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.

?- language(snobol).
true.

?- language(snowball).
false.

?- essence(snobol,DT,_).
DT = pattern.

?- essence(L,array,_).
false.

?- language(L).
L = smalltalk ;
L = lisp ;
L = prolog ;
L = snobol ;
L = apl.

?- language(L),write(L),nl,fail.
smalltalk
lisp
prolog
snobol
apl
false.

?- history(apl,inventor(Name),_),write(Name),nl,fail.
Kenneth Iverson
false.

?- history(_,inventor(I),_).
I = 'Alan Kay' ;
I = 'John McCarthy' ;
I = 'Alan Colmeraur' ;
I = 'Ralph Griswold' ;
I = 'Kenneth Iverson'.

?- history(_,inventor(I),_),write(I),nl,fail.
Alan Kay
John McCarthy
Alan Colmeraur
Ralph Griswold
Kenneth Iverson
false.

?- history(L,_,date(1959)),essence(L,lists,_).
L = lisp .

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