Overlapping and incoherent instances

[Johan Tibell]

On Wed, Jul 30, 2014 at 2:50 PM, Ivan Lazar Miljenovic
<ivan.miljenovic at gmail.com> wrote:
> On 30 July 2014 22:07, Andreas Abel <andreas.abel at ifi.lmu.de> wrote:
>> I am a bit surprised by the distinction you outline below.  This is maybe
>> because I am native German, not English.  The German equivalent of
>> "overlap", "überschneiden/überlappen", is used exclusively in a symmetrical
>> fashion.  It's like in English, if I say "our interests overlap", then it is
>> pointless to ask whether my interest are overlapping yours or are overlapped
>> by yours.  I want to alert you to the fact that non-native English speaker
>> might have little understanding for a distinction between "OVERLAPPING" and
>> "OVERLAPPABLE".
>>
>> Let's try to guess what it meant:  Given
>>
>> A) instance Bla Char
>> B) instance Bla a => Bla [a]
>> C) instance Bla String
>>
>> you will in context A,B write C as OVERLAPPING,
>> and in context A,C write B as OVERLAPPABLE?
>
> IIUC, B will be OVERLAPPABLE ("you can overlap this") and C will be
> OVERLAPPING ("I'm overlapping an existing one") whereas C will be
> plain.

Apologies if this question doesn't make sense.

Can we really talk about overlapping, given that instances can be
written in different modules, moved between modules, or removed?