On Wed, 2009-11-04 at 15:40 +0000, Simon Marlow wrote:
On 16/10/2009 14:22, Martijn van Steenbergen wrote:
Hello,
I propose the addition of the following two functions to module Debug.Trace:
traceM :: Monad m => String -> m () traceM msg = trace msg (return ())
traceShowM :: (Show a, Monad m) => a -> m () traceShowM = traceM . show
is traceShowM really necessary? It doesn't save many characters, and fails the "don't name a composition" test.
As a post-deadline suggestion to fix Simon's (valid) reservation: traceShowM :: (Show a, Monad m) => a -> m a traceShowM a = traceM (show a) a This allows easier trace insertion, e.g.: foo a = do x <- bar a y <- frop x becomes foo a = do x <- bar a >>= traceShowM y <- frop x >>= traceShowM This, to me, looks like a nice syntactic solution. Regards, Philip PS. Is there some seq/deep_seq/strict/whatever solution for the lazy monads problem hiding in here somewhere?