There's some documentation on this in the User's Guide:
http://www.haskell.org/ghc/docs/latest/html/users_guide/x1075.html#GHCI-
DEFAULTING
Cheers,
Simon
On 23 August 2004 17:15, Simon Peyton-Jones wrote:
> The binding
> let t = printQ
> falls under the monomorphism restriction. The Haskell Report would
> not default (Show a), so you might think you'd get an "ambiguous type
> variable" error. But it's so annoying to get this error for
> ghci> show []
> that GHCi is a bit more eager about defaulting ambiguous types: it'll
> apply defaulting if all the constrained classes are standard, and at
> least one of them is numeric *or* is Show, Eq or Ord.
> The *or* part is the non-standard bit.
>
> Admittedly, I'm not sure this is documented.
>
> Simon
>
>> -----Original Message-----
>> From: [EMAIL PROTECTED]
>> [mailto:glasgow-haskell-users- [EMAIL PROTECTED] On Behalf Of
>> Abraham Egnor
>> Sent: 23 August 2004 16:02
>> To: [EMAIL PROTECTED]
>> Subject: overzealous defaulting?
>>
>> I'm not sure if this is an actual bug, as opposed to an odd instance
>> of defaulting:
>>
>> *GUI.Parser> let printQ q = runQ q >>= print
>> *GUI.Parser> :t printQ
>> printQ :: forall a. (Show a) => Q a -> IO ()
>> *GUI.Parser> let p = printQ
>> *GUI.Parser> :t p
>> p :: Q Integer -> IO ()
>>
>> ...but I'm not sure when that would ever be the correct behavior.
>>
>> Abe
>> _______________________________________________
>> Glasgow-haskell-users mailing list
>> [EMAIL PROTECTED]
>> http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
> _______________________________________________
> Glasgow-haskell-users mailing list
> [EMAIL PROTECTED]
> http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
_______________________________________________
Glasgow-haskell-users mailing list
[EMAIL PROTECTED]
http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
