singletons stuff in GHC.Generics?

Ben Gamari ben at
Wed Mar 30 19:46:22 UTC 2016

Carter Schonwald <carter.schonwald at> writes:

> Hey All, i just noticed that theres some Singletons code in the
> GHC.Generics module thats defined but not exported, whats the context on
> that?
It's used strictly internally in instances defined in GHC.Generics. For

    instance (KnownSymbol n, SingI f, SingI r)
        => Constructor ('MetaCons n f r) where
      conName     _ = symbolVal (Proxy :: Proxy n)
      conFixity   _ = fromSing  (sing  :: Sing f)
      conIsRecord _ = fromSing  (sing  :: Sing r)


- Ben
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