[Haskell-cafe] deriving
PR Stanley
prstanley at ntlworld.com
Mon Apr 7 12:43:10 EDT 2008
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?
>Discuss :-)
>
>Cheers,
>Paul
>I'm not getting it. Are you thinking that Bool itself "is derived
>from these classes", rather than those four instances for Bool? - Conal
>Paul:
>I am aware that Bool is an instance of Eq, Ord, ... What I'm not
>sure about is the terminology used here. Deriving, deriving what
>from Eq, Ord, ...? How about
data Bool = False | True
from (Eq, Ord, Show, Read)
although I have a feeling that "from" is already used somewhere in Haskell.
Paul
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