[Haskell-cafe] resolving missing class instances @ compile time

Greg Buchholz haskell at sleepingsquirrel.org
Thu May 12 14:58:00 EDT 2005


Bernard Pope wrote:
> 
> Perhaps this section of the report might help:
> 
> >From Section "4.3.2 Instance Declarations" in the Haskell Report:
> 
>    http://www.haskell.org/onlinereport/decls.html#instance-decls
> 
> "If no binding is given for some class method then the corresponding
> default class method in the class declaration is used (if present); if
> such a default does not exist then the class method of this instance is
> bound to undefined and no compile-time error results."

    I may be missing the big picture, but why is this behavior more
desirable than failing with an error at compile time?
    
Greg Buchholz


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