Reduce in Lua

In Lua, you can reduce an array to a single value by using the table.reduce() function. This function takes two arguments: the array to be reduced and a function that specifies how to perform the reduction.

Here's an example that reduces an array of numbers to their sum:

local function sum(a, b)
  return a + b
end
local arr = {1, 2, 3, 4, 5}
local total = table.reduce(arr, sum)
print(total) -- Output: 15

In this example, the sum function takes two arguments and returns their sum. The table.reduce() function applies this function to the elements of the arr array sequentially, starting with the first two elements (1 and 2) and then adding the result to the next element (3), and so on until the entire array has been reduced to a single value.

You can use the table.reduce() function to perform other types of reductions as well. For example, here's how you can find the maximum element in an array:

local function max(a, b)
  if a > b then
    return a
  else
    return b
  end
end
local arr = {1, 9, 2, 5, 7}
local max_value = table.reduce(arr, max)
print(max_value) -- Output: 9

In this example, the max function takes two arguments and returns the larger of the two. The table.reduce() function applies this function to the elements of the arr array sequentially, comparing each element to the previous maximum value and returning the greater of the two. At the end of the reduction, the maximum value in the array is returned.