Equality Constraints (a ~ b)

[Dominic Steinitz]

Hi,

I am trying to find more background on these. They don’t exist in the Haskell 2010 Language Report, they didn’t exist in ghc 6.8.2 but make an appearance in 7.0.1. The documentation in the manual is rather sparse and doesn’t contain a reference: https://downloads.haskell.org/~ghc/latest/docs/users_guide.pdf section 7.11. Folk on #ghc referred me to http://research.microsoft.com/en-us/um/people/simonpj/papers/ext-f/. I can find papers that refer to ~ in F_C (aka FC?) but as far as I can tell not in the Haskell language itself.

Many thanks

Dominic Steinitz
dominic at steinitz.org
http://idontgetoutmuch.wordpress.com