#10365: Implement Semigroup as a superclass of Monoid Proposal (Phase 1) -------------------------------------+------------------------------------- Reporter: gidyn | Owner: quchen Type: feature request | Status: patch Priority: high | Milestone: 8.0.1 Component: libraries/base | Version: 7.10.1 Resolution: | Keywords: report-impact Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Phab:D1284 Wiki Page: | -------------------------------------+------------------------------------- Comment (by nomeata): I follow ekmett’s argument that Monoid to [] is like semigroups to ?, and to me it makes sense of have a type for non-empty sets in base. (If having a slim base were a goal, then maybe not, but I don’t see that being a goal for the community in general). But it is true that things are harder to fix once they are in base, so we should aim to pick the “right” implementation. According to https://wiki.haskell.org/Non-empty_list#Packages there are 6(!) implementations of non-empty lists on hackage. I did not look at them right now, so I’ll lazily pose the question: Is there any good reason to prefer any of these over the implementation from `semigroups`? -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/10365#comment:36 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler