[Haskell-cafe] Unique Ordered Types

Silvio Frischknecht silvio.frischi at gmail.com
Wed Aug 12 23:24:54 UTC 2015

Looks very nice. A bit large for my taste though. Anyway, it seems they
can't order their units either.

That's why

(|+|) :: (d1 @~ d2, Num n) => Qu d1 l n -> Qu d2 l n -> Qu d1 l n

and not

(|+|) :: (Num n) => Qu d l n -> Qu d l n -> Qu d l n

This will always be a bit annoying. You can almost never safely write

Qu (Foo :* Bar) l n

but will always have to write

(d @~ (Foo :* Bar)) => Qu d l n

in your types.


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