Shuffling tables and iterating them in a random order

shuffle.lua

--[[
What if you want to pick a random option but you're not sure if that random option will be valid?
Instead of doing a while loop and hoping that you'll eventually land on a valid option
try shuffling the list of options and trying each one in this random order ;)

W.
--]]

local shuffle = function(table) -- standard Fisher-Yates implementation
  for i = #table, 2, -1 do
    local j = math.random(1, i)
    local swap = table[i]
    table[i] = table[j]
    table[j] = swap
  end
  return t
end

local random_iter = function(table, func)
  local indices = {}
  for i = 1, #table do
    indices[i] = i
  end
  shuffle(indices)
  for i = 1, #indices do
    func(table[indices[i]])
  end
end

return { shuffle = shuffle, random_iter = random_iter }

use_case.lua

local shuffle = require("shuffle")

local is_valid = function(option)
  return not option.used
end

local all_options = { { "foo" }, { "bar" }, { "foobar"} }
.
local do_stuff = function(option)
  print(option[1])
  option.used = true
end

local finished = false
shuffle.random_iter(all_options, function(option)
  if finished or (not is_valid(option)) then 
    return 
  end
  do_stuff(option)
  finished = true
end)