% for statement from T Van Le 92
for(I,I,N):-I =< N.
for(I,M,N):-M < N, M1 is M+1, for(I,M1,N).

for(I,N):-for(I,1,N).
sample('for(I,1,10),  write(I), nl, fail!').

go:-for(I,1,10),  write(I), nl, fail.