Hugs-98-September-1999
cannot load the package DoCon-2 <http:/haskell.org/docon>,
while the May-99 version and ghc-4.04 can do this.
The story is as follows.
--------------------------------------------------------------------
Download and unzip DoCon-2.
Prepare Hugs-98 and the hugso starter as it is said in
install.txt
of DoCon.
> hugso
...
..> :l DExport
First, it reports (unlike Hugs-98-May) the error in auxil/Categs_.hs
with deriving(Show) in
data OSet a =
OSet {osetSample :: !a, -- sample for Base set
membership :: !(Char -> a -> Bool),
--------------------
...
}
deriving(Show)
All right, in Categs_.hs, we remove `deriving(Show)' from
data OSet ...,
data Subsemigroup ...,
data Subgroup ...,
data Subring ...,
- probably, they apply `deriving' not so correct.
Now,
..> :l DExport
reports
ERROR "/usr/ghc/d/docon/source/residue/ResEuc_.hs" (line 122):
Cannot build superclass instance
*** Instance : AddSemigroup (ResidueE a)
*** Context supplied : EuclideanRing a
*** Required superclass : Set (ResidueE a)
This is strange. Because ResEuc_.hs contains the declaration
instance (EuclideanRing a) => Set (ResidueE a) ...
at the line 103
and
instance (EuclideanRing a) => AddSemigroup (ResidueE a) ...
at the line 122.
Is it a Hugs bug?
Another question:
install.txt of DoCon, does it say correct things on Hugs
installation and setting environment?
------------------
Sergey Mechveliani
[EMAIL PROTECTED]
