List (nub, foldl1') class GShow a where gshow :: a -> String gshowsPrec :: Int a ++ unrollApps ts unrollApps (other:ts) = other : unrollApps ts unrollApp :: Type 

Such a check may be necessary in many cases. For example, it can be used for building a polymorphic function, the one that treats arguments differently depending on their type. The instanceof operator. The syntax is: We can then run yarn build or npm run build to generate a types.d.ts file, see the following output (this is what it looks like when your type annotations have changed or types.d.ts does not exist). We can also look at the contents of the types.d.ts file which contains a function declaration for our ping function and the function signature is: no parameters and a Promise return value.