[Haskell-cafe] money type ?

[Bayley, Alistair]

> From: Brandon S. Allbery KF8NH [mailto:allbery at ece.cmu.edu] 
> 
> I was playing with that when your message came in:
> 
> > mress:5003 Z$ cat foo.hs
> > import Data.Fixed
> >
> > data E2 = E2
> > instance HasResolution E2 where
> >   resolution _ = 100
> > type Money = Fixed E2
> >
> > ...
> > *Main> :m +Data.List
> > *Main Data.List> let l = [1.25 :: Money,2.00,4.46,12.80,1.15,6.00]  
> > in sum l / genericLength l
> > 4.61
> 
> That what you want?

Yes... I'm now wondering how one would read Money values. There's a Show instance for Fixed, but no Read. Could use:

readMoney :: String -> Money
readMoney s = let d :: Double; d = read s in realToFrac d

... but is there a better way? Note that readMoney is a bit dumb:

*Main> readMoney "3.149999"
3.14

Alistair
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