[SCL] Is the notion of predicate position abstract or abstractable?

[Tanel Tammet]

Hi,

Robert E. Kent wrote:

>Examples in the SCL specification (and other realms) are very important in
>getting our abstractions correct. I have been bothered for some time about
>our desire for abstraction in the SCL (witness the SCL abstract syntax
>discussion) and the notion in the SCL spec regarding "predicate position",
>which seems intuitively to be a rather concrete notion. 
>
What I have found helpful for this somewhat philosophical question
is thinking about combinatory logic: you know, the two simple equalities
for S and K combinators. This basic formulation of both logic and 
computation
at the same time is both highly abstract and highly concrete, in
some sense. In this respect there is IMHO not much to invent
in the SCL context: the deep, basic inventions have been done long
ago. People can go further,  of course,  but I suspect that SCL
is not the best context for really groundbreaking developments.
The whole spectrum of SW questions might be a good context,
though.

I'd rather think about the SCL process as picking the well-known
abstractions which seem to be pragmatic in the context
of SW languages.

Regards,
            Tanel Tammet