Haskell does use green threads. The thing is, Haskell code is managed by a Haskell runtime, and each runtime manages a single (processor) thread. So the usual p

Haskell does use green threads. The thing is, Haskell code is managed by a Haskell runtime, and each runtime manages a single (processor) thread. So the usual parallelism model for Haskell is to spawn a runtime for each processor core and then let each runtime manage its own green threads.