On Saturday, 13 September 2014 at 19:39:03 UTC, Andrei
Alexandrescu wrote:
On 9/13/14, 8:36 AM, bearophile wrote:
This is a little Haskell program that uses the Maybe type
constructor:
[snip]
As others noted, I think we need a kind of range with either
zero or one element. Also, the range would have an "exception"
property that returns null if the operation was successful (and
the element is there) or whatever exception produced the
result. E.g.:
MaybeRange fun() { ... }
...
auto r = fun;
if (r.empty)
{
assert(r.exception);
... error case ...
What if the operation failed without producing an exception?
I.e., if we wrap an API that signals errors by returning false
for example, do we really need to create an exception just to
store it in `r.exception`?
}
else
{
... use r.front ...
r.popFront;
assert(r.empty); // just one element
}
Andrei
