REBOL 3.0

What does () mean?

Carl Sassenrath, CTO
REBOL Technologies
5-Mar-2008 4:41 GMT

Article #0011
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In R2, () was an error.

In R3, () returns the value: UNSET!

So:

>> mold ()
== "unset!"

It's debatable.

We must admit that it does represent a valid expression. This can be seen in functions that allow missing arguments, such as:

>> cd
/C/rebol/3.0
>> cd %..
/C/rebol/

which are valid anywhere if you use parens:

>> (cd)
/C/rebol/3.0
>> (cd %..)
/C/rebol/

So, in the (cd) case, the missing argument for path is given the value UNSET!

Mathematically, () is the trivial case. QED.

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REBOL 3.0
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