Difference Argument Order

[ajb at spamcop.net]

G'day all.

Quoting Ashley Yakeley <ashley at semantic.org>:

> Which of these argument orders is more intuitive to you?

This one:

> 2. This one is more familiar for the English language and for the
> standard operators:
>
> add :: Absolute -> Diff -> Absolute
> add a d = a + d
> subtract :: Absolute -> Diff -> Absolute
> subtract a d = a - d
> diff :: Absolute -> Absolute -> Diff
> diff a b = a - b

But even better would be if you could do both, and not distinguish between
subtract and diff:

    class Add a b c | a b -> c where
        add :: a -> b -> c

    class Subtract a b c | a b -> c where
        subtract :: a -> b -> c

...you get the idea.

Cheers,
Andrew Bromage