List syntax (was: Re: help from the community?)
dgou at mac.com
Fri Feb 2 12:41:04 EST 2007
On 2007 Feb 2, at 12:13 PM, Kirsten Chevalier inquired:
> On 2/2/07, Douglas Philips <dgou at mac.com> wrote:
>> I assert that the trailing comma is a feature, not a programmer
>> forgetting "the last element", and that this
>> is already explicitly allowed, as per the syntax fragments already
>> quoted, repeated here for convenience:
>> -- from: http://www.haskell.org/onlinereport/syntax-iso.html#sectB.4
>> impspec -> ( import1 , ... , importn [ , ] )
>> | hiding ( import1 , ... , importn
>> [ , ] ) (n>=0)
>> exports -> ( export1 , ... , exportn [ , ] )
> Huh? I don't quite see what you're getting at here. The report says
> that the trailing comma is allowed in import and export lists, yes.
> But you were talking about trailing commas in lists and tuples, which
> would be a change to the existing language, not something that's
> "already explicitly allowed". Can you clarify what you meant?
Hmmm...stated another way:
I am proposing that the list and tuple syntax change to be consistent
with the import and export syntax.
The argument that a trailing comma "means" "the programmer forgot the
last item" in a list / tuple is
inconsistent with the deliberately explicit permissiveness of a
trailing comma in the import / export lists.
In the import / export lists such a trailing comma does not mean
"programmer forgot additional thing at the end."
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