In article , Taral wrote:

On 3/19/06, Ashley Yakeley wrote:

...

1. Adding my Data.Fixed module to the base package. http://semantic.org/TimeLib/doc/html/Data-Fixed.html http://darcs.haskell.org/packages/time/fixed/Data/Fixed.hs

When would you used a (Fixed a) without (HasResolution a)?

Never as far as I can imagine. The 'a' parameter will be taken by a phantom type. http://haskell.org/haskellwiki/Phantom_type The two I have, E6 and E12, represent 10^6 and 10^12, but you could use some other number, such as a power of 2. -- Ashley Yakeley, Seattle WA WWED? http://www.cs.utexas.edu/users/EWD/

Taral wrote:

Now I don't recall, but is it allowed to do:

data HasResolution a => Fixed a = ...?

Not usefully. data T a = MkT a data C a => T a = MkT a It's allowed, but it doesn't do what you probably want. All it does is change the type of the constructor MkT. If the parameter "a" to Fixed is free, we don't particularly want to hide away the HasResolution constraint on it somehow. Of course, once it's specialised as a particular type (e.g. Fixed E12), then it's not needed anymore. -- Ashley Yakeley, Seattle WA WWED? http://www.cs.utexas.edu/users/EWD/