add writeFennelScript function, make ifwait use it

pkgs/default.nix

@@ -11,6 +11,7 @@
       kernel = callPackage ./kernel {};
     };
   };
+  writeFennelScript = callPackage ./write-fennel-script {};
   writeAshScript = callPackage ./write-ash-script {};
   systemconfig = callPackage ./systemconfig {};
   s6-init-bin =  callPackage ./s6-init-bin {};

pkgs/ifwait/default.nix

@@ -1,34 +1,13 @@
 {
   luaSmall
 , netlink-lua
-, stdenv
-, makeWrapper
+, writeFennelScript
+, runCommand
 }:
 let
   lua = luaSmall;
   netlink = netlink-lua.override {inherit lua;};
-  fennel = lua.pkgs.fennel;
-in stdenv.mkDerivation rec {
-  pname = "ifwait";
-  version = "1";
-  phases = [ "installPhase" ];
-
-  buildInputs = [ lua netlink ];
-  nativeBuildInputs = [ makeWrapper fennel ];
-
-  LUA_CPATH = "${netlink}/lib/lua/${lua.luaversion}/\?.so"; # for nix-shell
-
-  installPhase = ''
-    mkdir -p $out/bin $out/lib
-    fennel --compile  ${./ifwait.fnl} > $out/lib/${pname}.lua
-
-    makeWrapper ${lua}/bin/lua $out/bin/${pname} \
-      --prefix LUA_CPATH ";" ${netlink}/lib/lua/${lua.luaversion}/\?.so \
-      --add-flags $out/lib/${pname}.lua
-    # makeWrapper adds a shebang for bash
-    sed -i -e '1c#!/bin/sh' $out/bin/${pname}
-  '';
-}
-
-# to use fennel.view,
-#  --prefix LUA_PATH ";" ${fennel}/share/lua/5.2/\?.lua \
+in runCommand "ifwait" {} ''
+  mkdir -p $out/bin
+  cp -p ${writeFennelScript "ifwait" [netlink] ./ifwait.fnl} $out/bin/ifwait
+''

pkgs/write-fennel-script/default.nix

@@ -0,0 +1,21 @@
+{
+  runCommand
+, luaSmall
+, runtimeShell
+, lib
+}:
+let lua = luaSmall;
+in name : packages : source :
+  let
+    luapath = builtins.map (f: "${f}/share/lua/${lua.luaversion}/?.lua;") packages;
+    luacpath = builtins.map (f: "${f}/lib/lua/${lua.luaversion}/?.so;") packages;
+    in runCommand name {} ''
+      #!${runtimeShell}
+      (
+      echo "#!${lua}/bin/lua"
+      echo "package.path = ${lib.strings.escapeShellArg luapath} .. package.path"
+      echo "package.cpath = ${lib.strings.escapeShellArg luacpath} .. package.cpath"
+      ${lua.pkgs.fennel}/bin/fennel --compile  ${source}
+      ) > $out
+      chmod a+x $out
+    ''

tests/ci.nix

@@ -5,4 +5,5 @@
   pppoe = import ./pppoe/test.nix;
   jffs2 =  import ./jffs2/test.nix;
   min-copy-closure =  import ./min-copy-closure/test.nix;
+  fennel = import ./fennel/test.nix;
 }

tests/fennel/hello.fnl

@@ -0,0 +1 @@
+(print "hello")

tests/fennel/test.nix

@@ -0,0 +1,21 @@
+{
+  liminix
+, nixpkgs
+}:
+let
+  overlay = import "${liminix}/overlay.nix";
+  pkgs = import <nixpkgs> { overlays = [overlay]; };
+  script = pkgs.writeFennelScript "foo" [] ./hello.fnl;
+  inherit (pkgs.luaSmall.pkgs) fifo;
+  netlink = pkgs.netlink-lua.override { lua = pkgs.luaSmall; };
+  script2 = pkgs.writeFennelScript "foo2" [fifo netlink] ./hello.fnl;
+in pkgs.runCommand "check" {
+  } ''
+set -e
+# test that it works
+test $(${script}) = "hello"
+# test that lua path, cpath are set
+grep -q ${fifo}/share/lua/5.3 ${script2}
+grep -q ${netlink}/lib/lua/5.3 ${script2}
+date > $out
+''