chore(ops): make nix package for mina_txn_hasher

nix-env -if ops/mina/mina_txn_hasher.nix
mina_txn_hasher.exe --help

Justfile

@@ -83,7 +83,7 @@ lint:
   # standardrb --no-fix ops/*.rb
   shellcheck tests/regression.bash
   @echo "--- Linting Nix configs"
-  alejandra --check flake.nix
+  alejandra --check flake.nix ops/mina/mina_txn_hasher.nix
   @echo "--- Linting Rust code"
   cd rust && time cargo {{nightly_if_required}} fmt --all --check
   cd rust && time cargo clippy --all-targets --all-features \
@@ -109,7 +109,7 @@ format:
   cd rust && cargo {{nightly_if_required}} fmt --all
   # standardrb --fix ops/*.rb
   shfmt --write ops/*.sh
-  alejandra flake.nix
+  alejandra flake.nix ops/mina/mina_txn_hasher.nix
 
 # Perform a fast verification of whether the source compiles.
 check:

ops/mina/mina_txn_hasher.nix

@@ -0,0 +1,24 @@
+with import <nixpkgs> {}; let
+  deps = [
+    jemalloc
+    openssl
+    libffi
+    gmp
+    gcc.cc.lib
+  ];
+in
+  stdenv.mkDerivation {
+    name = "mina_txn_hasher";
+    src = ./.;
+
+    dontConfigure = true;
+    dontBuild = true;
+
+    nativeBuildInputs = [autoPatchelfHook];
+    buildInputs = deps;
+
+    installPhase = ''
+      mkdir -p $out/bin
+      install -Dm755 mina_txn_hasher.exe $out/bin/mina_txn_hasher.exe
+    '';
+  }