add lua operators

lib.nix

@@ -75,6 +75,26 @@ let
   set = variable: value: join " = " [ (raw variable) value ];
   lset = variable: value: join " " [ (raw "local") (set variable value) ];
 
+  op = operation: left: right: concat [ (raw "(") (join " ${operation} " [ left right ]) (raw ")") ];
+
+  add = op "+";
+  sub = op "-";
+  mul = op "*";
+  div = op "/";
+  mod = op "%";
+  exp = op "^";
+
+  eq = op "==";
+  ne = op "~=";
+  gt = op ">";
+  lt = op "<";
+  gte = op ">=";
+  lte = op "<=";
+
+  and = op "and";
+  or = op "or";
+  not = expr: join " " [ (raw "not") expr ];
+
   isLuaNil = expr: getType expr == "nil";
   LuaNil = { _type = "nil"; };
 
@@ -129,4 +149,12 @@ in
   inherit LuaNil;
   inherit raw join concat concatLines pipe;
   inherit namedField call require set lset;
+
+  inherit op;
+  inherit eq ne gt lt gte lte;
+  inherit add sub mul div mod exp;
+  inherit and or not;
+
+  # useful alias
+  var = raw;
 }

lib.test.nix

@@ -148,4 +148,18 @@ with nix2lua; pkgs.lib.runTests {
     expr = toLua (lset "parser_config.d2" { });
     expected = "local parser_config.d2 = {  }";
   };
+  "test returns all operations" = {
+    expr = toLua (concatLines [
+      (eq (mul (add 1 2) (sub 2 1)) 3)
+      (not (eq (mul (add 1 2) (sub 2 1)) 3))
+      (not 10)
+      (gt 10 5)
+    ]);
+    expected = ''
+      (((1 + 2) * (2 - 1)) == 3)
+      not (((1 + 2) * (2 - 1)) == 3)
+      not 10
+      (10 > 5)
+    '';
+  };
 }