Re: 'import ccall unsafe' and parallelism

I'm no judge of what's true about safe and unsafe, but this account of the system has at least to my ear the ring of authenticity: http://blog.melding-monads.com/2011/10/24/concurrency-and-foreign-functions-... The FFI section is short and readable. With respect to whether "unsafe" does or does not block other threads, I can never penetrate the verbiage about capabilities to know for sure what to expect in practice, but when I checked, in practice, "unsafe" blocks other threads. I use "safe" to avoid this. Donn