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Re: The ". $" notation (was: Re: how useful are collecting lists?)



Alan Manuel Gloria:
> To reduce the parentheses, we could (I propose!!) do:
> 
> cut .
>   proc arg arg <> arg arg <...>

Ugh. I *really* don't see the value of this form, and
allowing "." at the end disables some error checking
I don't really want to disable.  Seems to me that
people would normally write:

cut proc arg arg <> arg arg <...>

I also suspect there may be implementation problems.

> Or alternatively:
> 
> cut . $ proc arg arg <> arg arg <...>

I doubt I would *personally* use this, and I'm skeptical
that it adds much.  But on the other hand
I don't see any harm, especially since
we have to check after "." anyway for special cases, and
that seems like an improbable construct to use *accidentally*.

So I'd be okay with adding this.

Again, I'd just write:
cut proc arg arg <> arg arg <...>


> Basically, in the case of cut, while ". $" is effectively a no-op, it
> separates, syntactically, the procedure call from the form that
> provides a limited extension of the procedure call's semantics (in the
> case of cut, it adds <> and <...> syntaxes).  A user might, in the
> future, be able to think of other extended formulations which ". $"
> could then support.

> So my proposal is:
> 
> 1.  Allow "foo . EOL INDENT x ..." ==> "(foo . (x ...))"

Worried about this one.

> 2.  Allow "foo . $ x ..." ==> "(foo x ...)"

I could get talked into this one, though I can't imagine using it.

> What does everyone think??

I'd sure like to know too!

--- David A. Wheeler