Prolog4

rec :- consult('prog.pro').

comp(Elem1,Elem2,CompFunc) :-
	atom(CompFunc),
	Term =.. [CompFunc,Elem1,Elem2],
	call(Term).

even(N) :- 0 is N mod 2.

filter([],[],_).
filter([H1|T1],[H2|T2],FiltFunc) :-
	atom(FiltFunc),
	Term =.. [FiltFunc,H1],
	call(Term), !,
	H1 = H2,
	filter(T1,T2,FiltFunc).
filter([_|T],Lst,FiltFunc) :-
	filter(T,Lst,FiltFunc).

foldl(X,_,[],X) :- !.
foldl(X,Func,[H|T],Res) :-
	Term =.. [Func,X,H,R],
	call(Term),
	foldl(R,Func,T,Res).

minus(A,B,C) :- C is A-B.

addHead(El,Orig,[[El|L]|T2]) :-
	var(Orig), !,
	Orig = [L|T1],
	addHead(El,T1,T2).
addHead(_,[],Res) :- !, Res = [].
addHead(El,[L|T1],[[El|L]|T2]) :-
	addHead(El,T1,T2).