Functor instance won't compile

failingfunctor.purs

module Main where

import Prelude

import Control.Monad.Eff (Eff)
import Data.Foldable (fold)
import TryPureScript (DOM, h1, h2, p, text, list, indent, link, render, code)
import Data.Map (Map, lookup, insert, empty)
import Data.List
import Data.Either
import Data.Maybe

data Tuple a b = Tuple a b
data Primitive = String String | Boolean Boolean | Number Number | Null
data JsonValue = Object (Map String JsonValue) | Array (List JsonValue) | Primitive
data Key = Str String | Range Int Int
data KeySet = SingleKey Key | MultiKey Key
type Path = List String
type PathSet = List KeySet
data JsonGraphValue = JsonGraphObject (Map String JsonGraphValue) | Atom JsonValue | Ref Path | Error JsonValue | JsonPrimitive Primitive

newtype JsonGraphRecResult a = JsonGraphRecResult (Either String (Tuple (Maybe a) (List Path)))
instance jsonGraphRecResultFunctor :: Functor JsonGraphRecResult where
  map f (JsonGraphRecResult (Right (Tuple (Just value) paths))) = JsonGraphRecResult (Right (Tuple (Just (f value)) paths))
  map f value = value

newtype Blah a = Blah (Maybe a)
instance blahFunctor :: Functor Blah where
  map f (Blah (Just x)) = Blah (Just (f x))
  map f value = value