How do I set up a nix-shell script for lua?

Question

I am trying to set up a nix-shell script which contains lua 5.2, the lua sockets library, and a few other libraries. However, when I load the shell, only Lua ends up being present.

with import <nixpkgs> {};
stdenv.mkDerivation rec {
  name = "lua-env";
  buildInputs = [ lua52Packages.lua lua52Packages.luasocket lua52Packages.luasec lua52Packages.cjson ];
}

When I run the shell, this is what I get:

savanni@lapis:~  $ nix-shell lua.nix 

[nix-shell:~]$ lua
Lua 5.2.3  Copyright (C) 1994-2013 Lua.org, PUC-Rio
> require 'socket'
stdin:1: module 'socket' not found:
    no field package.preload['socket']
    no file '/usr/share/lua/5.2/socket.lua'
    no file '/usr/share/lua/5.2/socket/init.lua'
    no file '/usr/lib/lua/5.2/socket.lua'
    no file '/usr/lib/lua/5.2/socket/init.lua'
    no file './socket.lua'
    no file '/usr/lib/lua/5.2/socket.so'
    no file '/usr/lib/lua/5.2/loadall.so'
    no file './socket.so'
stack traceback:
    [C]: in function 'require'
    stdin:1: in main chunk
    [C]: in ?
> 

[nix-shell:~]$ exit
savanni@lapis:~  $

No. I probably could, now, but I no longer work somewhere that lua is a thing and so haven't even tried. Would you like me to? — Savanni D'Gerinel, Feb 20 '17 at 00:25
It would be helpful. I'm currently stumped with getting [this](https://gist.github.com/Unode/780ea94c2415097cc3d8da5dc4276e1b) to work. — Unode, Mar 16 '17 at 10:43

wizzup · Accepted Answer · 2017-08-24T13:41:12.900

You have to set LUA_PATH and LUA_CPATH

This shell.nix should work,

with import <nixpkgs> {};
with luaPackages;

let
  libs = [lua cjson luasocket luasec];
in
stdenv.mkDerivation rec {
  name = "lua-env";
  buildInputs = libs;

  shellHook = ''
    export LUA_CPATH="${lib.concatStringsSep ";" (map getLuaCPath libs)}"
    export LUA_PATH="${lib.concatStringsSep ";" (map getLuaPath libs)}"
  '';
}

To check that those paths are exported,

$ nix-shell --run 'echo $LUA_CPATH; echo $LUA_PATH'
/nix/store/lp0ns0hjwx1klk6amnyic3f62bw7h8j7-lua-5.2.3/lib/lua/5.2/?.so;/nix/store/lp0ns0hjwx1klk6amnyic3f62bw7h8j7-lua-5.2.3/share/lua/5.2/?.so;/nix/store/ppdspfcm5nnfz0fk9zarjmpyv5lcmn18-lua5.2-cjson-2.1.0/lib/lua/5.2/?.so;/nix/store/ppdspfcm5nnfz0fk9zarjmpyv5lcmn18-lua5.2-cjson-2.1.0/share/lua/5.2/?.so;/nix/store/b71xyq7gkc8iccj6wr84zq31gqc3m9ix-lua5.2-socket-3.0-rc1/lib/lua/5.2/?.so;/nix/store/b71xyq7gkc8iccj6wr84zq31gqc3m9ix-lua5.2-socket-3.0-rc1/share/lua/5.2/?.so;/nix/store/6q8xn2bcfskmrfzql47jld5d2irvn5jr-lua5.2-sec-0.6/lib/lua/5.2/?.so;/nix/store/6q8xn2bcfskmrfzql47jld5d2irvn5jr-lua5.2-sec-0.6/share/lua/5.2/?.so
/nix/store/lp0ns0hjwx1klk6amnyic3f62bw7h8j7-lua-5.2.3/lib/lua/5.2/?.lua;/nix/store/lp0ns0hjwx1klk6amnyic3f62bw7h8j7-lua-5.2.3/share/lua/5.2/?.lua;/nix/store/ppdspfcm5nnfz0fk9zarjmpyv5lcmn18-lua5.2-cjson-2.1.0/lib/lua/5.2/?.lua;/nix/store/ppdspfcm5nnfz0fk9zarjmpyv5lcmn18-lua5.2-cjson-2.1.0/share/lua/5.2/?.lua;/nix/store/b71xyq7gkc8iccj6wr84zq31gqc3m9ix-lua5.2-socket-3.0-rc1/lib/lua/5.2/?.lua;/nix/store/b71xyq7gkc8iccj6wr84zq31gqc3m9ix-lua5.2-socket-3.0-rc1/share/lua/5.2/?.lua;/nix/store/6q8xn2bcfskmrfzql47jld5d2irvn5jr-lua5.2-sec-0.6/lib/lua/5.2/?.lua;/nix/store/6q8xn2bcfskmrfzql47jld5d2irvn5jr-lua5.2-sec-0.6/share/lua/5.2/?.lua

Apologies for the extremely long delay. This had stopped being relevant to me, and I clearly missed the notification until today. I just tried out the shell.nix that you wrote and it worked perfectly in an instant, though today I think we would use `mkShell` instead of `mkDerivation`. — Savanni D'Gerinel, Jan 09 '20 at 20:24

Lucas · Answer 2 · 2021-07-01T10:58:11.233

0

There is a simpler way to do this in 2020:

nix-shell -p 'lua.withPackages(ps: [ps.luasocket ps.cjson])'

This will put a modified lua derivation in your environment where the luasocket and cjson derivations from luaPackages are included in the LUA_PATH.

So you do not need to mess with LUA_PATH or shellHooks yourself.

EDIT:

You can use the lua.withPackages function in a nix file as well:

with import <nixpkgs> {};
stdenv.mkDerivation rec {
  name = "lua-env";
  buildInputs = [ lua.withPackages(ps: with ps; [luasocket luasec cjson ]) ];
}

edited Jul 01 '21 at 10:58

answered Dec 13 '20 at 13:51

Lucas

173
8

These `nix-shell` commands, whilst short, really don't help the whole "declarative" and commitable nature of .nix files. – Rebs Mar 02 '21 at 10:41
1

@Rebs I updated the answer on how to use this function declarative – Lucas Jul 01 '21 at 10:58

How do I set up a nix-shell script for lua?

2 Answers2