Deadline of 2 weeks.

Original discussion: ⁽¹⁾

data Zero a

data One  a = One

Same definitions as in ‘trivia’ package,⁽²⁾
if a consensus is reached we can update
the documentation for Free:⁽³⁾

“Free Zero” is isomorphic to Identity.

“Free One” is isomorphic to Maybe.

⁽¹⁾ https://ghc.haskell.org/trac/ghc/ticket/13177
⁽²⁾ https://hackage.haskell.org/package/trivia
⁽³⁾ https://hackage.haskell.org/package/free-4.12.4/docs/Control-Monad-Free.html