From a8b73528413cbdfbb50a29e1ef7dc18037c49009 Mon Sep 17 00:00:00 2001
From: Daniel Firth <daniel.firth@iohk.io>
Date: Mon, 12 Feb 2024 11:48:01 +0000
Subject: [PATCH] Use fmt shell in treefmt job

---
 .github/workflows/formatting.yaml |  2 +-
 nix/hydra/shell.nix               | 18 ++++++++++++++++--
 2 files changed, 17 insertions(+), 3 deletions(-)

diff --git a/.github/workflows/formatting.yaml b/.github/workflows/formatting.yaml
index 2e74f3a1ec9..8e206879ba8 100644
--- a/.github/workflows/formatting.yaml
+++ b/.github/workflows/formatting.yaml
@@ -26,4 +26,4 @@ jobs:
 
     - name: 📐 Check code formatting
       run: |
-        nix develop .#ci --command treefmt --fail-on-change
+        nix develop .#fmt --command treefmt --fail-on-change
diff --git a/nix/hydra/shell.nix b/nix/hydra/shell.nix
index 501dc8cfa13..57aa818ff52 100644
--- a/nix/hydra/shell.nix
+++ b/nix/hydra/shell.nix
@@ -14,6 +14,9 @@ let
 
   cabal = pkgs.haskell-nix.cabal-install.${compiler};
 
+  fourmolu = pkgs.haskell-nix.tool compiler "fourmolu" "0.14.0.0";
+  cabal-fmt = pkgs.haskell-nix.tool compiler "cabal-fmt" "0.1.9";
+
   # Build HLS form our fork (see flake.nix)
   haskell-language-server = pkgs.haskell-nix.tool compiler "haskell-language-server" rec {
     src = inputs.hls;
@@ -39,8 +42,8 @@ let
     pkgs.haskellPackages.hspec-discover
     # Formatting
     pkgs.treefmt
-    (pkgs.haskell-nix.tool compiler "fourmolu" "0.14.0.0")
-    (pkgs.haskell-nix.tool compiler "cabal-fmt" "0.1.9")
+    fourmolu
+    cabal-fmt
     pkgs.nixpkgs-fmt
     # For validating JSON instances against a pre-defined schema
     pkgs.check-jsonschema
@@ -145,6 +148,16 @@ let
     ];
   };
 
+  fmtShell = pkgs.mkShell {
+    name = "hydra-format-shell";
+    buildInputs = [
+      pkgs.treefmt
+      fourmolu
+      cabal-fmt
+      pkgs.nixpkgs-fmt
+    ];
+  };
+
   # If you want to modify `Python` code add `libtmux` and pyyaml to the
   # `buildInputs` then enter it and then run `Python` module directly so you
   # have fast devel cycle.
@@ -159,4 +172,5 @@ in
   cabalOnly = cabalShell;
   exes = exeShell;
   demo = demoShell;
+  fmt = fmtShell;
 }