On Thu, Aug 08, 2013 at 05:44:11PM +0100, Tom Ellis wrote: > On Thu, Aug 08, 2013 at 06:25:12PM +0200, Daniel Trstenjak wrote: > > > See [1] for an explanation of free monads in general. For IO in > > > particular, > > > define a functor > > > > > > data IOF a = GetChar (Char -> a) | PutChar Char a | ... > > > > > > with constructors for all elementary IO operations. > > > > But how should this work if the user adds an IO operation, e.g by wrapping > > a C function? > > Wrapping a C function could perhaps be provided by something like > > data IOF a = ... | forall i o. Foreign String i (o -> a) | ... > > csin :: Double -> IO Double > csin x = liftF (Foreign "math.h sin" x id)
I suppose that should actually be 'csin :: CDouble -> IO CDouble', but hopefully the general method is clear. Tom _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
