-- @shouldFailWith NoInstanceFound module Main where import Prim.TypeError (class Fail, Text) class C x where thing :: x -> x data X a b = X test1 :: forall a. X a Int test1 = X instance cx :: C (X x x) where thing x = x else instance cxFail :: Fail (Text "Fell through") => C (X x y) where thing x = x test2 :: Boolean test2 = do let X = thing test1 true