Move function spdxLicense, internally used in yarn2nix
to lib/meta.nix, and
rename to getLicenseFromSpdxId
A similar function is implemented in poetry2nix,
but the one originally in yarn2nix seems beter.
since it falls back to an license-like attrset
for mismatched case
instead of a plain string
The way I see it, there's no point in the argument being there if it can't be used.
Right now its lack currently prevents a workaround for an issue I can't wrap my head around - first encountered [here](https://logs.nix.samueldr.com/nixos-dev/2019-08-28#2532857;).
The generated yarnNix file doesn't need to be part of the mkDerivation.
And doing so prevents other platforms from reproducibly instantiating
it. With this change you can e.g. do
darwinPkgs.yarn2nix.mkYarnPackage {
# ...
yarnNix = pkgs.yarn2nix.mkYarnNix {
yarnLock = ./yarn.lock;
};
}
Which is a darwin derivation, but can still be instantiated reproducibly on Linux.
