I have OS X Yosemite 10.10.4. There are two bundles of GHC (from ghcformacosx.github.io): 7.10.1 and 7.10.2. The latter always shows me one core when running `getNumCapabilities` action: *GHC 7.10.2*
stack ghci +RTS -N8 Using resolver: lts-3.0 from global config file: /Users/arthurfayzrakhmanov/.stack/global/stack.yaml Configuring GHCi with the following packages: GHCi, version 7.10.2: http://www.haskell.org/ghc/ :? for help Prelude> :m +Control.Concurrent Prelude Control.Concurrent> getNumCapabilities 1
*GHC 7.10.1*
/Applications/ghc-7.10.1.app/Contents/bin/ghci +RTS -N8 GHCi, version 7.10.1: http://www.haskell.org/ghc/ :? for help Prelude> :m +Control.Concurrent Prelude Control.Concurrent> getNumCapabilities 8
It looks like a 7.10.2 bug, can some one confirm that?