{stdenv, darcs, nix}: {url, tag ? null, md5, partial ? true}:
stdenv.mkDerivation {
name = "fetchdarcs";
builder = ./builder.sh;
buildInputs = [darcs nix];
partial = if partial then "--partial" else "";
# Nix <= 0.7 compatibility.
id = md5;
outputHashAlgo = "md5";
outputHashMode = "recursive";
outputHash = md5;
inherit url tag;
}