🚀 go-pugleaf

One of the original questions was "Is SET OF CHAR a legal type?".

Some submissions discussed the contraints suggested or required for
the size N of "base type" T in "SET OF T".

I just want to point out that "SET OF CHAR" must be illegal because of
the other constraints put on T.  To narrow the report (already cited
by Frans van Otten) even more down:

pim3>	This must be a subrange type of the integers [...],
pim3>	or a (subrange of an) enumeration type ...

CHAR simply doesn't qualify.

There are several places in PIM3 where subranges and enumerations are
allowed and it was necessary to add CHAR and BOOLEAN explicitly, for
example consider index types of arrays.  Chapter 16 in the tutorial
section introduces BOOLEAN as a enumeration type.  This is conceptually
clear and consistent within in the entire language.  However, this
classification didn't make it into the reference part.  Don't ask me
why.  Likewise, Modula-2 could benefit from viewing CHAR as an
enumeration type in my opinion.

							Martin