CODEWITHSUNDEEP
haskell
RandomB
RandomB

Reputation: 3749

What is the reason of error "Not a data constructor"?

I have got an error: Not a data constructor: "%:":

data KV = forall a. Show a => (%:) Text a

Interestingly, but :% is fine as data constructor! %% is not fine again. But %% is fine to be infix function. Why is it treating as an error? What is the difference between these variants?

Upvotes: 2

Views: 282

Answers (1)

Carl
Carl

Reputation: 27023

It's not a valid name for a data constructor. All infix operator data constructors must start with :. So (:%) would be fine.

This is just the operator equivalent of "constructors must start with capital letters", as a syntactic means to distinguish constructors from other names when pattern matching.

Upvotes: 4

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