On Fri, Jun 01, 2007 at 07:39:32PM +0100, Andrew Coppin wrote:
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.
Then I'm confused. What typecast are you talking about? -- David Roundy Department of Physics Oregon State University