> Given that Rebol is not strongly typed, is the second of these "idioms"

I thought Rebol is strongly typed (but not statically) ... like a value  
has always an assigned type.

About the rest: I prefer to have the interpreter checking the types of the  
arguments if that is wished. Actually I would like to have real support  
for Design by Contract (pre- and postconditions and maybe  
object-invariants), but I'm not sure whether that fits will with the Rebol  
philosophy - but however I find in principle nothing bad in having it. I  
know there is some old implementation of it at Rebol.org, but nobody seams  
to use it - maybe because of some other reasons ?

I guess if you return 'none in case of error, that would somewhat destroy  
the purpose of a function (some precondition is always implied - if not  
explicitely stated), unless returning 'none would be raised to some  
standard, but then other problems occur (like Andreas Bolka stated in the  
other post). Maybe that's why I like the DBC approach, you just state  
what's else implicit in the function explicitely and the user/client of  
the function has to take care to fullfill the precondition and everything  
will work fine.

Are there any comments regarding DBC being (un)useful for Rebol ?

Michael

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