Forall and a terminology question

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It seems to me that you asked for foreach/2:

?- length(L,Len), foreach(between(1,Len,N),nth1(N,L,N)).
L = [],
Len = 0 ;
L = [1],
Len = 1 ;
L = [1, 2],
Len = 2 ;
L = [1, 2, 3],
Len = 3 ;
L = [1, 2, 3, 4],
Len = 4 ;
L = [1, 2, 3, 4, 5],
Len = 5 ;
L = [1, 2, 3, 4, 5, 6],
Len = 6 ;
L = [1, 2, 3, 4, 5, 6, 7],
Len = 7 

?- L=[A,A,A], length(L,Len), foreach(between(1,Len,N),nth1(N,L,N)).
false.

?- L=[A,B,C], length(L,Len), foreach(between(1,Len,N),nth1(N,L,N)).
L = [1, 2, 3],
A = 1,
B = 2,
C = Len, Len = 3.

For the name example - in the real world this would of course be much simpler:

funny_word("Clown").
funny_word("Joker").

name_example(FirstName, LastName) :- 
    funny_word(FirstName),
    funny_word(LastName).

But for the sake of the question I think you look for something like this:


name_key(surname).
name_key(forename).

has_name(Key,Value,Names) :-
    member(Key-Value, Names).

names(Names) :-
    foreach(name_key(Key),
	    (
		funny_word(Name),		
		has_name(Key,Name,Names)	    
	    )).

Example:

?- length(N,_), names(N).
N = [surname-"Clown", forename-"Clown"] ;
N = [forename-"Clown", surname-"Clown"] ;
N = [surname-"Joker", forename-"Joker"] ;
N = [forename-"Joker", surname-"Joker"]

(Note that you need the has_name/3 predicate or something similar, because just plugging in member(Key-Name,Names) doesn’t work: Foreach bug?

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