Ch4s3

defmodule Testing do
  """
  You can pipe straight into a case
  Kernel.<<>>, the special form for binary pattern
  matching can be used in a case match to 
  split up incoming binaries, like this 
  imaginary |~ delimited protocol.
   
    "fiexd_size_header|~some message"
    

Ch4s3

@doc """
You can pipe queries into this build_where/3
fn and match on operators like :in, :==,
:ilike, etc and handle the particular
where semantics in each function case.
Pay attention to the positional binding 
[...,e] which will capture the last 
binding added to the piped in query.
See also: https://hexdocs.pm/ecto/Ecto.Query.html#module-positional-bindings
and.      https://hexdocs.pm/ecto/Ecto.Query.API.html#field/2

Ch4s3

from(c in City, select: c) # returns the schema as a struct
from(c in City, select: {c.name, c.population}) # returns Tuple of {name, population}
from(c in City, select: [c.name, c.county]) # returns List of [name, county] 
from(c in City, select: %{n: c.name, answer: 42}) # returns Map with keys :n, and :answer
from(c in City, select: %{c | alternative_name: c.name}) # returns the schema as a Struct with :alternative_name added
from(c in City, select: %Data{name: c.name}) # returns the selected name in %Data{}

Ch4s3

defmodule MyApi.Schema.Pipeline.MyCompilePhase do
  @moduledoc """
  based on Absinthe phases https://hexdocs.pm/absinthe/1.5.3/Absinthe.Phase.html
  """

  alias Absinthe.{Blueprint, Pipeline, Phase}
  alias Absinthe.Blueprint.Schema.{ObjectTypeDefinition, FieldDefinition}

  def pipeline(pipeline) do
    Pipeline.insert_after(pipeline, Phase.Schema.TypeImports, __MODULE__)

Ch4s3

file_changes="$(git diff --name-only $(git merge-base master HEAD))"
migration_files="$(echo $file_changes | grep -c /migrations/)"
application_files="$(echo $file_changes | grep -c -v /migrations/ --include \*.ex --include \*.exs)"

echo "checking for migrations and apllication changes"

if (($migration_files == 0)) && (($application_files > 0));
then
  echo "Only Application Changes. OK"
  exit 0

Ch4s3

defmodule Boggle do

  def full_match(dictionary, word) do
    case Enum.member?(dictionary, word) do
      true -> word
      false -> nil
    end

  end

Ch4s3

namespace :json do
  desc 'Export all data to JSON files'
  task :export => :environment do
    Rails.application.eager_load!

    ApplicationRecord.descendants.each do |model|
      next if model.table_name.nil? || model.table_name == ''
      begin
        data = model.all
        next if data == []

Ch4s3

class DoubleStack
  attr_accessor :inbox, :outbox
  def initialize
    @inbox = []
    @outbox = []
  end

  def enqueue(item)
    @inbox << item
  end

Ch4s3

#################################
# Top-down recursive merge sort
#################################

#################################
# Worst-case perf O(n log n)
# Bestt-case perf O(n log n)
# Worst-case space complexity O(n)
#################################

Ch4s3

def find_suffix(collection, query_string)
  # Inject 0 so that when evaluating the block, you have
  # and object that responds to `+`
  # if the array element is equal to the query_string 
  # add to the sum and return the sum to be used in 
  # the next step
  collection.inject(0) { |sum, str| sum += 1 if str == query_string; sum }
end