Haskell to Javascript Lamba function translation

Question

I have the following lambda function in haskell:

cup size = \\message -> message size

I would like to know what is the equivalent version in JavaScript (for learning purpose), currently I wrote the following version, I would like to if it is correct.

const cup = size => (message => message)(size)

Answer 1

Your JavaScript code corresponds to

cup = \size -> (\message -> message) size

in Haskell. Because \\message -> message is the identity function, this is the same as

cup = \size -> size

which is the identity function again:

cup = id

The correct translation would be

const cup = size => message => message(size)

or

function cup(size) { return message => message(size); }

Answer 2

Your haskell lambda takes an argument and returns a lambda which in turn takes a function as argument and applies that function with the argument given to cup.

In javascript, the equivalent would be this:

const cup = size => (message => message(size))

You can rewrite it without the parenthesis:

const cup = size => message => message(size)