Working ocaml using unstable

nix/base-system/flake.lock

@@ -571,7 +571,8 @@
         "runwhen-flake": "runwhen-flake",
         "rust-overlay-flake": "rust-overlay-flake",
         "sile-flake": "sile-flake",
-        "treesitter-context": "treesitter-context"
+        "treesitter-context": "treesitter-context",
+        "unstable": "unstable"
       }
     },
     "roslyn-lsp": {
@@ -780,6 +781,20 @@
         "rev": "e6b743ccd4e780bc9cd85b707de67df72eea1a23",
         "type": "github"
       }
+    },
+    "unstable": {
+      "locked": {
+        "lastModified": 1706367331,
+        "narHash": "sha256-AqgkGHRrI6h/8FWuVbnkfFmXr4Bqsr4fV23aISqj/xg=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "160b762eda6d139ac10ae081f8f78d640dd523eb",
+        "type": "github"
+      },
+      "original": {
+        "id": "nixpkgs",
+        "type": "indirect"
+      }
     }
   },
   "root": "root",

nix/base-system/flake.nix

@@ -2,6 +2,7 @@
   inputs = {
     # Default to sane nixpkgs versions
     nixpkgs.url = "github:nixos/nixpkgs/23.11";
+    unstable.url = "nixpkgs";
     nixpkgs-darwin.url = "github:nixos/nixpkgs/nixpkgs-23.11-darwin";
     darwin = {
       url = "github:lnl7/nix-darwin";
@@ -55,6 +56,7 @@
     d2-vim-src,
     treesitter-context,
     roslyn-lsp,
+    unstable,
     ... # We don't use the self or nixpkgs args here so we just glob it.
   }: 
   rec {
@@ -195,6 +197,7 @@ EOF";
       jj = jj-flake.packages."${system}".jujutsu;
       age = agenix-flake.packages."${system}".default;
       nurl = nurl-flake.packages."${system}".default;
+      unstablePkgs = import unstable { inherit system; };
     in { config, pkgs, ... }: let
         d2-lang = pkgs.callPackage ./d2.nix {};
 	in {
@@ -282,9 +285,9 @@ EOF";
             dotnet-sdk_7
             netcoredbg
             powershell
-            ocaml
-            #opam # TODO(jwall): See if there is a way to pin this to a working version.
-            ocamlformat
+            unstablePkgs.ocaml
+            unstablePkgs.opam
+            unstablePkgs.ocamlformat
             # TODO(jwall): I include these initially for nvim telescope
             ripgrep
             fd