[REBOL] Re: Function Context Query
From: lmecir:mbox:vol:cz at: 6-Dec-2001 18:21
Hi Romano,
<<Romano>>
(...)
An unset word is a word with the value unset. It is like any other value and
any other word. If you use it where a function ask a value, Rebol triggers
an
error. But Rebol triggers the same error if you pass an argument of type
integer! where a function ask for a value of type unset:
>> x: func [a [unset!]][value? 'a]
>> do [x ()]
== false
>> do [x 1]
** Script Error: x expected a argument of type: unset
** Near: x 1
BTW, I think that the name of function value? is confusing. It should be
something like: not-unset-value?
And also unset is confusing, because you can set a word at the unset value:
>> set/any 'a ()
>> value? 'a
== false
my conclusion: unset <> no value
(...)
<</Romano>>
yes! Another example: (block: reduce [()]). BLOCK will not be empty. Will it
contain
a value?
