On Tue, Oct 13, 2009 at 3:37 AM, Simon Peyton-Jones <simo...@microsoft.com> wrote: [...] > It's also worth noting that while "undecidable" instances sound scary, but > all it means is that the type checker can't prove that type inference will > terminate. We accept this lack-of-guarantee for the programs we *run*, and > type inference can (worst case) take exponential time which is not so > different from failing to terminate; so risking non-termination in type > inference is arguably not so bad. > > Simon
Indeed! On a related note, template instantiation in C++ is undecidable. See ``C++ Templates are Turing Complete'' by Todd Veldhuizen: <http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.14.3670>. And similarly, heavy use of templates in C++ can be *extremely* compute-intensive. Sincerely, Brad _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
