Add --minify

[kazuho]

Add support for minification at the JSX compiler level, for better compression ratio and ease of use.

Background: JavaScript-level minifiers have problem in efficiency and maintaining compatibility, since it cannot use any type information (i.e. property names that need to be preserved needs to be listed, and those listed would never get minified even when possible).

Note: introduce export attribute for classes / functions of which names should be preserved so that they would be callable from JavaScript.

[kazuho]

The work is ongoing on kazuho/experiments/minify4.

[kazuho]

Support for minification (turned on by specifying "--minify" as a compile option) has been introduced to master at commit dc3f7cc.

There should be no side-effects to the generated code (when to using --minify) expect for the fact that support for annocated comments targeting the Google Closure Compiler minifier has been dropped (Google Closure Compiler should continue to work wo. type annotations).

Things yet to be done:

• do not emit unused code
• merge identical strings
• adjust the code emitter for certain expressions (e.g. instanceof) so that the generated code would be shorter

[kazuho]

A brief description of the minification and export rules can be found at https://github.com/jsx/JSX/wiki/Minification-and-export-rules

[kazuho]

Closing the issue as finished.

• do not emit unused code
• merge identical strings
• adjust the code emitter for certain expressions (e.g. instanceof) so that the generated code would be shorter

Regarding these three leftovers, work on the first has been finished (see #157). It would be preferable to work on the other two as well, but they are considered low priority since they would only have small effect in terms of code size.

[gfx]

Ho about combination of --minify and --enable-source-map?

[kazuho]

@gfx
Thank you for pointing that out. Opened a separate issue.

[gfx]

👍