Re: Add NonEmptyMap and NonEmptySet to containers

I’m not sure what you mean here by “always requires a type synonym” ... example :: NonEmpty X -> Y

Jon, here you are exactly demonstrating the problem. NonEmpty what? List, Set, Map, HashMap, IntMap, ...? On 2019-04-28 00:07, Jon Purdy wrote:

On Thu, Apr 18, 2019 at 11:49 PM Andreas Abel mailto:andreas.abel@ifi.lmu.de> wrote:

We definitely should /not/ repeat the choice made for Data.List.NonEmpty.NonEmpty.  Using non-empty lists /always/ requires a type synonym, like

   import qualified Data.List.NonEmpty as NEList    type NEList = NEList.NonEmpty

which is quite ugly, and type synonyms are sometimes expanded in GHC error messages, which causes additional trouble.

I’m not sure what you mean here by “always requires a type synonym”—I typically use NonEmpty like any other module meant to be imported qualified, like Text, Vector, Map, Set, &c.:

import Data.List.NonEmpty (NonEmpty) import qualified Data.List.NonEmpty as NonEmpty  -- or NE if I’m lazy

example :: NonEmpty X -> Y