David Roundy wrote:
On Fri, Jun 01, 2007 at 07:28:07PM +0100, Andrew Coppin wrote:
David Roundy wrote:
Note also that you can use unsafePerformIO to safely get pure functions
doing both these operations.
I've always been puzzled by this one... how does unsafePerformIO
circumvent the type system? I don't understand.
It's a primitive. You couldn't implement it unless you're the
compiler-writer. But it's a necesary primitive, if you wish to build
efficient data types. You just need to carefully audit everywhere that
unsafePerformIO is used.
No, I mean... how could you use unsafePerformIO to perform a typecast? I
don't see a way to do that.
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