instances for bottom?

Keean Schupke k.schupke at imperial.ac.uk
Tue Nov 23 05:06:22 EST 2004


I was wondering whether the method by which default types are chosen
for unresolved overloading could be made available to the programmer. It 
seems
that if we consider the overlapping instances:

    class x
    instance Int
    instance Float
    instance x

x overlaps with Int and Float... I was wondering if it were possible to 
determine
that type inferance had failed... like with:

    show (read x :: y)

Here y (the type of read x) has no type... and does not match _any_ 
instance apart
from 'x'... so would it not be possible to have an instance for "no type"?

perhaps:

    instance _|_ ...

Keean. 




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