Define an operator in prolog

Question

I need to define a new operator that associates in the following way

 (1 newop 2) / (2 newop) / a

The parenthesis were just used to give an understanding of the associativity of the new op

So.

:- op(A, B, newop).

Which would be the values for A and B.

Thanks in advance.

I think it's impossible. Do you want to discriminate number vs atom ? — CapelliC, Jun 01 '14 at 17:19

false · Answer 1 · 2014-06-01T17:41:28.543

What you want is that newop serves both as an infix operator as in (1 newop 2) and as a postfix operator as in (2 newop).

This is impossible in ISO Prolog. In subclause 6.3.4.3 of ISO/IEC 13211-1:1995 it is stated:

There shall not be an infix and a postfix operator with the same name.

That said, there are implementations that still permit this. However, be aware that such implementations ofter differ in subtle ways.

score 0 · Answer 2 · answered Jun 01 '14 at 17:19

0

infix operator: xfx

precende should be higher than "/"

precende for / is 400

 :- op (300, xfx, newop).

answered Jun 01 '14 at 17:19

Alessandroempire

That takes care of the infix case on your original example, but not the post fix case. – lurker Jun 02 '14 at 10:03

2 Answers2