What can I do if a tag is no longer available?

I spent many hours getting Haskell-IDE-Integration working with ghc-863 (lts-13.10). The Haskell IDE Integration package actually will not compile without this version. I see the package is available as ghc863Binary, but not as tag ghc863. Further, when I install the ghc863Binary tag, it installs, but is not recognized by the Haskell Nix integration, which is specifically looking for the tag ‘ghc863’. I have rolled back my generation to get back off of 864, which sort-of works, but error persists:

stack repl
error: attribute 'ghc863' missing, at (string):1:48
(use '--show-trace' to show detailed location information)

I’m trying to figure out whether I should file a bug report somewhere or if this is something I can still fix. Thanks.

I think I found a solution, went back to ghc844 (lts-12.20) and am using the wrapper version of hie. I can avoid this problem for now, but it’s still unclear to me what to do about a tag that goes missing.

You may want to “pin” nixpkgs, but I don’t know your exact setup, so its hard to tell you exactly what to do. Anyway

with import (builtins.fetchGit {
url = https://github.com/NixOS/nixpkgs;
ref = “master”;
rev = 4f2d842a98ebc4b1d393e6061f30a4e726220b47;
}); haskell.packages.ghc863

should give you the haskell package set with ghc863, as 863 was still present at 4f2d842a98ebc4b1d393e6061f30a4e726220b47.

Edit: use correct hash :-/

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