chore(users/gs/owothia): remove unnecessary overrides, simplify

* chatter and its dependencies have been fixed in upstream
  haskellPackages, so we can get rid of the packageSet.nix expression:
  https://github.com/NixOS/nixpkgs/pull/116803

* Merged default.nix and pkg.nix into one expression and use
  callCabal2nix instead of emulating it with nested imports.

* Minor refactor of shell.nix and remove haskell-language-server
  until we've redone it or replaced it with the upstream one as now the
  GHC versions are out of sync: hls is built with 8.8.4, but
  haskellPackages uses 8.10.4

Change-Id: Ie75eaa93ba8bd79e749e2442fb28c855b8a15a1d
Reviewed-on: https://cl.tvl.fyi/c/depot/+/2661
Tested-by: BuildkiteCI
Reviewed-by: glittershark <grfn@gws.fyi>

users/glittershark/owothia/default.nix

@@ -1,6 +1,4 @@
-{ pkgs ? (import ../../../. {}).third_party
-, lib ? pkgs.lib
-, ...
-}:
+{ pkgs ? (import ../../../. {}).third_party, ... }:
 
-(import ./packageSet.nix {}).callPackage (import ./pkg.nix { inherit pkgs; }) {}
+pkgs.haskellPackages.callCabal2nix "owothia"
+  (pkgs.gitignoreSource ./.) { }

users/glittershark/owothia/packageSet.nix

@@ -1,22 +0,0 @@
-{ pkgs ? (import ../../../. {}).third_party, ... }:
-
-let
-
-  hlib = pkgs.haskell.lib;
-
-in
-
-# overlay can be removed when this is in our pin:
-# https://github.com/NixOS/nixpkgs/pull/116803
-pkgs.haskellPackages.extend (self: super: {
-  regex-tdfa-text = hlib.doJailbreak
-    (hlib.appendPatch
-      super.regex-tdfa-text
-      ./regex-tdfa-text.patch
-    );
-
-  fullstop = hlib.dontCheck super.fullstop;
-
-  chatter = hlib.doJailbreak
-    (hlib.dontCheck (hlib.appendPatch super.chatter ./chatter.patch));
-})

users/glittershark/owothia/pkg.nix

@@ -1,6 +0,0 @@
-args@{ pkgs ? (import ../../../. {}).third_party }:
-
-import ((import ./packageSet.nix args).haskellSrc2nix {
-  name = "owothia";
-  src = pkgs.gitignoreSource ./.;
-})

users/glittershark/owothia/shell.nix

@@ -1,14 +1,23 @@
-args@{ pkgs ? (import ../../../. {}).third_party, ... }:
+{ pkgs ? (import ../../../. {}).third_party, ... }:
 
-((import ./packageSet.nix args).extend (pkgs.haskell.lib.packageSourceOverrides {
-  owothia = pkgs.gitignoreSource ./.;
+let
+  inherit (pkgs)
+    haskellPackages
+    haskell
+    gitignoreSource
+    ;
+in
+
+(haskellPackages.extend (haskell.lib.packageSourceOverrides {
+  owothia = gitignoreSource ./.;
 })).shellFor {
-  packages = p: [p.owothia];
+  packages = p: [ p.owothia ];
   withHoogle = true;
   doBenchmark = true;
-  buildInputs = with pkgs.haskellPackages; [
+  buildInputs = with haskellPackages; [
     cabal-install
     hlint
-    pkgs.haskell-language-server.ghc884
+    # TODO(sterni): versions out of sync
+    # pkgs.haskell-language-server.ghc884
   ];
 }