[TYPES] Has anyone seen a language with sub-typing and recursive parametric type aliases?

[François Pottier]

Hello,

If I am not mistaken, already deciding the *equivalence* of two types
in the presence of recursive and parameterized type abbreviations is
extremely costly: Marvin Solomon proved it equivalent to the DPDA
equivalence problem ("Type definitions with parameters", POPL'78).

-- 
François Pottier
francois.pottier at inria.fr
http://cambium.inria.fr/~fpottier/