[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: #f = #none ?
- To: Stavros Macrakis <email@example.com>
- Subject: Re: #f = #none ?
- From: cfry@MIT.EDU (Christopher Fry)
- Date: Wed, 18 Nov 92 16:20:17 EST
- Cc: firstname.lastname@example.org
> Date: Wed, 18 Nov 1992 10:57:42 -0500
> To: email@example.com
> Subject: #f = #none ?
> From: Stavros Macrakis <firstname.lastname@example.org>
> Sender: email@example.com
> Imagine a function which takes an optional argument which is to be
> True, False, or Dont-care. Presumably if the argument is omitted, the
> value should be Dont-care. How will we encode these values? We can't
> use #f for False, because it also means that the argument isn't there.
> We could use #t for true, but we'll have to be careful, because all
> boolean functions in Dylan allow any non-#f value to represent
> So perhaps we'll need to define a new type which takes values
> (singletons) True, False, and #f... Seems silly, and error-prone.
This reminds me of a problem with CL. If Dylan doesn't address it, it
should. For an argument in a function call, I would like to explicitly