On 08/03/10 15:23, John Meacham wrote:
It is more an accident of ghc's design than anything, the same mechanism that allowed threads to call back into the runtime also allowed them to be non blocking so the previously used 'safe' and 'unsafe' terms got re-used. personally, I really don't like those terms, they are non-descriptive in terms of what they actually mean and presuppose a RTS similar to ghcs current design. 'reentrant' and 'blocking' which could be specified independently would be better and would be more future-proof against changes in the RTS or between compilers.
John
Okay, that makes a lot more sense. So really when marking a call "safe" or "unsafe" I shouldn't be thinking in terms of whether I want to avoid the increased overhead of allowing it to call back into Haskell, but rather I should be considering whether I want to call to block other threads or not. However, it would seem that within this scheme there is no way for me to specify that a foreign call should be both "blocking" and also allowed to call Haskell functions, which to me would be the "safe"est possible alternative. Cheers, Greg