On Sat, Oct 23, 2021, 10:58 PM Steven D'Aprano
> > ... On the other hand, if this could express a much more general
> deferred computation, I'd be really enthusiastic (subject to syntax and
> behavioral details).
> >
> > However, I recognize that a new general "dynamically scoped lambda"
> would indeed have a lot of edge cases.
>
> Dynamic scoping is not the same as deferred computation.
>
Of course not generally. But a dynamic deferred could cover this specific
desire of the proposal.
So stawman proposal:
def fun(seq, low=0, high=defer: len(seq)):
assert low < high
# other stuff...
Where the implication here is that the "defer expression" creates a dynamic
scope.
The reason this could appeal to me is that it wouldn't be limited to
function signatures, nor even necessarily most useful there. Instead, a
deferred object would be a completely general thing that could be bound
anywhere any object can.
Such a capability would allow passing around potential computational "code
blocks", but only perform the work if or when a value is required.
>
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