A gap of about 2x on a benchmark set doesn’t say much, if anything. That’s well within the usual variance you’ll get for any single language from different compilers and from different levels of programmer skill and effort put into manual optimizations. Certainly, much more work has gone into C compilers than Haskell compilers, so one would expect that there’s much more low-hanging fruit for improvement in the latter.
That said, the really interesting figures would be those for nice idiomatic Haskell, as well as figures about what percentage of code must be written using ugly hacks to achieve performance comparable to C. The power of C lies in the fact that you can write nice, manageable, and natural-looking code while having a very good idea about the machine code that comes out of each statement you write. (In fact, C was originally meant to be used with machine code directly in mind, with no need for compiler optimization, though modern architectures are too complicated for that.) Now, in almost any language, you can force a similar approach by using ugly and unnatural hacks based on the intimate knowledge of what your compiler will produce in response. However, that defeats the purpose of using a language more fancy than C, except perhaps if you can justify it by demonstrating that such ugly hacks are necessary only for a minuscule performance-critical part of the code.
A gap of about 2x on a benchmark set doesn’t say much, if anything. That’s well within the usual variance you’ll get for any single language from different compilers and from different levels of programmer skill and effort put into manual optimizations. Certainly, much more work has gone into C compilers than Haskell compilers, so one would expect that there’s much more low-hanging fruit for improvement in the latter.
That said, the really interesting figures would be those for nice idiomatic Haskell, as well as figures about what percentage of code must be written using ugly hacks to achieve performance comparable to C. The power of C lies in the fact that you can write nice, manageable, and natural-looking code while having a very good idea about the machine code that comes out of each statement you write. (In fact, C was originally meant to be used with machine code directly in mind, with no need for compiler optimization, though modern architectures are too complicated for that.) Now, in almost any language, you can force a similar approach by using ugly and unnatural hacks based on the intimate knowledge of what your compiler will produce in response. However, that defeats the purpose of using a language more fancy than C, except perhaps if you can justify it by demonstrating that such ugly hacks are necessary only for a minuscule performance-critical part of the code.
I would like to see that as well, for the reasons you mention.
It would be truly really interesting if any language managed to abstract out the process of optimization significantly more than other languages.