On Thu, 2008-02-14 at 12:00 -0800, John Meacham wrote:
I mildly prefer 'Idempotent' to 'Dupable'. feels more descriptive to me. This is even useful in jhc without threading, as expressions can be marked 'idempotent and cheap' giving the compiler freedom to duplicate them when it makes sense.
It's a fair point. I don't really mind, if other people prefer that name then fine.
However, I am worried about the 'Inline' in the other one, in jhc, unsafePerformIO is always inlined, it uses a different trick (my 'dependingOn' primitive) to ensure the world is not unified with another one.
Can we come up with a term that describes the difference other than 'inline' as that is a ghc specific quirk.
Mm, you're right, it is ghc specific. The semantics are less to do with inlining (though that's the perf advantage) and more about doing dangerous things with the world token. Can anyone suggest a better name?
incidentally, jhc has another form of unsafePerformIO that does not wrap its argument in a new exception handler. It can be used when you know the argument won't raise an ioError or if it does, it handles them itself. (normal calls to things like error and pattern match failures are fine. it is just haskell98 io errors that metter for this one)
Right, GHC misses this once because it doesn't wrap any in an exception handler since its exception mechanism for IO errors is the same as for 'error'. If you have a good name and documentation then propose it now. Duncan