On Tue, Apr 13, 2010 at 05:39:04AM -0700, Hein Hundal wrote:
Thanks Allan!
I was hoping the C-Haskell mix would work. I am glad to hear that you have good things to say about it.
My main reason for thinking about the C-to-Haskell compiler was to address the question "Say you had a C program. Can you always convert it to Haskell in such a way that the compiled Haskell is not too slow and does not need too much memory?" Supposing that too slow means slower than 1/4 the speed of C and too much memory means twice the memory of C.
Do you know the answer to this question?
My guess is that the answer is technically "no". If I recall correctly, there are some imperative data structures where the best known time complexity for a functional version is worse than the imperative version by a factor of (log n), so in that case you wouldn't be able to stay within a constant factor of C. However, I think in practice the answer is usually "yes"; but it might be hard to do it via a mechanical compilation. Idiomatic (and fast) Haskell is often organized very differently than corresponding C code. So if you want to know whether you will necessarily be taking a big performance hit in moving from C to Haskell, the answer is usually no, if the translation is sufficiently intelligent --- which a straightforward C-to-Haskell compiler is (probably) not. -Brent