  We use the classical version of the density-functional theory in the
weighted-density approximation to build up the entire phase diagram and the
interface structure of a two-dimensional lattice-gas model which is known, from
previous studies, to possess three stable phases -- solid, liquid, and vapour.
Following the common practice, the attractive part of the potential is treated
in a mean-field-like fashion, although with different prescriptions for the
solid and the fluid phases. It turns out that the present theory, compared to
similar theories in the continuum, is of worse quality. Nevertheless, at least
a number of qualitative facts are reproduced correctly: i) the existence of
three phases; ii) the disappearance of the liquid phase when the range of the
attraction is progressively reduced; and iii) the intrusion, just below the
triple-point temperature, of a liquid-like layer at the interface between the
coexisting solid and vapour phases.
