Como eu configuro um script nix-shell para lua?

Question

Estou tentando configurar um script nix-shell que contém lua 5.2, a biblioteca de soquetes lua e algumas outras bibliotecas. Porém, quando eu carrego o shell, apenas Lua acaba estando presente.

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

Quando executo o shell, é isso que recebo:

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:~  $ 

    

Answer 1

Você precisa definir LUA_PATH e LUA_CPATH

Este shell.nix deve funcionar,

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)}"
  '';
}

Para verificar se esses caminhos são exportados,

$ 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