Using cuts in Prolog -

i trying find of distinct entries person's name john, peter or fred.

however, if there were, example, 2 people called peter, want display 1 occurrence of name.

my code far follows:

searchpeople(x) :-    people(_,[x|_]),    x=john; x=peter; x=fred.

i understand solution cuts (having read other posts), cannot find example cuts used when trying retrieve x or y or z (in case john, peter or fred).

thanks in advance.

the problem you're confusing operator precedence. more conventional programming languages writing this

if ( , b or c or d ) ...

is going in trouble, code has exact same problem. operator precedence , associativity causes

searchpeople(x) :-   people(_,[x|_]) ,   x=john ;   x=peter ;   x=fred .

to parsed if written

searchpeople(x) :-   ( people(_,[x|_]) ,     x = john   ) ;   ( x = peter ;     x = fred   ) .

which not intended.

while could use parenthesis effect want:

searchpeople(x) :-   people(_,[x|_]) ,   ( x = john ;     x = peter ;     x = fred   ) .

you better off splitting things bit:

search_people(x) :-     people(_,[x|_]) ,     desired_person(x).  desired_person(john). desired_person(peter). desired_person(fred).

it makes intent clearer , easier understand. it's easier debug , extend.

Print F