Fix nix build (forgot it was building from git source); patch to load module & put fns in module

default.nix

@@ -1,40 +1,10 @@
 {pkgs ? import <nixpkgs> {}}:
 pkgs.stdenv.mkDerivation {
   name = "riverguile";
-  src = pkgs.fetchgit {
-    url = "https://git.sr.ht/~leon_plickat/riverguile/";
-    rev = "744ce4b1eb5950d0dc795d64bfac6b7738eec6f1";
-    hash = "sha256-80XVaq+17Vu+DAs7pjt3cu5wiK37680A7S6qIulPRLc=";
-  };
-  patches = [
-    (pkgs.writeText "nix-build.patch" ''
-diff --git a/Makefile b/Makefile
-index 915f7ac..ff2b3c2 100644
---- a/Makefile
-+++ b/Makefile
-@@ -1,6 +1,6 @@
- SCANNER := wayland-scanner
- 
--PREFIX=/usr/local
-+PREFIX=''${out}
- BINDIR=$(PREFIX)/bin
- DATADIR=$(PREFIX)/share
- MODULEDIR=$(DATADIR)/guile/3.0
-diff --git a/src/call-idle-handler.c b/src/call-idle-handler.c
-index 727656e..b4d4474 100644
---- a/src/call-idle-handler.c
-+++ b/src/call-idle-handler.c
-@@ -8,7 +8,7 @@ static void *call_idle_handler_inner (void *data)
- 	struct Call_idle_handler_parameters *params =
- 		(struct Call_idle_handler_parameters *)data;
- 
--	SCM event;
-+	SCM event = { 0 };
- 	switch (params->event)
- 	{
- 		case IDLE:   event = scm_from_utf8_symbol("idle");   break;
-'')
-  ];
-  buildInputs = with pkgs; [wayland-scanner wayland guile];
-  nativeBuildInputs = [pkgs.pkg-config];
+  src = ./.;
+  preFixup = ''
+    wrapProgram $out/bin/riverguile --set GUILE_LOAD_PATH "$out/share/guile/3.0/" 
+  '';
+  buildInputs = with pkgs; [wayland guile];
+  nativeBuildInputs = with pkgs; [pkg-config makeBinaryWrapper wayland wayland-scanner];
 }