concurrency

Hello all, Haskell implementation can have one of 4 levels of concurrency support: 1) no support at all 2) emulation of concurrency primitives ("blocked" ffi calls, MVar via IORef and so on) 3) cooperative concurrency 4) preemptive concurrency imho, it would be great to prohibit 1) and define requirements to the 2)-4) in the standard -- Best regards, Bulat mailto:Bulat.Ziganshin@gmail.com