Email Gateway (Aug 19 2022 at 11:22): Email Gateway (Aug 19 2022 at 11:22):From: Christian Sternagel <c.sternagel@gmail.com>
Dear all,
is it possible to use type classes without any class parameters (i.e.,
fixed constants)?
For example, something like
class infinite =
assumes infinite: "infinite (UNIV::'a set)"
but then the resulting type of the class predicate is
term class.infinite
:: "'a itself ⇒ bool
I'm not sure whether this would make sense at all. My initial thought
was to replace assumptions like
assumes "infinite (UNIV :: 'a)"
by "'a :: infinite" in appropriate places.
cheers
chris
Email Gateway (Aug 19 2022 at 11:22):From: Brian Huffman <huffman.brian.c@gmail.com>
On Jul 25, 2013 9:30 AM, "Christian Sternagel" <c.sternagel@gmail.com>
wrote:
Dear all,
is it possible to use type classes without any class parameters (i.e.,
fixed constants)?For example, something like
class infinite =
assumes infinite: "infinite (UNIV::'a set)"
Yes, that is certainly possible. See for example class "finite" from the
standard libraries.
The problem with a type class for infinite types is that you can't quite
define the instances you want. For example, 'a*'b is infinite if either 'a
OR 'b is infinite, but you can't express this with an instance declaration.
Last updated: Nov 21 2024 at 12:39 UTC