plan.json should contain the Hackage revision number

[amigalemming]

I use plan.json to generate Flatpak manifests. Flatpak expects immutable sources fixed by hashes, e.g.:

{
  "url": "https://hackage.haskell.org/package/integer-logarithms-1.0.3/integer-logarithms.cabal",
  "type": "file",
  "sha256": "21cdc5661958a703303d2b430220908db8c2c42dbc58db0d7baac1d171f31768"
}

However, the Cabal file may change due to an update to the Cabal file. Thus I would actually need to specifiy the URL:
https://hackage.haskell.org/package/integer-logarithms-1.0.3/revision/1.cabal

But plan.json does not tell the revision where its pkg-cabal-sha256 refers to.
Please add the revision number to plan.json.
Or is there an easy way to retrieve this information from 01-index.tar and friends?

[hvr]

The problem is that the revision number is a bit of an contextual information that emerges only once you know exactly which repository the .cabal file comes from (it's basically the occurence count within the stream of package index events)

However, I do have an add-on tool which allows efficient reverse-lookups of the sha256 to revision-numbering, if you're interested...

[amigalemming]

I'd prefer a library interface, but a command-line tool would be ok for now.

[amigalemming]

On Tue, 27 Aug 2019, Herbert Valerio Riedel wrote: The problem is that the revision number is a bit of an contextual information that emerges only once you know exactly which repository the .cabal file comes from (it's basically the occurence count within the stream of package index events)

Do you mean that Cabal is not able to provide this information or do you mean that it is not reasonable to write this information to plan.json?