[Haskell-cafe] Portable implementation of unsafeCoerce
john at repetae.net
Thu Feb 8 18:51:07 EST 2007
On Tue, Feb 06, 2007 at 04:58:28PM +0100, Alfonso Acosta wrote:
> Hi all,
> Reading the sources of Lava (a Haskell Hardware Description DSL) I run
> into this definition ...
> unsafeCoerce :: a -> b
> unsafeCoerce a = unsafePerformIO $
> do writeIORef ref a
> readIORef ref
> ref = unsafePerformIO $
> do newIORef undefined
> Is this actually equivalent to the infamous unsafeCoerce# ?
Certainly not in jhc. However, In jhc one can use unsafeCoerce__ which
is provided in Jhc.Prim. An important restriction on using it in jhc
that might not be obvious is that you must not 'seq' a value that has
been coerced to another type.
John Meacham - ⑆repetae.net⑆john⑈
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