Lua code

Lua runs as Lua 5.4 compiled to WebAssembly. It is the lightest of the seven languages: ideal for a short transformation.

The API

Symbol	Role
input	The value received on the input port
vars	A table of the run variables
print(...)	Writes to the execution log (arguments joined by tabs)
return	The value returned leaves on the result port

Example

local commandes = input.commandes
local total, nombre = 0, 0

for _, commande in ipairs(commandes) do
  if commande.statut == "payee" then
    total = total + commande.montant
    nombre = nombre + 1
  end
end

print(string.format("%d commandes payées, total %.2f €", nombre, total))

return { nombre = nombre, total = total }

Things worth knowing

• Lua tables are indexed from 1: input[1] is the first element of a list you receive.
• A table with consecutive numeric keys comes back out as a JSON array; a table with textual keys comes out as an object.
• The standard library is available: string, table, math, os.

External packages

The packages field accepts pure-Lua source LuaRocks modules. They are resolved on the first run then injected offline afterwards.