aliases.rb

# encoding: utf-8

module Kernel
  alias :λ :lambda
end

class Hash
  alias :+ :merge
  alias :<< :merge!
end

aliases_spec.rb

# encoding: utf-8
require './aliases.rb'

describe 'cool aliases' do

  describe 'lambda' do

    it 'works with a regular call' do
      p = lambda do
        true
      end
      p.call.should == true
    end

    it 'works with an aliased call' do
      p = λ do # unicode 03BB
        true
      end
      p.call.should == true
    end

  end

  describe 'hash methods' do
    describe '+' do
      it 'concatenates two arrays' do
        ([1] + [2]).should == [1,2]
      end

      it 'concatenates two hashes, aliasing merge' do
        ({a: 1} + {b: 2}).should == {a: 1, b: 2}
      end

      it 'makes a new object' do
        a = {a: 1}
        b = {b: 2}

        (a + b).should == {a: 1, b: 2}
        (a + b).object_id.should_not == a.object_id
      end
    end

    describe '<<' do
      it 'smooshes an item into an array' do
        ([1] << 2).should == [1,2]
      end

      it 'smooshes one hash into another, aliasing merge!' do
        ({a: 1} << {b: 2}).should == {a: 1, b: 2}
      end

      it 'mutates the original left-side object' do
        a = {a: 1}
        b = {b: 2}

        (a << b).should == {a: 1, b: 2}
        (a << b).object_id.should == a.object_id
      end

      it 'overwrites the left side with the right side' do
        ({a: 1} << {a: 2}).should == {a: 2}
      end
    end
  end
end

todo: π = Math::PI