[TYPES] union types and overloading

[Neelakantan Krishnaswami]

Kwangkeun Yi writes:
> 
> I would like to extend our ML compiler's type system so that it
> allow functions to be defined over the sum of multiple
> datatypes. (union types?)
> 
> Could you point me to some papers that I have to check out to avoid
> reinvention or to expect possible obstacles?

Hello,

Barry Jay's paper "The Pattern Calculus" is about exactly what you
describe.

<http://www-staff.it.uts.edu.au/~cbj/Publications/pattern_calculus.ps>

Another approach is to use row polymorphism to type extensible
sums. Ocaml has this feature, and calls it "polymorphic variants". I
think Didier Remy's paper "Records and Variants as a Natural Extension
of ML" introduced the idea.

<http://portal.acm.org/citation.cfm?doid=75277.75284>


-- 
Neel Krishnaswami
neelk at cs.cmu.edu