Solved how? Most Haskell performance advice (like Tibbel's recent presentation) is to add strictness annotations, which is both non-Haskell98 and non-lazy. So it is solved, but not elegantly or hidden in core libraries.
Fair point. I meant solved in that it's not difficult with a bit of experience and profiling. I actually don't mind the workflow of writing naive (or non-prematurely-optimized) code and then adding strictness hints where the compiler needs it.
