JoelQ

view : Model -> Html Msg
view model =
  div []
    [ div [ class "icon" ] [ span [class "icon-profile" ] [] ]
    , div [ class "icon" ] [ span [ class "icon-clock" ] [] ]
    ]
    
-- REFACTOR TO

view : Model -> Html Msg

JoelQ

class NonEmptyArray
  include Enumerable

  def initialize(first, rest)
    @first = first
    @rest = rest
  end

  def first
    @first

JoelQ

Problem

You have a graph where the nodes are in groups. You want to create edges between all nodes that are in different groups.

For example, given the following groups:

[[1, 2], [3], [4, 5]]

JoelQ

class Hamming
  def self.zip_count(s1, s2)
    s1.chars.
      zip(s2.chars).
      count { |c1, c2| c1 != c2 }
  end

  def self.for_loop(s1, s2)
    distance = 0

JoelQ

class Hamming
  def self.eager(s1, s2)
    s1.chars.
      zip(s2.chars).
      count { |c1, c2| c1 != c2 }
  end

  def self.half_lazy(s1, s2)
    s1.each_char.
      zip(s2.each_char).

JoelQ

class Hamming
  def self.eager(s1, s2)
    s1.chars.take(10).
      zip(s2.chars.take(10)).
      count { |c1, c2| c1 != c2 }
  end

  def self.half_lazy_args(s1, s2)
    s1.each_char.take(10).
      zip(s2.each_char.take(10)).

JoelQ

Decoder Challenge

1. SelectList
2. Currencies with phantom types

JoelQ

-- Maybe

map2 f v1 v2 = Just f |> andMap v1 |> andMap v2
map  f v1    = Just f |> andMap v1
map0 f       = Just f

-- List

map2 f v1 v2 = singleton f |> andMap v1 |> andMap v2
map  f v1    = singleton f |> andMap v1

JoelQ

-- GIVEN

type MyList a
  = Cons a (MyList a)
  | Empty
  

add : Int -> Int -> Int
add a b =
  a + b

JoelQ

A Darwinian Nightmare

It seemed to have stepped right out of the pages of a horror novel. The mutant shape-shifter struck without warning, defying a mere mortal's attempts to detect it. It seemed to distort the fabric of reality itself. And it was going to ruin my job interview.

We've all encountered this monster at some point. Like many classic monsters, it is our own creation. Every year it devastate projects worldwide. The fearsome mutation bug is an expert at hiding and altering your programs in subtle and