Checked integer type API design poll

[tsbockman via Digitalmars-d]

I have written some poll questions concerning the design 
trade-offs involved in making a good `SafeInt`/`CheckedInt` type. 
They are about the actual semantics of the API, not the 
internals, nor bike-shedding about names.

(`SafeInt` and `CheckedInt` are integer data types which use 
`core.checkedint` to guard against overflow, divide-by-zero, etc. 
Links to current work-in-progress versions by

1) Robert Schadek (burner):
     https://github.com/D-Programming-Language/phobos/pull/3389
2) Myself (tsbockman):
     https://github.com/tsbockman/CheckedInt)

For the purposes of this poll please assume the following (based 
on my own extensive testing):

1) Code using checked operations will take about **1.5x longer to 
run** than unchecked code. (If you compile with GDC, anyway; DMD 
and LDC are another story...)
2) The main design decision with a significant runtime 
performance cost, is whether to throw exceptions or not. With 
some optimization, the hit is modest, but noticeable.
3) Even if the API uses exceptions some places, it can still be 
used in `nothrow @nogc` code, at the cost of some extra typing.

Two further points I would ask the reader to consider:

* A checked integer type is fundamentally semantically different 
from an unchecked type. The difference is of similar magnitude to 
that of floating-point vs fixed-point.
* It might be wise to read the entire poll before answering it - 
the questions are all related in some way.

The poll results are here, if you wish to preview the questions:
     
http://polljunkie.com/poll/kzrije/checked-integer-type-behaviour/view
When you are ready, please take the poll yourself:
     
http://polljunkie.com/poll/cytdbq/checked-integer-type-behaviour

Thanks for your time.