Re: Re[2]: Tuple-like constructors

Robert Dockins writes:

instance (Bin a,Bin b,Bin c,Bin d) => Bin (a,b,c,d)

See the problem? Sooner or later (probably sooner) I'll get tired of typing. I have to write down an 'instance' declaration for each value of n. Clearly this can't generalize to all n.

There has been a suggestion that the 'deriving' mechanism be de-coupled from the datatype declaration. Together with a generic default definition, that means you could write something like deriving Bin for (,,,,,,,,,,,,,,,,,,,,) and hence not need to write the tedious instance header yourself, since the compiler can easily infer it. Regards, Malcolm