Minimal element of an array

An abstract question, not related to any particular language:

If I have a function as follows

min(int, int) :: int

which returns the smallest value in an array, and

concat([int], [int]) :: [int]

which combines two arrays, how should I write a function like

minInArray([int]) :: Int

which returns the smallest element in an array, but where the ouput could be chained like so, even with an empty input array:

min(minInArray(array1), minInArray(array2)) == minInArray(concat(array1, array2))

In other words, is there any commonly-used neutral element which minInArray could return on empty input, which wouldn't mess up min()?