Simon Marlow warned (i do not know whether the docs mentions this)
that deriving (...)
can be very expensive for compiling with ghc-4.02
- especially, for Show, Read.
Now, comparing
data CategoryName =
Set | AddSemigroup | AddGroup | MulSemigroup | MulGroup
| Ring | LinSolvRing | GCDRing | FactorizationRing
| EuclideanRing | IdealKey | LeftModule | LinSolvLModule
deriving (Show)
and the same - with `deriving' replaced with the explicit instance
instance Show CategoryName
where
showsPrec _ x = case x of
Set -> (" Set "++)
AddSemigroup -> (" AddSemigroup "++)
...
shows that `deriving' gives 1.5 times smaller code.
And i really need here Eq, Ord, Enum, Show - they are not dummies.
Looks like it is better for me to derive them.
And the Simon's warning is for remembering that the effect is about as
if one sets these instances manually.
Do i understand correct?
------------------
Sergey Mechveliani
[EMAIL PROTECTED]
