On 8 Feb 2008, at 8:38 am, Dan Weston wrote:
I know that naming is arbitrary, but...
Digits in types seems ugly to me. In this case, it is also
redundant. Everyone but FORTRAN programmers counts from 0, not 1.
Nat and Pos seem clear. Nat0 could even mean Nat \ {0}, the
opposite of what is proposed, so confusion is even increased with
Nat0.
For what it's worth, the Ada names for the types
{x in Z | x >= 0}
and {x in Z | x > 0}
are "Natural" and "Positive" respectively. Natural is useful for
counting stuff;
Positive is useful mainly because Ada practice is to index from 1.
In Z, |N is used for natural numbers, which are defined to include 0.
In modern set theory, both the cardinal and the ordinal numbers start
with
0, not with 1.
All things considered, I would be very upset indeed if a type called
"Nat"
or "Natural" or something like that did not include 0.
_______________________________________________
Haskell-Cafe mailing list
Haskell-Cafe@haskell.org
http://www.haskell.org/mailman/listinfo/haskell-cafe
