This is a sample session with the CLP( 
) system.
Some extra information is given using comments after the % character.
% clpr
CLP(R) Version 1.2
(c) Copyright International Business Machines Corporation
1989 (1991) All Rights Reserved
1 ?- f(X,Y) = f(g(A),B). % some simple ``unification''
B = Y
X = g(A)
*** Yes
2 ?- X = Y + 4 , Y = Z - 3, Z = 2. % simple arithmetic evaluation
Z = 2
Y = -1
X = 3
*** Yes
3 ?- X + Y < Z, 3 * X - 4 * Y = 4, 3 * X + 2 * Y = 1.
Y = -0.5
X = 0.666667
0.166667 < Z
*** Yes
4 ?- X + Y < Z, 3 * X - 4 * Y = 4, 2 * X + 3 * Z = 1.
Y = -1.125*Z - 0.625
X = -1.5*Z + 0.5
-0.0344828 < Z
*** Yes
5 ?- history.
1 f(X, Y) = f(g(A), B).
2 X = Y + 4, Y = Z - 3, Z = 2.
3 X + Y < Z, 3 * X - 4 * Y = 4, 3 * X + 2 * Y = 1.
4 X + Y < Z, 3 * X - 4 * Y = 4, 2 * X + 3 * Z = 1.
*** Yes
6 ?- 2. % run second goal again
X = Y + 4, Y = Z - 3, Z = 2.
Z = 2
Y = -1
X = 3
*** Yes
7 ?- ['examples/fib']. % consult (load) a program
>>> Sample goal: go/0
*** Yes
8 ?- ls fib. % look at the program
fib(0, 1).
fib(1, 1).
fib(N, X1 + X2):-
N > 1,
fib(N - 1, X1),
fib(N - 2, X2).
*** Yes
9 ?- fib(5,F). % only one answer to this
F = 8
*** Retry?;
*** No
10 ?- F > 7, F < 9, fib(N,F). % only ask for the first answer
N = 5
F = 8
*** Retry?
11 ?- [`'examples/mortgage']. % use "`" to reconsult
>>> Sample goals: go1/0, go2/0
*** Yes
12 ?- ls. % look at the entire rulebase
h:-
history.
fib(0, 1).
fib(1, 1).
fib(N, X1 + X2):-
N > 1,
fib(N - 1, X1),
fib(N - 2, X2).
go:-
printf(\nFib(14) = , []),
ztime,
fib(14, X),
ctime(T1),
printf(% (Time = %)\n, [X, T1]),
printf(Fib-1(610) = , []),
ztime,
fib(Y, 610),
ctime(T2),
printf(% (Time = %)\n, [Y, T2]).
mg(P, T, I, B, MP):-
T = 1,
B = P + P * I - MP.
mg(P, T, I, B, MP):-
T > 1,
mg(P * (1 + I) - MP, T - 1, I, B, MP).
go1:-
ztime,
mg(999999, 360, 0.01, 0, M),
ctime(T),
printf(Time = %, M = %\n, [T, M]).
go2:-
ztime,
mg(P, 720, 0.01, B, M),
ctime(T),
printf(Time = %\n, [T]),
dump([P, B, M]).
*** Yes
13 ?- [`'examples/mortgage'].
Warning: mg/5 has been redefined
>>> Sample goals: go1/0, go2/0
*** Yes
14 ?- ls.
h:-
history.
fib(0, 1).
fib(1, 1).
fib(N, X1 + X2):-
N > 1,
fib(N - 1, X1),
fib(N - 2, X2).
go:-
printf(\nFib(14) = , []),
ztime,
fib(14, X),
ctime(T1),
printf(% (Time = %)\n, [X, T1]),
printf(Fib-1(610) = , []),
ztime,
fib(Y, 610),
ctime(T2),
printf(% (Time = %)\n, [Y, T2]).
mg(P, T, I, B, MP):-
T = 1,
B = P + P * I - MP.
mg(P, T, I, B, MP):-
T > 1,
mg(P * (1 + I) - MP, T - 1, I, B, MP).
go1:-
ztime,
mg(999999, 360, 0.01, 0, M),
ctime(T),
printf(Time = %, M = %\n, [T, M]).
go2:-
ztime,
mg(P, 720, 0.01, B, M),
ctime(T),
printf(Time = %\n, [T]),
dump([P, B, M]).
*** Yes
15 ?- go2.
Time = 0.25
M = -7.74367e-06*B + 0.0100077*P
*** Retry?
16 ?- [user].
p(X) :- writeln(X).
^D
*** Yes
17 ?- p(hello).
hello
*** Yes