Merge pull request #67 from jvelez1/ruby/_with_lambdas

Ruby with lambdas

Author: josevalim

ruby/with_lambdas.rb

@@ -0,0 +1,42 @@
+require 'json'
+
+sections = [
+  {
+    "title": "Getting started",
+    "reset_lesson_position": false,
+    "lessons": [
+      {"name": "Welcome"},
+      {"name": "Installation"}
+    ]
+  },
+
+  {
+    "title": "Basic operator",
+    "reset_lesson_position": false,
+    "lessons": [
+      {"name": "Addition / Subtraction"},
+      {"name": "Multiplication / Division"}
+    ]
+  },
+
+  {
+    "title": "Advanced topics",
+    "reset_lesson_position": true,
+    "lessons": [
+      {"name": "Mutability"},
+      {"name": "Immutability"}
+    ]
+  }
+]
+
+reset_lesson_position = lambda {|lessons| lessons.each.with_index(1) { |lesson, index|  lesson.merge!(position: index) } }
+
+modify_section = lambda do |section, indexed_lessons|
+  lessons = section[:reset_lesson_position] ? reset_lesson_position.call(section[:lessons]) : indexed_lessons
+  section.merge!(lessons: lessons) 
+end
+
+indexed_sections = sections.flat_map{ _1[:lessons] }.each.with_index(1) { |a, index|  a.merge!(position: index) }
+sections.map { |section| modify_section.call(section, indexed_sections.shift(section[:lessons].count)) }
+
+puts JSON.pretty_generate(sections)