Re: proposal: add 'unsafeCoerce'

Taral writes:

On 11/20/06, Malcolm Wallace wrote:

...

newtype Wrapper a = Wrap a convert :: [a] -> [Wrapper a] convert xs = map Wrap xs

Interesting! Looks like the compiler lacks rules for optimizing "map id" &c.\

And not all compilers have optimisation phases.

Your coercion does assume that the underlying runtime doesn't have some kind of type-tag implementation of type classes.

I believe this is guaranteed by the definition of newtype in the Language Report. Regards, Malcolm