Medium Post: Why is a pure FP GraphQL implementation so hard to build?

ResolverExample.purs

postType :: GraphQL.ObjectType Context (Maybe Post)
postType =
  GraphQL.objectType
    "Post"
    (Just "A blog post that is persisted in the database.")
    { comments:
        GraphQL.field
          (GraphQL.nonNull $ GraphQL.list $ GraphQL.nonNull GraphQL.string)
          (Just "The title of this blog post.")
          { max:
            GraphQL.argument
              GraphQL.id
              (Just "The unique id that references this post.")
          }
          ?resolver -- resolver :: Post -> { max: Maybe Int } -> Context -> Aff (Array Comment)
    }