On 20 May 2010 21:16, Evan Laforge <qdun...@gmail.com> wrote: > Someone recently described the HASP project, at > http://hasp.cs.pdx.edu/. It describes "habit", a haskell like > language with some additions and subtractions. There are a couple > interesting extensions to 'instance' declarations: > > -- explicitly declare that there is no instance, halting the compiler's search > instance xyz fails > > -- declares instances along with search order > instance abc ... > else def > > The result is that if you put 'fails' at the end, you can make a > closed typeclass. Presumably you could also make typeclasses open but > only in a restricted way. Also presumably the compiler would then be > able to make better decisions about overlapping instances and you > could avoid a lot of overlapping problems. > > Of course, it's just a paper with no compiler, so it's all > "presumably" for the moment...
Hi Evan, hasn't EHC had something like this for a while with 'type class directives'? _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe