OO as structurally typed polymorphic records in Elm

oo.elm

type Named a = { a | name: String }
type Greeter a = { a | greet: (String -> String) }

bob   = { name = "Bob",   age = 12 }
alice = { name = "Alice", age = 19, gender = "F" }

makeGreeterFromString: String -> Greeter {}
makeGreeterFromString name  = { greet = \how -> how ++ ", " ++ name }

makeGreeterFromNamed: Named a -> Greeter (Named a)
makeGreeterFromNamed person = { person | greet = \how -> how ++ " " ++ person.name }


g'  = makeGreeterFromString bob.name
g'' = makeGreeterFromNamed alice


main = flow down <| map asText [ g'.greet "Hello"
                               , g''.greet "Hi"
                               ]