harr (12/10/82)
In response to (unc.4394) from unc!tas here is an esoteric and interesting
point for Prolog NU7 users. Prolog allows terms to be enclosed by single
quotes (') to allow the inclusion of any ascii code in a term name.
It so happens that '' (a null term) is defined, accepted, and processed
by the interpreter. Now the single quote is only used for purposes
of reading in a term from the user. Therefore the predicate "display"
will only write what is inbetween the quotes - which happens to be nothing.
In fact if one writes as a term:
''('').
then the interpreter writes the following:
?- display('').
().
yes
?-
Anyone have a novel semantic meaning or use for terms with this type
of name (as the name of a predicate - it is a useful 'null' term)?
- REH -
decvax!crwuecmp!harr