🚀 go-pugleaf

I've been asked to help someone with a Turbo Prolog program.
I believe it used to work under 1.3 (there's an object version running),
but the 2.0 compiler doesn't like it at all.  I have hunted through
the Turbo Prolog 2.0 Reference Guide and the Turbo Prolog 2.0 User's Guide,
but I cannot find a grammar for the language, not even a clear description
of the tokens.  Some specific points:
    it appears that Turbo Prolog accepts \n, \t, \", \', and \\
    escapes in characters and strings, but that it also accepts
    \ddd -- one to three DECIMAL digits.  That's what I infer from
    the code, however the manual is quite explicit that anything
    other than \n or \t will be mapped to itself, so \9 should be 9,
    not a tab.

    some parts of the code are sloppy with variable names, e.g. a
    clause will have "Text" and "TEXT".  Now the Turbo manual is
    explicit (when you find it!) that case doesn't matter in
    predicate names, but I cannot find anything about whether case
    is significant in variable names.

    Declarations in 2.0 are more complex than they used to be, but
    I can find no summary of their syntax.

One thing I have learned from this program is that Turbo Prolog's
static typing appears to have played a significant part in shaping
a very inefficient program.  (That was very carefully worded.)

-- 
Fear most of all to be in error.	-- Kierkegaard, quoting Socrates.