lix/corepkgs/nar/unnar.fix

Function(["nar", "name"],
  Package(
    [ ("name", Var("name"))
    , ("build", Relative("nar/unnar.sh"))
    , ("nar", Var("nar"))
    , ("id", Var("id"))
    ]
  )
)
* The policy-free derivate sharing now almost works. :-) For any hash for which no local expansion is available, Nix can execute a `substitute' which should produce a path with such a hash. This is policy-free since Nix does not in any way specify how the substitute should work, i.e., it's an arbitrary (unnormalised) fstate expression. For example, `nix-pull' registers substitutes that fetch Nix archives from the network (through `wget') and unpack them, but any other method is possible as well. This is an improvement over the old Nix sharing scheme, which had a policy (fetching through `wget') built in. The sharing scheme doesn't work completely yet because successors from fstate rewriting have to be registered on the receiving side. Probably the whole successor stuff can be folded up into the substitute mechanism; this would be a nice simplification. 2003-07-10 15:11:48 +00:00			`Function(["nar", "name"],`
			`Package(`
			`[ ("name", Var("name"))`
			`, ("build", Relative("nar/unnar.sh"))`
			`, ("nar", Var("nar"))`
* Substitutes now should produce a path with the same id as they are substituting for (obvious, really). * For greater efficiency, nix-pull/unnar will place the output in a path that is probably the same as what is actually needed, thus preventing a path copy. * Even if a output id is given in a Fix package expression, ensure that the resulting Nix derive expression has a different id. This is because Nix expressions that are semantically equivalent (i.e., build the same result) might be different w.r.t. efficiency or divergence. It is absolutely vital for the substitute mechanism that such expressions are not used interchangeably. 2003-07-22 15:15:15 +00:00			`, ("id", Var("id"))`
* The policy-free derivate sharing now almost works. :-) For any hash for which no local expansion is available, Nix can execute a `substitute' which should produce a path with such a hash. This is policy-free since Nix does not in any way specify how the substitute should work, i.e., it's an arbitrary (unnormalised) fstate expression. For example, `nix-pull' registers substitutes that fetch Nix archives from the network (through `wget') and unpack them, but any other method is possible as well. This is an improvement over the old Nix sharing scheme, which had a policy (fetching through `wget') built in. The sharing scheme doesn't work completely yet because successors from fstate rewriting have to be registered on the receiving side. Probably the whole successor stuff can be folded up into the substitute mechanism; this would be a nice simplification. 2003-07-10 15:11:48 +00:00			`]`
			`)`
			`)`