  Affine $\lambda$-terms are $\lambda$-terms in which each bound variable
occurs at most once and linear $\lambda$-terms are $\lambda$-terms in which
each bound variables occurs once. and only once. In this paper we count the
number of closed affine $\lambda$-terms of size $n$, closed linear
$\lambda$-terms of size $n$, affine $\beta$-normal forms of size $n$ and linear
$\beta$-normal forms of ise $n$, for different ways of measuring the size of
$\lambda$-terms. From these formulas, we show how we can derive programs for
generating all the terms of size $n$ for each class. For this we use a specific
data structure, which are contexts taking into account all the holes at levels
of abstractions.
