On Apr 7, 2008, at 12:12 , PR Stanley wrote:
Hi
data Bool = False | True
deriving (Eq, Or, Show, Read)
Bool is an instance of Eq, Ord, Show and Read. It is derived form
these classes. If that is the meaning of the keyword deriving then
wouldn't a different keyword such as from or derivative or even
derivation be closer to the semantics of the concept?
"deriving" doesn't declare superclasses; it means "please auto-
generate code for me implementing instances for these classes". See
http://haskell.org/onlinereport for the semantics of automatic
instance deriving.
--
brandon s. allbery [solaris,freebsd,perl,pugs,haskell] [EMAIL PROTECTED]
system administrator [openafs,heimdal,too many hats] [EMAIL PROTECTED]
electrical and computer engineering, carnegie mellon university KF8NH
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