🚀 go-pugleaf

I've used AAIS Prolog for more than a year, and I am reasonably happy
with it.  Programs that works under C-Prolog or SICS Prolog MAY need
a little bit of modification before it can run under AAIS.  The major
differences are:

1) The I/O predicates, such as get0/1 and read/1, fails when end of file
   is reached.  In SICS, get0/1 will return a -1 and read/1 will return
   end_of_file when end of file is reached.  (This may be nice sometimes.)

2) AAIS has predicates such as append/3 and member/2 built in.  However,
   you can make the system forget about such built-ins by using the new/2
   directive as follows:
	:- new(append, 3).
	:- new(member, 2).
   In porting a program that consists of several files, just create a
   file that consults everything, and put the new/2 directives at the
   top of this file.

3) File naming convention is different, if you move from a UNIX to the
   Mac environment, and if you want to use files not in the current
   directory.

4) AAIS implements the clause/2 predicate a little bit differently.
   For example, if you have the following clause in the database:
	a :- b, c.
   When you do clause(a, X), X will become [b, c], instead of the
   usual b, c.  This may be the biggest problem when you want to
   port something to AAIS.

Other than 4), porting is not a big problem.  What basically needs to
be done is to create a Mac specific file that handles the differences.

Some of the good things:

1) AAIS is very robust, I don't recall that I've ever got any crashes.

2) It handles GARBAGE COLLECTION.  You can also disable/enable the
   garbage collection messages.

3) Although it does not have a compiler, it runs a little bit slower
   than the C-Prolog on our departmental VAX.

4) It has interface to the Mac toolbox, so graphics is possible,
   although I've never tried it.

5) It has a familiar Mac application user interface.  It's not like
   a product of a garage operation.

6) Very nice debugger.  It even pretty-prints the current goal, so
   things don't disappear into the right edge of the screen or have
   unreadable wrap around.

7) It catches user interrupt (<Cmd>.), just like C-Prolog or SICS
   handles <CNTRL>C.

8) It's inexpensive.  When I bought it, I cost about $99 or $95.
   The price must have gone up.  However, to get a full language
   system for less than $150 is a very good price.  Also, their
   support is pretty good.  When I wrote to them, they actually responded.

***Disclaimer:  I am in no way associated with Advanced A.I. Systems Inc.***