Add regenerate-nixpkgs.sh

regenerate-nixpkgs.sh

@@ -0,0 +1,69 @@
+#! /usr/bin/env bash
+
+# This script finds the last generation of hackage-packages.nix in nixpkgs and
+# rebuilds it based on the configuration-hackage2nix.yaml in nixpkgs.
+# Assumptions
+
+# 1. Have cabal installed.
+# 2. Being run out of the cabal2nix repo.
+# 3. A checkout or symlink to checkout of nixpkgs under ./nixpkgs
+# 4. A checkout or symlink to checkout of all-cabal-hashes under ./hackage
+
+# What you should do:
+# 1. Change pkgs/development/haskell-modules/configuration-hackage2nix.yaml to your liking.
+# 2. Run ./regenerate-nixpkgs.sh
+# 3. Enjoy your adapted pkgs/development/haskell-modules/hackage-packages.nix
+
+
+# Possible improvements for this script:
+# 1. Use nix-shell to provide dependencies.
+# 2. Clone all-cabal-hashes if missing.
+# 3. Share code with update-nixpkgs.
+# 4. Integrate preferred-versions into hackage2nix.
+# 5. Use cabal tarballs in hackage2nix.
+
+set -eu
+
+exit_trap()
+{
+  local lc="$BASH_COMMAND" rc=$?
+  test $rc -eq 0 || echo "*** error $rc: $lc"
+}
+
+trap exit_trap EXIT
+
+cd "$(dirname "$0")"
+
+cd nixpkgs
+msg=$(git log pkgs/development/haskell-modules/hackage-packages.nix | grep -A1 -B6 "This update was generated by hackage2nix .* from Hackage revision" | head -n8)
+nixpkgsCommit=$(echo $msg | sed 's/.*commit \([a-z0-9]*\).*/\1/')
+nixpkgsCommitDate=$(echo $msg | sed 's/.*Date: \(.*\) hackage-packages.nix.*/\1/')
+usedCabal2nix=$(echo $msg | sed 's/.*hackage2nix .*-g\(.*\) from Hackage revision.*/\1/')
+usedCabalHashes=$(echo $msg | sed 's/.*all-cabal-hashes\/commit\/\(.*\)\./\1/')
+echo "Last commit updating hackage-packages.nix was $nixpkgsCommit at $nixpkgsCommitDate."
+export NIX_PATH=nixpkgs=$PWD
+cd ..
+echo "Checking out $usedCabal2nix for cabal2nix ..."
+git fetch --all -q
+git checkout $usedCabal2nix -q
+cabal2nix=$(git describe --dirty)
+echo "Checked out."
+
+cd hackage
+echo "Checking out $usedCabalHashes for hackage ..."
+git fetch --all -q
+git checkout $usedCabalHashes -q
+echo "Checked out."
+rm -f preferred-versions
+for n in */preferred-versions; do
+  cat >>preferred-versions "$n"
+  echo >>preferred-versions
+done
+hackage=$(git rev-parse --verify HEAD)
+cd ..
+
+# This command needs a recent development version of cabal-install. I don't
+# think this works properly in version 2.0.0.0 already.
+echo "Running hackage2nix on nixpkgs ..."
+cabal -v0 new-run hackage2nix -- --nixpkgs="$PWD/nixpkgs" +RTS -M4G -RTS
+echo "hackage-packages.nix regenerated."