[m-dev.] Re: For review: changes to graph.m
bromage at cs.mu.oz.au
Wed Jun 4 17:27:15 AEST 1997
> > Ignoring the possibility of changing between representations depending
> > on the amount of data stored (eg represent sets by lists for "small"
> > data sets and trees for "big" sets), this is a perfect application of
> > existential types, which are on the "to do" list.
Peter Schachte replied:
> How do existential types help with this?
Having a type class `set(T)' helps in that you have one interface
which can be implemented in many ways. However you need existential
types if, for example, you wanted to create a list of sets.
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