WIP, memoize lazy evaluation wrappers

.gitignore

@@ -1,2 +1,3 @@
 node_modules
 private-notes.txt
+old

run.js

@@ -4,6 +4,7 @@ const fs = require("fs");
 const assert = require("assert");
 
 const transpile = require("./src/transpile");
+const measureTime = require("./src/astformer/util/measure-time");
 
 assert(process.argv[2] != null);
 
@@ -12,13 +13,34 @@ const nixFile = fs.readFileSync(nixFilePath, "utf8");
 
 let transpiled = transpile(nixFile);
 
+const api = {
+	builtins: {},
+	$$jsNix$memoize: function (func) {
+		let isCalled = false;
+		let storedResult;
+
+		return function (arg) {
+			if (isCalled === false) {
+				storedResult = func(arg);
+				isCalled = true;
+			}
+
+			return storedResult;
+		};
+	}
+};
+
+// TODO: Switch to Node `vm` API instead, and check whether there's a polyfill for it for non-Node environments, build a custom one if not
+const context = { module: {}, exports: {} };
+context.module.exports = exports;
+
+new Function("module", transpiled)(context.module);
+
 console.log("-- EVALUATION RESULT:");
 
-console.log(eval(transpiled)({
-	builtins: {},
-	$$jsNix$extend: function (base, props) {
-		let newObject = Object.create(base);
-		Object.assign(newObject, props);
-		return newObject;
-	}
-}));
+// Warm-up for hot VM performance testing
+// for (let i = 0; i < 10000; i++) {
+// 	context.module.exports(api);
+// }
+
+console.log(measureTime(() => context.module.exports(api)));

src/astformer/util/measure-time.js

@@ -1,5 +1,7 @@
 "use strict";
 
+// FIXME: Make separate package, measure-function-call or so
+
 function hrtimeToNanoseconds(time) {
 	// If the numbers here become big enough to cause loss of precision, we probably have bigger issues than numeric precision...
 	return (time[0] * 1e9) + time[1];

src/transformers/attribute-sets.js

@@ -13,7 +13,7 @@ let tmplCallLazy = template(`
 `);
 
 let tmplLazyWrapper = template(`(
-	() => %%expression%%
+	$$jsNix$memoize(() => %%expression%%)
 )`);
 
 let tmplLazyWrapperRecursive = template(`(

src/transformers/functions.js

@@ -34,7 +34,7 @@ let tmplFunctionCall = template(`
 
 // NOTE: Duplicated from `attribute-sets` for now
 let tmplLazyWrapper = template(`(
-	() => %%expression%%
+	$$jsNix$memoize(() => %%expression%%)
 )`);
 
 function functionDefinition({ universal, formals, body }) {

src/transformers/index.js

@@ -17,20 +17,11 @@ const printAst = require("../print-ast");
 
 // FIXME: Make strict mode! Otherwise objects will inherit from `global`
 let tmplModule = template(`
-	module.exports = function({ builtins, $$jsNix$extend }) {
+	module.exports = function({ builtins, $$jsNix$memoize }) {
 		return %%contents%%;
 	};
 `);
 
-
-let tmplLetIn = template(`
-	(() => {
-		%%letBindings%%
-
-		return %%expression%%;
-	})()
-`);
-
 let tmplObjectDynamic = template(`
 	(() => {
 		let $$nixJS_object = {};