test: Summer example

examples/basics/summer.pl

@@ -0,0 +1,22 @@
+summer(Start, End, 0) :- Start == End.
+summer(Start, End, Sum) :-
+    Start \== End,
+    Next is Start + 1,
+    summer(Next, End, Rest),
+    writeln(rest(Rest)),
+    Sum is Start + Rest,
+    writeln(sum(Sum)).
+
+my_sum :-
+    write('Enter start: '),
+    read(Start),
+    write('Enter end: '),
+    read(End),
+    summer(Start, End, Sum),
+    write('The sum is: '),
+    write(Sum), nl.
+
+main :-
+    summer(1, 5, Sum).
+
+:- initialization(main).