[dagw]

You're missing the point. What makes python 'fast' is that it comes with 'out of the box' support for everything I might need. Reading and writing obscure file formats. Every sparse matrix, image processing and graph algorithm I might need has already been implemented. Do I need to all of sudden solve an optimization problem or a differential equation? Already nicely integrated with the library using. If I need some obscure domain specific algorithm, there is almost certainly a library for that already. I don't have to worry about any of that stuff and can focus on solving my problem.

[jhgb]

There's quite a few C/C++ libraries for those things, right? Integrating them with proper FFI (of the kind that Chez has, for example - or LuaJIT, for that matter) seems hardly difficult...although differential equations or optimization problems may be better served without any language interfaces whatsoever since they involve functional parameterization. That generally sucks with mixed-language solutions, to the extent that GSLShell, the LuaJIT interface to GSL, completely skipped the DE solvers in GSL and reimplemented them in Lua for higher performance. I imagine that 'fast' in case of Python really needs to be quoted the way you did.

[kbutler]

"seems hardly difficult" and "could probably use" is seldom faster than "out of the box" and "already nicely integrated"

[jhgb]

Maybe, but the latter definitely isn't the case with Python, especially in case of PyPy (or at least it wasn't the case the last time I tried that), so there's that.