
<interactive>:12:1:
    Unacceptable result type in foreign declaration:
      Safe Haskell is on, all FFI imports must be in the IO monad
    When checking declaration:
      foreign import ccall safe "static sin" c_sin :: Double -> Double

<interactive>:13:1:
    Not in scope: ‘c_sin’
    Perhaps you meant ‘c_sin'’ (line 8)