Difficulties in implementation of textToInterval(s)
The section 12.12.7 of the original IEEE 1788 standard has the text
about "difficulties in implementation".
It explains difficulties of testing the condition "l <= u".
Later in the text it allows constructors to succeed ("false positives")
when l and u are close to each other
and implementation can't determine for sure that "l <= u".
The condition when this case might occur shall be documented.
PossiblyUndefinedOperation exception must be signaled in this case.
This difficulty doesn't happen in P1788.1 with numsToInterval(l,u) constructor
because l and u are both b64 numbers.
However, it might happen in P1788.1 with textToInterval(s) constructor.
The P1788.1 omits the text about "difficulties in implementation" and about PossiblyUndefinedOperation.
The section 6.7.4 of the suggested Level2 chapter of P1788.1 requires stricter behaviour.
It requires textToInterval(s) to fail and to return empty interval when s is not valid.
The section 6.6.2 says that an interval literal [l,u] is valid iff "l <= u".
So the operation textToInterval(s) for some inputs is more expensive in P1788.1 than in P1788.
Is it intentional project decision of P1788.1 ?
-Dima