It just dawned on me that the fanciful nonsense I wrote here ages ago
http://blog.sigfpe.com/2006/09/infinitesimal-types.html
makes some kind of sense now that Haskell has linear types
@dpiponi Pondering "so what's a type of which only a single value can exist at a time?", thought of: State# RealWorld. Hmm.
@dpiponi That's my recollection as well
@glaebhoerl I think Clean may do something along these lines https://clean.cs.ru.nl/Clean (It's many years since I last looked at clean.)