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[REBOL] Re: Evaluator of expressions with 'where clause

From: rotenca:telvia:it at: 22-Oct-2002 13:53

Hi Jan Skibinski
> What is a difference between 'any and 'any-type? > I noticed that the help utility sometimes responds > with the former and sometimes with the latter. > Is there any special meaning in it, or is this > a matter of an accidental ora historical nature? > Does it have anything to do with a differentiation > between the native! and the function!? > Or explicit/implicit unknown argument types?
When a function is without explicit type, it is visualized by Help with 'any (it is only an help feature, cannot be used as specification for a function argument). 'Any-type! means: any argument, also unset! argument, no argument, error! argument. x2: func [a [any-type!]][value? 'a] x2 ;== false x2 print "" ;== false x2 make error! "" ;== true 'Any means: one argument, not unset! and error!. x: func [a][value? 'a] x; ** Script Error: x is missing its a argument ** Near: x x print "" ;** Script Error: x is missing its a argument ** Near: x print "" x make error! "" ;** User Error: ** Near: x make error! "" --- Ciao Romano