Not an array language (AFAIU), but here are some of the mentioned problems solved in (glorious) Factor:

    : find-gcd ( nums -- gcd )
      [ infimum ] [ supremum ] bi gcd nip ;

    : max-wealth ( accounts -- n )
      [ sum ] map-supremum ;

    : which-max-wealth ( accounts -- i )
      [ sum ] supremum-by* drop ;

    primes-upto