Re: Enumerated data types

In article <1990Aug23.134826.2865@forwiss.uni-passau.de> Luis Mandel writes:
>[query about enumerated types with name clashes]


If I remember rightly, Russell has enumerated types. Since constants in
Russell are linguistically 0-ary functions, figuring out whether a given
instance of "red" would in full Russell be bike_colours$red[] or
car_colour$red[] is a particular case of the type inference problem, and
the same kind of context (i.e. how is the result used?) would be used to
decide whether succ[red] is bike_colours$succ[bike_colours$red[]] or ...
well, you get the idea. :-)


The BSD version of Russell had a kind of convoluted but usually workable
heuristic for type inference. Hans Boehm showed that the problem of type
inference is undecidable, but I think he's recently written a paper that
appeared in SIGPLAN Notices that perhaps gives a useful subset of the
problem that's easier to figure out. I hope that a new Russell or language
like it appears that implements such work, because Russell is, IMHO, a
very spiffy language and merits study by any would-be language designer.


James Jones
--

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