pretty name for the CASE on a UNION value

In Algol68 pretty almost everything seems to yield a value (except loops, mode declarations and... ?) so it's easier (and probably more correct) to have "exprs" instead of "insts" (instructions) everywhere. The "resolvers" are probably wrong, but so far they work.

It doesn't really make sense to ask for both the initial and closing comment delimiter when they are always the same, just ask for one of o # o CO o COMMENT

Algol68 support three styles of comments: 1) COMMENT ... COMMENT 2) CO ... CO 3) # ... # These can't be nested, although you can have things like COMMENT CO ... CO COMMENT as a whole comment because from `COMMENT' up to the next closer `COMMENT' is a single comment (duh.)

that's not the way to do it

algol68g doesn't seem to support them