[eclipse-users] Interval constraints

Dear all,

In the tutorial of ECLiPSe I currently study, there is the following
example at chapter 8:

?- X :: -10 .. 10.

In my ECLiPSe version when I copy out it literally I get an error:
string stream 27: syntax error: postfix/infix operator expected
| [X]::-1..10
|      ^ here

I found that probably the parentheses are missed because if I try to run
?- X ::(-10 .. 10).
it works fine. For positive numbers (without minus ahead) both version 
work correctly.

Is it the real cause of the problem ?

Best regards,
Wojciech Pieprzyca