Newtype wrappers

Herbert Valerio Riedel hvr at
Mon Jan 14 19:54:54 CET 2013

Simon Peyton-Jones <simonpj at> writes:


> x1 :: [Int]
> x2 :: Char -> Int
> x3 :: T Int
> x4 :: S IO Int
> Can we convert these into the corresponding forms where the Int is
> replaced by Age? Alas, not easily, and certainly not without overhead

Maybe a stupid question: Can unsafeCoerce accomplish (albeit in an
unsafe way) the desired Int-to-Age type conversion for x1,x2,x3,x4
already now? How does unsafeCoerce relate to the proposal at hand?


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