If you don't like interactive queries, you can
suppress most (all?) of them.
(%i3) limit(a*x,x,inf);
Is a positive, negative, or zero?
pos;
(%o3) INF
(%i4) assume_pos : true$
(%i5) assume_pos_pred : lambda([x],true)$
(%i6) limit(a*x,x,inf);
(%o6) INF
(%i7) integrate(exp(-a*x),x,0,inf);
(%o7) 1/a
I think the 'assume_pos' mechanism is dangerous.
Maybe those of you that dislike interactive queries
might like it better than I do.
Barton