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This seems like an entire extra dimension of complexity, if we do it
right. What happens if you pass a question-marked nil into setfenv? If
you use it to create a coroutine? The "and" idiom, while
wacky-looking, is at least a simple and easily understood method of
doing this.

On Sun, 27 Jun 2004 23:42:14 -0700, Mark Hamburg <> wrote:
> Would it be useful to define syntactic sugar that would allow nils to turn
> into no-ops? For example, what if:
>     x = expr?.field
> Were sugar for:
>     local var = expr;
>     x = expr and expr.field
> In other words, ?. applied to nil yields nil. Similarly for ?[].
> func?() could result in a call to a function returning nothing if func was
> nil. (I leave it as an open point of discussion whether any arguments get
> evaluated. They probably do.)
> obj?:message() would be like a call to a function returning nothing if obj
> was nil. Similarly, for obj:message?() if obj fails to support message. If
> both are optional, then one writes: obj?:message?().
> I find myself writing a fair amount of code that avoids going down a path
> when something is nil and if this is a common pattern for other people it
> might be useful to encode it in some form of syntactic sugar.
> Mark