This ticket might be relevant https://ghc.haskell.org/trac/ghc/ticket/11046
2015-12-10 20:51 GMT+05:00 John Leo <l...@halfaya.org>: > I sent this to haskell-cafe a little while ago but didn't get a response, > so I thought I'd try here. I'd guess this is a case of the GHC user guide > needing an update, but I'd like an expert opinion. > > --- > > According to sections 7.4.3 and 7.4.4 of the latest GHC documentation > > https://downloads.haskell.org/~ghc/latest/docs/html/users_guide/data-type-extensions.html > you can define (7.4.3) an infix type constructor as long as it begins with > a colon, for example > data a :*: b = Foo a b > > and furthermore (7.4.4) you can define an infix operator without having to > use a colon if you enable the TypeOperators extension: > data a * b = Foo a b > > However if I try the former without using TypeOperators I get this > compiler error in 7.10.2: > Illegal declaration of a type or class operator ‘:*:’ > Use TypeOperators to declare operators in type and declarations > > Using TypeOperators fixes this, but then * without colon also works so I > don't see the point of using colon anymore. > > My guess is this was some some kind of historical distinction which is no > longer valid and the documentation needs to be updated. Is this true, or > am I missing something? > > John > > _______________________________________________ > ghc-devs mailing list > ghc-devs@haskell.org > http://mail.haskell.org/cgi-bin/mailman/listinfo/ghc-devs > >
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