Can I define a type synonym inside the "let" block?-CodePudding

I want to get something like this. It's possible?

something :: String
something = 
  let
    type FirstName = String
    type LastName = String
    
    fullName :: FirstName -> LastName -> String
    fullName = a    " "    b
  in
    fullName "Haskell" "Curry"

I've been trying to find language extensions that do this, but to no avail.

CodePudding user response：

Direct answer is no, type definitions are possible only on module level.

Something similar is possible:

let
  fullName ::
    (firstName ~ String, lastName ~ String) =>
    firstName -> lastName -> String
  fullName a b = a    " "    b
in
  _