  We present a practical and accurate density functional for the
exchange-correlation energy of electrons in two dimensions. The exchange part
is based on a recent two-dimensional generalized-gradient approximation derived
by considering the limits of small and large density gradients. The fully local
correlation part is constructed following the Colle-Salvetti scheme and a
Gaussian approximation for the pair density. The combination of these
expressions is shown to provide an efficient density functional to calculate
the total energies of two-dimensional electron systems such as semiconductor
quantum dots. Excellent performance of the functional with respect to
numerically exact reference data for quantum dots is demonstrated.
