Programming Elm

Get Lazy

If you’ve ever wanted a reward for laziness, this section is for you. You will discover eager and lazy evaluation and how each impacts performance. You will use elm-benchmark and lazy design patterns to dramatically improve the performance of a function. Along the way, you will learn about thunks and the Dict type.

As you continue examining Rescue Me’s codebase, you encounter a new feature to track dogs that know tricks. Rescue Me represents dogs with a record type and tricks with a custom type.

fast/fast-code/GetDog01.elm

type Trick
    = Sit
    | RollOver
    | Speak
    | Fetch
    | Spin


type alias Dog =
    { name : String
    , tricks : List Trick
    }

You find a getDog function that looks questionable.

getDog ...