  We construct an explicit family of linear rank-metric codes over any field
${\mathbb F}_h$ that enables efficient list decoding up to a fraction $\rho$ of
errors in the rank metric with a rate of $1-\rho-\epsilon$, for any desired
$\rho \in (0,1)$ and $\epsilon > 0$. Previously, a Monte Carlo construction of
such codes was known, but this is in fact the first explicit construction of
positive rate rank-metric codes for list decoding beyond the unique decoding
radius.
  Our codes are subcodes of the well-known Gabidulin codes, which encode
linearized polynomials of low degree via their values at a collection of
linearly independent points. The subcode is picked by restricting the message
polynomials to an ${\mathbb F}_h$-subspace that evades the structured subspaces
over an extension field ${\mathbb F}_{h^t}$ that arise in the linear-algebraic
list decoder for Gabidulin codes due to Guruswami and Xing (STOC'13). This
subspace is obtained by combining subspace designs contructed by Guruswami and
Kopparty (FOCS'13) with subspace evasive varieties due to Dvir and Lovett
(STOC'12).
  We establish a similar result for subspace codes, which are a collection of
subspaces, every pair of which have low-dimensional intersection, and which
have received much attention recently in the context of network coding. We also
give explicit subcodes of folded Reed-Solomon (RS) codes with small folding
order that are list-decodable (in the Hamming metric) with optimal redundancy,
motivated by the fact that list decoding RS codes reduces to list decoding such
folded RS codes. However, as we only list decode a subcode of these codes, the
Johnson radius continues to be the best known error fraction for list decoding
RS codes.
