the-undefined

defmodule Ejixir do
  def j_tl(coll) do
    [ _h | t ] = coll
    t
  end

  def j_hd(coll) do
    [ h | _t ] = coll
    h
  end

the-undefined

import Html exposing (div, text)
import Html.App as App
import Html.Events exposing (onClick)

type Msg = Increment

main : Program Never
main =
    App.beginnerProgram
        { model = 0

the-undefined

# frozen_string_literal: true
module DomHelper
  # Executes the given block within the context of a specific node identified
  # using its data-xxx attributes. It will take any number of arguments.
  #
  # eg:
  #   user = create_user()
  #   within_element(id: user.id) do
  #     click_on 'Edit'
  #   end

the-undefined

[commit]
  template = ~/.gitmessage

the-undefined

def char_combinations(s)
  length = s.size
  list_comp = Array.new(length) do |start_index|
    length.times.inject([]) do |combinations, end_index|
      sub_str = s[start_index..end_index]
      sub_str.size > 0 ? combinations << sub_str : combinations
    end
  end.flatten
end

the-undefined

require 'date'

# OK: but the bracket faries are in abundence :()
((Date.today)..(Date.today + 7)).to_a

# BAD: for performance
# https://github.com/bbatsov/rubocop/blob/58761c6bbb0ba68f78651df672b93f9c15e1213f/lib/rubocop/cop/performance/times_map.rb
7.times.map { |n| Date.today + n }

# GOOD: concise, clear & performant

the-undefined

# Example of a guard clause performing a nil check
class BlahSpeaker
  has_one :audience
  
  def speak
    return if audience.nil?
    audience.address('blah ' * 100)
  end
end

the-undefined

TimeWindow.where(%{EXTRACT(YEAR FROM start_date) = ?}, 2020)

the-undefined

$ irb
001:0> Class.new.initialize
NoMethodError: private method `initialize' called for #<Class:0x007fc9188e3f08>

the-undefined

class Presenter
  include SortableColumns
  
  def sortable_column_heading(text:, attr:, &block)
    label = sort_link_text(text, attr)
    link_params = sort_link_params(attr)
    
    block.call(label, link_params)
  end