Configure the Haskell package set for ghc-9.0.x.

pkgs/development/haskell-modules/configuration-ghc-9.0.x.nix

@@ -0,0 +1,46 @@
+{ pkgs, haskellLib }:
+
+with haskellLib;
+
+self: super: {
+
+  # This compiler version needs llvm 10.x.
+  llvmPackages = pkgs.llvmPackages_10;
+
+  # Disable GHC 9.0.x core libraries.
+  array = null;
+  base = null;
+  binary = null;
+  bytestring = null;
+  Cabal = null;
+  containers = null;
+  deepseq = null;
+  directory = null;
+  exceptions = null;
+  filepath = null;
+  ghc-bignum = null;
+  ghc-boot = null;
+  ghc-boot-th = null;
+  ghc-compact = null;
+  ghc-heap = null;
+  ghc-prim = null;
+  ghci = null;
+  haskeline = null;
+  hpc = null;
+  integer-gmp = null;
+  libiserv = null;
+  mtl = null;
+  parsec = null;
+  pretty = null;
+  process = null;
+  rts = null;
+  stm = null;
+  template-haskell = null;
+  terminfo = null;
+  text = null;
+  time = null;
+  transformers = null;
+  unix = null;
+  xhtml = null;
+
+}