modgud_unsafe.hs

{-# LANGUAGE MagicHash #-}
{-# LANGUAGE UnboxedTuples #-}
{-# LANGUAGE UnliftedFFITypes #-}

module Modgud.Unsafe
  ( threadId
  )
where
import GHC.Exts (ThreadId#, myThreadId#)
import Data.Word (Word64)
import Foreign.C.Types (CULLong(..))
import GHC.IO (IO(..))

foreign import ccall unsafe "rts_getThreadId" getThreadId :: ThreadId# -> CULLong

-- | Convenience version of 'getThreadId' that we can pretty print without roundtripping through Show.
threadId :: IO Word64
threadId = IO $ \s ->
   case myThreadId# s of
     (# s1, tid #) -> case getThreadId tid of
       CULLong ll -> (# s1, ll #)