On Sep 5, 2007, at 6:47 , Ketil Malde wrote:
On Wed, 2007-09-05 at 09:56 +0100, Simon Peyton-Jones wrote:
Good point. Not so easy for multi-parameter type classes! E.g. No
instance for (Bar String Int). So we could have
String is not an instance of class Foo -- single param
No instance for (Bar String Int) -- multi-
param
If you quote things, you can also consider:
'String Int' is not an instance of class 'Bar'.
Downside is that 'String Int' by itself may be confusingly
unhaskellish.
I'd phrase it instead as:
Class "Num" has no instance for "String"
Class "Num" has no instance for "Complex"
Class "Bar" has no instance for "String" and "Int"
(or maybe ("String","Int") since it's conceptually similar to a
tuple, and the formulation above could conceivably be misconstrued as
looking for separate instances for String and Int?)
--
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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