0.2.0

Author: rksm

doc/rationale.md

@@ -0,0 +1,74 @@
+# Rationale
+
+lively.modules provides a framework for loading, defining and interactively
+modifying JavaScript modules. A module is an entity containing JavaScript
+source code that adheres to the definition of the 
+[ECMAScript Language Specification](https://tc39.github.io/ecma262/#sec-modules).
+
+## Live development
+
+lively.modules provides an interface to support interactive development with
+[es6 modules](http://exploringjs.com/es6/ch_modules.html). In particular it
+allows to capture the runtime state (internal variables and definitions) of
+modules to allow to access local state when evaluating code in module contexts.
+It also allows to iteratively update the runtime state of a module (e.g.
+modifying a function or adding a new definition) and will take care that
+dependencies are updated accordingly.
+
+## Packages
+
+Since the EcmaScript standard does not define a package concept (package = set
+of modules belonging togeter), lively.modules adds a very lightweight
+convention for identifying and loading packages that is mostly based on
+the [npm package conventions](https://docs.npmjs.com/how-npm-works/packages).
+
+This is crucial because es6 modules leave name resolution open to the
+[module loader implementation](https://tc39.github.io/ecma262/#sec-hostresolveimportedmodule).
+
+Consider an import statement like
+
+```js
+import { foo } from 'some-package/bar.js';
+```
+
+To what specific resource (modules don't need to be files!)
+`'some-package/bar.js'` is resolved is up to the loader, i.e. up to
+lively.modules. Using the package concept we can have simple conventions that
+define how a resource like `some-package` can be found.
+
+## Lively ecosystem
+
+A flexible and lightweight notion of packages can help us to make Lively more
+"approachable", meaning that the system can be broken into clearly defined
+sub-systems thus reducing the complexity of an otherwise monolothic syste,
+Also, those package can be re-used outside the main Lively system.
+
+## Debugging
+
+The main problem we faced when implementing the source-transformation-based
+debugging approach was code management: Once the number of modules approaches
+non-trivial numbers it becomes a resource intensive task to manage rewritten
+and original code in a way that is performant enough for convenient interactive
+development. This especially posed a problem b/c the semnatics of JavaScript
+allow lexical scoping and with that "hiding" internal module state. Once a
+not-transformed conventional JS "module" is defined there is no generic way to
+instrument it later.
+
+es6 modules provide a new restriction between modules: Module boundaries are
+clear and can be statically determined. Imports and exports are restricted to
+well defined notion of bindings that allows live updates and circular
+references. By treating modules as "black boxes", a source-transformation
+debugger can gradually transform modules, redefining them but maintaining their
+exported state.
+
+## PartsBin
+
+A tension that exists in the PartsBin workflow up to this point is the mix of
+state (think "binary" blobs of serialized objects) and source code. So far, the
+existing Lively module system and serialized objects don't share a common
+concept, making them harder to learn and use. Modules and packages might offer
+an interesting alternative: Since a module can be any kind of resource, not
+just JS statements, we can mix code and serialized objects in our package
+concept. This would allow to combine both approaches from the ground up.
+
+...

package.json

@@ -1,6 +1,6 @@
 {
   "name": "lively.modules",
-  "version": "0.1.7",
+  "version": "0.2.0",
   "main": "dist/lively.modules.js",
   "scripts": {
     "test": "mocha-es6 tests/*-test.js",