Simon Peyton-Jones wrote:
It used to be, because GHC used to implement so-called "deep skolemisation".
See Section 4.6.2 of
http://research.microsoft.com/en-us/um/people/simonpj/papers/higher-rank/putting.pdf
Deep skolemisation was an unfortunate casualty of the push to add impredicative polymoprhism. However, as I mentioned in an earlier email, I'm currently planning to take impredicative polymorphism *out*, which means that deep skolemisation might come back *in*.
Are there workarounds for uses of impredicative types, or do we lose the
ability to express certain programs as a result?
Thanks,
Martijn.
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