3 ms·

I think Lua's biggest assets are how easily it can be used with C (which is where a lot of the speed comes from), and how incredibly portable it is. The languag

I think Lua's biggest assets are how easily it can be used with C (which is where a lot of the speed comes from), and how incredibly portable it is. The language is freaking tiny, it will run on anything with a C compiler, and it usually builds in just a few seconds. While it doesn't have a huge standard library, there are tons of C libraries, and writing Lua wrappers for them is dead easy. Also, LPEG (http://www.inf.puc-rio.br/~roberto/lpeg/lpeg.html http://www.inf.puc-rio.br/~roberto/lpeg/lpeg.html) rules. Edit: That's what I meant, that you can move code over to C. That Lua itself is faster than the other major scripting languages is just a nice perk. :) (Also, there's LuaJIT, but only on i386.)

davidw 17y ago
> easily it can be used with C (which is where a lot of the speed comes from) I don't think the two are necessarily related: Tcl has a great C API, but is middle of the pack in terms of its own speed. Of course a good C API is an essential 'out' for scripting languages, so that you can write stuff in C where needed. Indeed, the idea behind Tcl was to not care much about Tcl's speed, because performance critical stuff would be done in C anyway.
jnoller 17y ago
Python has a good CAPI too
- silentbicycle 17y ago
  Well, all the Lua state is contained in one Lua_state pointer, so you can run several concurrent Lua VMs without the sort of problems caused by Python's global interpreter lock. (Speaking of which, there's also ConcurrentLua (http://concurrentlua.luaforge.net/ http://concurrentlua.luaforge.net/), which adds Erlang-style message-passing concurrency.)
limmeau 17y ago
AFAIK, Lua has only one numeric data type, double-precision floating-point numbers. That kind of scares me -- I like my integers integer and not approximated. Does that, in your experience, cause problems in practice? (Yes, I know that in principle, IEEE 754 Doubles can represent all 52-bit integers precisely (give or take a few bits), but still I don't feel comfortable).
- silentbicycle 17y ago
  It hasn't been a problem for me. There are a couple arbitrary precision libraries for Lua, so I just use those when it would matter. I've used: * lbc: http://www.tecgraf.puc-rio.br/~lhf/ftp/lua/#lbc * GMP wrapper: http://members.chello.nl/~w.couwenberg/ and there are more linked here, under "Math": http://lua-users.org/wiki/LibrariesAndBindings http://lua-users.org/wiki/LibrariesAndBindings Lua uses doubles by default, but you can change the numeric type quite easily via luaconf.h (http://www.lua.org/manual/5.1/manual.html#lua_Number http://www.lua.org/manual/5.1/manual.html#lua_Number), if you need to work on a platform for which doubles are too large, if you'd prefer to use 64-bit longs, etc. Lua is designed to be small enough that you can just include the whole language in your source tree as a library, if you need a custom version. Think of it as a 200k .dll/.so that gives your C program a scripting interface / config file parser, a generational garbage collector (for the Lua portion), and a great string and hash table library. (The standalone Lua interpreter is just a thin wrapper to add a REPL to the C API.) Lua code also works well as a data serialization format; it's very similar to JSON, and the Lua compiler has been tuned specifically for rapidly compiling data dumped as Lua literals.
  - limmeau 17y ago
    Thanks! I'll try that sometime.

davidw 17y ago

> easily it can be used with C (which is where a lot of the speed comes from) I don't think the two are necessarily related: Tcl has a great C API, but is middle of the pack in terms of its own speed. Of course a good C API is an essential 'out' for scripting languages, so that you can write stuff in C where needed. Indeed, the idea behind Tcl was to not care much about Tcl's speed, because performance critical stuff would be done in C anyway.

jnoller 17y ago

Python has a good CAPI too

silentbicycle 17y ago
Well, all the Lua state is contained in one Lua_state pointer, so you can run several concurrent Lua VMs without the sort of problems caused by Python's global interpreter lock. (Speaking of which, there's also ConcurrentLua (http://concurrentlua.luaforge.net/ http://concurrentlua.luaforge.net/), which adds Erlang-style message-passing concurrency.)

limmeau 17y ago

AFAIK, Lua has only one numeric data type, double-precision floating-point numbers. That kind of scares me -- I like my integers integer and not approximated. Does that, in your experience, cause problems in practice? (Yes, I know that in principle, IEEE 754 Doubles can represent all 52-bit integers precisely (give or take a few bits), but still I don't feel comfortable).

silentbicycle 17y ago
It hasn't been a problem for me. There are a couple arbitrary precision libraries for Lua, so I just use those when it would matter. I've used: * lbc: http://www.tecgraf.puc-rio.br/~lhf/ftp/lua/#lbc * GMP wrapper: http://members.chello.nl/~w.couwenberg/ and there are more linked here, under "Math": http://lua-users.org/wiki/LibrariesAndBindings http://lua-users.org/wiki/LibrariesAndBindings Lua uses doubles by default, but you can change the numeric type quite easily via luaconf.h (http://www.lua.org/manual/5.1/manual.html#lua_Number http://www.lua.org/manual/5.1/manual.html#lua_Number), if you need to work on a platform for which doubles are too large, if you'd prefer to use 64-bit longs, etc. Lua is designed to be small enough that you can just include the whole language in your source tree as a library, if you need a custom version. Think of it as a 200k .dll/.so that gives your C program a scripting interface / config file parser, a generational garbage collector (for the Lua portion), and a great string and hash table library. (The standalone Lua interpreter is just a thin wrapper to add a REPL to the C API.) Lua code also works well as a data serialization format; it's very similar to JSON, and the Lua compiler has been tuned specifically for rapidly compiling data dumped as Lua literals.
- limmeau 17y ago
  Thanks! I'll try that sometime.