From 343d3b6508f73440ae205329a2e069f7a465d4fd Mon Sep 17 00:00:00 2001
From: Daniel Barlow <dan@telent.net>
Date: Tue, 12 Sep 2023 17:45:18 +0100
Subject: [PATCH] writeFennel is writeFennelScript with knobs on

The second parameter is now an options attrset, wherein we will pile
all kinds of cool stuff.

Right now the only cool bit is `mainFunction`, which allows you to
compile a fennel module into a lua script and name the function that
should be executed when the script runs. This makes it easier to
write testable Fennel code, because the test script can require the
module and call stuff in it.
---
 pkgs/default.nix                     |  1 +
 pkgs/write-fennel-script/default.nix | 26 ++-----------------
 pkgs/write-fennel/default.nix        | 37 ++++++++++++++++++++++++++++
 3 files changed, 40 insertions(+), 24 deletions(-)
 create mode 100644 pkgs/write-fennel/default.nix

diff --git a/pkgs/default.nix b/pkgs/default.nix
index 1c52a63..e1fa46c 100644
--- a/pkgs/default.nix
+++ b/pkgs/default.nix
@@ -52,6 +52,7 @@ in {
     };
   };
   writeFennelScript = callPackage ./write-fennel-script {};
+  writeFennel = callPackage ./write-fennel {};
   writeAshScript = callPackage ./write-ash-script {};
   systemconfig = callPackage ./systemconfig {};
   s6-init-bin =  callPackage ./s6-init-bin {};
diff --git a/pkgs/write-fennel-script/default.nix b/pkgs/write-fennel-script/default.nix
index dfe36f4..09e46c4 100644
--- a/pkgs/write-fennel-script/default.nix
+++ b/pkgs/write-fennel-script/default.nix
@@ -2,30 +2,8 @@
   lua
 , lib
 , fennel
+, writeFennel
 , stdenv
 }:
 name : packages : source :
-  let
-    luapath = builtins.map
-      (f:
-        "${f}/share/lua/${lua.luaversion}/?.lua;" +
-        "${f}/share/lua/${lua.luaversion}/?/init.lua;")
-      packages;
-    luacpath = builtins.map (f: "${f}/lib/lua/${lua.luaversion}/?.so;") packages;
-  in stdenv.mkDerivation {
-    inherit name;
-    src = ./.;
-    nativeBuildInputs = [ fennel ];
-    buildPhase = ''
-      (
-       echo "#!${lua}/bin/lua"
-       echo "package.path = ${lib.strings.escapeShellArg (builtins.concatStringsSep "" luapath)} .. package.path"
-       echo "package.cpath = ${lib.strings.escapeShellArg (builtins.concatStringsSep "" luacpath)} .. package.cpath"
-       fennel --correlate --compile ${source}
-      ) >  ${name}.lua
-    '';
-    installPhase = ''
-      cp ${name}.lua $out
-      chmod +x $out
-    '';
-  }
+writeFennel name { inherit packages; } source
diff --git a/pkgs/write-fennel/default.nix b/pkgs/write-fennel/default.nix
new file mode 100644
index 0000000..c9be23e
--- /dev/null
+++ b/pkgs/write-fennel/default.nix
@@ -0,0 +1,37 @@
+{
+  lua
+, lib
+, fennel
+, stdenv
+}:
+name :
+{
+  packages ? [],
+  correlate ? false,
+  mainFunction ? null
+} @ options : source :
+  let
+    luapath = builtins.map
+      (f:
+        "${f}/share/lua/${lua.luaversion}/?.lua;" +
+        "${f}/share/lua/${lua.luaversion}/?/init.lua;")
+      packages;
+    luacpath = builtins.map (f: "${f}/lib/lua/${lua.luaversion}/?.so;") packages;
+    luaFlags = lib.optionalString (mainFunction !=null) "-e dofile(arg[0]).${mainFunction}()";
+  in stdenv.mkDerivation {
+    inherit name;
+    src = ./.;
+    nativeBuildInputs = [ fennel ];
+    buildPhase = ''
+      (
+       echo "#!${lua}/bin/lua ${luaFlags}"
+       echo "package.path = ${lib.strings.escapeShellArg (builtins.concatStringsSep "" luapath)} .. package.path"
+       echo "package.cpath = ${lib.strings.escapeShellArg (builtins.concatStringsSep "" luacpath)} .. package.cpath"
+       fennel ${if correlate then "--correlate" else ""} --compile ${source}
+      ) >  ${name}.lua
+    '';
+    installPhase = ''
+      cp ${name}.lua $out
+      chmod +x $out
+    '';
+  }