operator: sort-by

    description:
        sort-by[op] sp
        natural sort the given superposition with respect to the given operator
        chomps any ',' chars, so you can sort by to-comma-numbers.

    examples:
        load pretty-print-table-of-australian-cities.sw
      
        -- sort by area:
        table[city, area, population, annual-rainfall] sort-by[area] "" |city list>
            +-----------+------+------------+-----------------+
            | city      | area | population | annual-rainfall |
            +-----------+------+------------+-----------------+
            | Darwin    | 112  | 120900     | 1714.7          |
            | Adelaide  | 1295 | 1158259    | 600.5           |
            | Hobart    | 1357 | 205556     | 619.5           |
            | Melbourne | 1566 | 3806092    | 646.9           |
            | Sydney    | 2058 | 4336374    | 1214.8          |
            | Perth     | 5386 | 1554769    | 869.4           |
            | Brisbane  | 5905 | 1857594    | 1146.4          |
            +-----------+------+------------+-----------------+
      
        -- reverse sort by population:
        table[city, area, population, annual-rainfall] reverse sort-by[population] "" |city list>
            +-----------+------+------------+-----------------+
            | city      | area | population | annual-rainfall |
            +-----------+------+------------+-----------------+
            | Sydney    | 2058 | 4336374    | 1214.8          |
            | Melbourne | 1566 | 3806092    | 646.9           |
            | Brisbane  | 5905 | 1857594    | 1146.4          |
            | Perth     | 5386 | 1554769    | 869.4           |
            | Adelaide  | 1295 | 1158259    | 600.5           |
            | Hobart    | 1357 | 205556     | 619.5           |
            | Darwin    | 112  | 120900     | 1714.7          |
            +-----------+------+------------+-----------------+

    see also:
        reverse, table