schell@ws:~/Desktop/Link to COG366$ swipl
Welcome to SWI-Prolog (threaded, 64 bits, version 7.4.2)
SWI-Prolog comes with ABSOLUTELY NO WARRANTY. This is free software.
Please run ?- license. for legal details.

For online help and background, visit http://www.swi-prolog.org
For built-in help, use ?- help(Topic). or ?- apropos(Word).

?- consult('proglang.pro').
true.

?- listing(language).
language(smalltalk).
language(lisp).
language(prolog).

?- listing(essence).
essence(smalltalk, objects, 'message passing').
essence(lisp, lists, 'recursive functions').
essence(prolog, relations, 'logical inferencing').

?- listing(history).
history(smalltalk, inventor('Alan Kay'), date(1980)).
history(lisp, inventor('John McCarthy'), date(1959)).
history(prolog, inventor('Alan Colmeraur'), date(1971)).

?- halt.
schell@ws:~/Desktop/Link to COG366$