↑ ABC Example: A Telephone List

This uses the table data-type. In use, tables resemble arrays:

        >>> PUT {} IN tel
        >>> PUT 4054 IN tel["Jennifer"]
        >>> PUT 4098 IN tel["Timo"]
        >>> PUT 4134 IN tel["Guido"]

        >>> WRITE tel["Jennifer"]
        4054

You can write all ABC values out. Tables are kept sorted on the keys:

        >>> WRITE tel
        {["Guido"]: 4134; ["Jennifer"]: 4054; ["Timo"]: 4098}

The keys function returns a list:

        >>> WRITE keys tel
        {"Guido"; "Jennifer"; "Timo"}

        >>> FOR name IN keys tel:
               WRITE name, ":", tel[name] /
        Guido: 4134
        Jennifer: 4054
        Timo: 4098

You can define your own commands:

        HOW TO DISPLAY t:
           FOR name IN keys t:
              WRITE name0, t[name] /

        >>> DISPLAY tel
        Guido      4134
        Jennifer   4054
        Timo       4098

To find the user of a given number, you can use a quantifier:

        >>> IF SOME name IN keys tel HAS tel[name] = 4054:
               WRITE name
        Jennifer

Or create the inverse table:

        >>> PUT {} IN subscriber
        >>> FOR name IN keys tel:
               PUT name IN subscriber[tel[name]]

        >>> WRITE subscriber[4054]
        Jennifer

        >>> WRITE subscriber
        {[4054]: "Jennifer"; [4098]: "Timo"; [4134]: "Guido"}

Commands and functions are polymorphic:

        >>> DISPLAY subscriber
        4054       Jennifer
        4098       Timo
        4134       Guido

Functions may return any type. Note that indentation is significant - there are no BEGIN-END's or { }'s:

        HOW TO RETURN inverse t:
           PUT {} IN inv
           FOR k IN keys t:
              PUT k IN inv[t[k]]
           RETURN inv

        >>> WRITE inverse tel
        {[4054]: "Jennifer"; [4098]: "Timo"; [4134]: "Guido"}

        >>> DISPLAY inverse inverse tel
        Guido      4134
        Jennifer   4054
        Timo       4098