mapM as a Space Leak (Was: [Haskell-cafe] about Haskell code written to be "too smart")

[Jonathan Cast]

On Thu, 2009-03-26 at 12:29 -0700, Thomas Hartman wrote:
> > I wonder if JHC
> > or some other compiler might work better with these examples?
> 
> Are you saying that different compilers might give different answers?
> 
> Yikes!
> 
> Too clever indeed!

No, they might produce code with different performance characteristics.

Which is very much what you want; there is no way to compile Haskell
such that reasonable-looking code is

 a) Fast and
 b) Predictably performant.

The idea of Haskell is to abstract away from the predictable performance
of the code by a) using a good compiler, and b) putting absolute
un-questioning faith in your profiler.

jcc