/isabelle