Question

Given the following type of expressions data Expr a = Var a | Val Int | Add (Expr a) (Expr a) deriving Show data Expr a = Var a $\mid$ Val Int $\mid$ Add (Expr a) (Expr a) deriving show that contain variables of some type a, show how to make this type into instances of the Functor, Applicative and Monad classes. With the aid of an example, explain what the $\gg>=$ operator for this type does.

   Given the following type of expressions
data Expr a = Var a | Val Int | Add
(Expr a) (Expr a)
deriving Show
data Expr a = Var a $\mid$ Val Int $\mid$ Add
(Expr a) (Expr a)
deriving show
that contain variables of some type a, show how to make this type into instances of the Functor, Applicative and Monad classes. With the aid of an example, explain what the $\gg>=$ operator for this type does.

Show more…

Programming in Haskell

Programming in Haskell

Graham Hutton 2nd Edition

Chapter 12, Problem 7

Instant Answer

Step 1

The fmap function takes a function f and an Expr a value, and applies the function f to the value inside the Expr a. instance Functor Expr where fmap f (Var a) = Var (f a) fmap _ (Val x) = Val x fmap f (Add expr1 expr2) = Add (fmap f expr1) (fmap f Show more…

Show all steps

lock

Thanks for your feedback!

Given the following type of expressions data Expr a = Var a | Val Int | Add (Expr a) (Expr a) deriving Show data Expr a = Var a $\mid$ Val Int $\mid$ Add (Expr a) (Expr a) deriving show that contain variables of some type a, show how to make this type into instances of the Functor, Applicative and Monad classes. With the aid of an example, explain what the $\gg>=$ operator for this type does.

Play audio

Feedback

Powered by NumerAI

Ace is your personal tutor. It breaks down any question with clear steps so you can learn.

Start Using Ace

Continue solving this problem

Create a free account to:

View full step-by-step solution
Ask follow-up questions with Ace AI
Save progress and study later