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[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?