feat (shells): haskell, java, switch to unstable

shells/why3-dev/flake.lock

@@ -0,0 +1,27 @@
+{
+  "nodes": {
+    "nixpkgs": {
+      "locked": {
+        "lastModified": 1767116409,
+        "narHash": "sha256-5vKw92l1GyTnjoLzEagJy5V5mDFck72LiQWZSOnSicw=",
+        "owner": "nixos",
+        "repo": "nixpkgs",
+        "rev": "cad22e7d996aea55ecab064e84834289143e44a0",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nixos",
+        "ref": "nixos-unstable",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "root": {
+      "inputs": {
+        "nixpkgs": "nixpkgs"
+      }
+    }
+  },
+  "root": "root",
+  "version": 7
+}

shells/why3-dev/flake.nix

@@ -2,7 +2,7 @@
   description = "Nix flake devshell for why3 development";
 
   inputs = {
-    nixpkgs.url = "github:nixos/nixpkgs/nixos-25.11";
+    nixpkgs.url = "github:nixos/nixpkgs?ref=nixos-unstable";
   };
 
   outputs =
@@ -23,11 +23,9 @@
             ocamlPackages.menhir
             ocamlPackages.menhirLib
             ocamlPackages.zarith
+            ocamlPackages.lablgtk3
+            ocamlPackages.lablgtk3-sourceview3
           ];
-
-          shellHook = ''
-            echo "Test.";
-          '';
         };
     };
 }