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"Dynamic Typing in Polymorphic Languages"
Martin Abadi, Luca Cardelli, Benjamin Pierce, Didier Remy
January 26, 1994.  22 pages.

There are situations in programming where some dynamic typing
is needed, even in the presence of advanced static type systems.
We investigate the interplay of dynamic types with other advanced type
constructions, discussing their integration into languages with
explicit polymorphism (in the style of system F), implicit polymorphism 
(in the style of ML), abstract data types, and subtyping.