> Date: Sun, 13 Jun 1999 01:51:06 -0400
> From: Kevin Atkinson <[EMAIL PROTECTED]>
> Could some one explain to me why [this is not OK]:
> class T f r
>
> instance T a (d a)
> instance T (c a b) (c a (d b))
Because, just as Hugs says:
> *** Common instance : T (a b c) (a b (a b c
Lars Henrik Mathiesen wrote:
>
> > Date: Sun, 13 Jun 1999 01:51:06 -0400
> > From: Kevin Atkinson <[EMAIL PROTECTED]>
>
> > Could some one explain to me why [this is not OK]:
>
> > class T f r
> >
> > instance T a (d a)
> > instance T (c a b) (c a (d b))
>
> Because, just as Hugs s
Here follows some very preliminary view of how the *rules* could be
introduced to Haskell.
I am not so sure about its scientific quality.
The subject needs studying.
--
Sergey Mechveliani
[EMAIL PROTECTED]
Equational simplifier proposal for Haskell language
***
Hi,
I have been reading "On the expressive power of Constructor Classes" by Erik
Meijer and Luc Duponcheel, where they describe a categorical prelude for
Haskell.
I have three questions:
The paper refers to a forthcoming RUU Research Report, which is to contain a
fuller description of the prel
Could some one explain to me why this is OK:
class T f r
instance T a (a)
instance T (c a b) (c a (b))
but this is not:
class T f r
instance T a (d a)
instance T (c a b) (c a (d b))
as Hugs gives (with -98 +o)
ERROR "T.hs" (line 4): Overlapping instances for class
