Get rid of Sprockets and use Tilt

This improves development tremendously - while live reload doesn't work now
(but manually refreshing page does) the development load times are much much
better, especially connected with recent improvements to Opal::Builder.
Also, source maps now work correctly.

Ref: opal/opal#2479

Author: hmdne

.gitignore

@@ -3,3 +3,5 @@ build/*
 .idea
 .ruby-version
 .sass-cache
+tmp
+app/application.js

Gemfile

@@ -1,18 +1,17 @@
 source "https://rubygems.org"
 
-gem "opal", "~> 1.4a"
-gem "opal-sprockets"
+gem "opal", "~> 1.4a", git: "https://github.com/opal/opal", ref: "hmdne/fix-builder-dup"
 gem "opal-browser"
 gem "middleman"
 gem "middleman-livereload"
 gem "middleman-syntax"
-gem "middleman-sprockets"
 gem "middleman-blog"
 gem "middleman-gh-pages"
 gem "redcarpet"
 gem "sass"
 gem "webrick"
 gem "terser"
+gem "tilt", git: "https://github.com/rtomayko/tilt"
 
 group :test do
   gem "rspec"

Gemfile.lock

@@ -1,3 +1,18 @@
+GIT
+  remote: https://github.com/opal/opal
+  revision: 04009f35baa561b99a91d92702d0e07f19b058e1
+  ref: hmdne/fix-builder-dup
+  specs:
+    opal (1.6.0)
+      ast (>= 2.3.0)
+      parser (~> 3.0, >= 3.0.3.2)
+
+GIT
+  remote: https://github.com/rtomayko/tilt
+  revision: a8b10cae56606ba657eeb9a06f1077155909c425
+  specs:
+    tilt (2.0.11)
+
 GEM
   remote: https://rubygems.org/
   specs:
@@ -103,9 +118,6 @@ GEM
       em-websocket (~> 0.5.1)
       middleman-core (>= 3.3)
       rack-livereload (~> 0.3.15)
-    middleman-sprockets (4.1.1)
-      middleman-core (~> 4.0)
-      sprockets (>= 3.0)
     middleman-syntax (3.3.0)
       middleman-core (>= 3.2)
       rouge (~> 3.2)
@@ -116,16 +128,9 @@ GEM
     nokogiri (1.13.10)
       mini_portile2 (~> 2.8.0)
       racc (~> 1.4)
-    opal (1.6.0)
-      ast (>= 2.3.0)
-      parser (~> 3.0, >= 3.0.3.2)
     opal-browser (0.3.3)
       opal (>= 1.0, < 2.0)
       paggio (>= 0.3.0)
-    opal-sprockets (1.0.3)
-      opal (>= 1.0, < 2.0)
-      sprockets (~> 4.0)
-      tilt (>= 1.4)
     padrino-helpers (0.15.1)
       i18n (>= 0.6.7, < 2)
       padrino-support (= 0.15.1)
@@ -174,14 +179,10 @@ GEM
     sassc (2.4.0)
       ffi (~> 1.9)
     servolux (0.13.0)
-    sprockets (4.1.1)
-      concurrent-ruby (~> 1.0)
-      rack (> 1, < 3)
     temple (0.9.1)
     terser (1.1.12)
       execjs (>= 0.3.0, < 3)
     thor (1.2.1)
-    tilt (2.0.11)
     toml (0.3.0)
       parslet (>= 1.8.0, < 3.0.0)
     tzinfo (2.0.5)
@@ -205,16 +206,15 @@ DEPENDENCIES
   middleman-blog
   middleman-gh-pages
   middleman-livereload
-  middleman-sprockets
   middleman-syntax
-  opal (~> 1.4a)
+  opal (~> 1.4a)!
   opal-browser
-  opal-sprockets
   puma
   redcarpet
   rspec
   sass
   terser
+  tilt!
   webrick
 
 BUNDLED WITH

config.rb

@@ -1,6 +1,11 @@
 require 'bundler'
 Bundler.require
 
+# Build Opal part with Tilt, with our customized pipeline
+require 'opal-config'
+
+set :rb, builder: OpalBuilder.new
+
 # Enable the collector extension, used to create
 # try_ruby_<language>.json  files
 require 'collector'
@@ -14,7 +19,6 @@
     smartypants: true
 
 activate :syntax
-activate :sprockets
 
 activate :blog do |blog|
   blog.publish_future_dated = true
@@ -27,13 +31,6 @@
 set :css_dir, 'stylesheets'
 set :js_dir, 'javascripts'
 
-after_configuration do
-  sprockets.append_path "#{__dir__}/app"
-  Opal.paths.each do |p|
-    sprockets.append_path p
-  end
-end
-
 configure :development do
   set :debug_assets, true
   activate :livereload

opal-config.rb

@@ -0,0 +1,9 @@
+require 'tilt/opal'
+
+Opal.append_path "#{__dir__}/app"
+
+class OpalBuilder < Opal::Builder
+  def to_s
+    super + "\n" + source_map.to_data_uri_comment
+  end
+end

source/javascripts/application.js

@@ -0,0 +1 @@
+require "try_ruby"