Set a return value in prolog

Question

I am trying to write simple case in mod function of two peano's number in prolog , put some case it give me wrong answer I don't know what is the problem with my code

simple case is if C smaller than D return C

mod(C,D,F):- smaller(C,D) -> mod(C,D,C).

I don't have output

thank you.

If C is smaller than D (smaller(C, D) succeeds), then you recursively check if C is C modulo D (you call mod(C,D,C), which will go into an infinite recursion. A big clue here is your result should be F but you make no reference to F in your predicate clause. I'm sure you saw the singleton variable warning for F. What do you really want to happen if smaller(C, D) succeeds? (HINT: you want F to be something.) — lurker
yes i want to check if this condition correct c smaller than d return c — joshua

Jay Joshi Jay Joshi · Accepted Answer · 2017-12-02T11:21:32

By simply doing this:-

mod(C,D,C):- smaller(C,D)

It will return C if smaller predicate returns true, that is when C is smaller than D.

Set a return value in prolog

1 Answers