Thanks for all the replies.
I'm nervous about fixing the arity of Unit, in any language used for
commercial applications.
Herbert Graeber writes:
> [...]
>
> Using C++, one can define templates for proper handling of units without
> additional language extensions:
>
> template <int l, int t>
> class Unit {
> ...
> };
>
> [...]
Christian Sievers writes:
> [...]
>
> > sqrt :: (m::Int) |-> (l::Int) |-> (t::Int) |->
> > Unit (2*m) (2*l) (2*t) -> Unit m l t
>
> [...]
The S.I. units are stable. However, currency units benefit from the
same treatment, with each currency as a separate dimension (assuming
that compilers should not be exchange rate aware), and a commercial
application may need to deal with any number of currencies.
Then, there's the issue of letting the end users define additional
currencies at run time. I see a couple of ways to deal with this:
1. Don't attempt to type-check currency at compile time. Fix the
arity of Unit after all, if that helps with anything.
2. Deem the currency-defining task to be programming, not a true end
user activity. Deem your application's configuration parameters
to be a programming language.
Regards,
Tom
