CODEWITHSUNDEEP
haskell
user3373360
user3373360

Reputation: 93

Identity with 2 Functions and Restrictions Haskell

I have this homework question that I don't understand. I'm not sure where to start or what the purpose of this question is as to what it's suppose to do. If anyone could help that'd be great as I am new to Haskell. Below is the question:

identity x = x.  Your definition must have the form identity = e
where e mentions *only* ap and proj and parentheses.
ap f g x = f x (g x)
proj x y = x
identity :: a -> a
identity =

What is this above identity function suppose to accomplish or do after it's given an input?

thanks!

Upvotes: 2

Views: 101

Answers (2)

jakubdaniel
jakubdaniel

Reputation: 2223

One way is identity = (ap proj proj). That makes identity x = proj x (proj x) here (proj x) is a function but that does not matter as it is thrown away, giving you the equality identity x = proj x _ = x.

Upvotes: 0

Daniel Wagner
Daniel Wagner

Reputation: 153132

The identity function returns its input unchanged, as given by the homework question's specification that identity x = x.

Upvotes: 4

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