Re: [Haskell-cafe] The Haskell type inference feature I'd really like to see

24 Oct 2008


      On Fri, Oct 24, 2008 at 01:38:23PM -0700, Dan Piponi wrote:
...
I'd like to be able to write something like
...
map zipWith ([1,2,3] >>= printMyInferredType)
and have the compiler treat 'printMyInferredType' as undefined, but
also produce the side effect of printing out its inferred type.
What's the easiest way to simulate this with what we have now?
This will work as long as your type has a typeable instance. You can
modify it to work in an non-io context with unsafePerformIO (as long as
you are aware of the caveats of doing so)


import Data.Typeable

printInferedType :: Typeable a => a -> IO ()
printInferedType x = print (typeOf x)


main = do
    printInferedType ()
    printInferedType "foo"    

-- 
John Meacham - ⑆repetae.net⑆john⑈