Hugs for Macs different from Hugs for Suns ??

[Johan Nordlander]

On Monday, June 11, 2001, at 06:02  AM, Peter Padawitz wrote:

> Using the type definition:
>
>  data Term a = T a [Term a]
>
> I run the precomplied Hugs version on a Mac and another one 
> under Sun OS.
> The first accepts the instance definition:
>
>  instance Show (Term String) where ..
>
> The second reports
>
>  syntax error in instance head (variable expected)
>
> and accepts if I write:
>
>  instance Show a => Show (Term a) where ..
>
> Why do the systems react differently???
>
> Best regards,
>
> 	Peter
>

Hi Peter,

Your first instance declaration above isn't strictly Haskell 98 
code, Hugs needs the -98 flag in order to accept this form of 
instances.  Type hugs -98 on your Sun machine and the example 
will compile just fine.

Somewhat unfortunately, the Mac version runs in -98 mode by 
default because of the contents of the supplied file "Hugs 
Preferences" in the Hugs root folder.  You can edit this file to 
suit your own preferences; still, you were right in expecting 
the default configuration to be the same on all platforms.

Thanks for bringing this inconsistency to my attention.  It will 
be fixed in the forthcoming release.

All the best,
Johan