Solution
= Solution
For posets $A,B$, let $B^A$ be the poset of monotone maps $A\to B$ ordered pointwise. Evaluation
$$
B^A\times A\to B,\qquad(f,a)\mapsto f(a)
$$
is monotone. A monotone map $h:C\times A\to B$ curries to the monotone map
$$
\widehat h:C\to B^A,\qquad
\widehat h(c)(a)=h(c,a),
$$
and this correspondence is natural and invertible. Thus the <cartesian closed category of posets> has exponentials $B^A$.