It doesn't make sense to have enumerated types implement num::One, num::Zero, or std::ops::Add.

[RobertDurfee]

The convenience constructors (e.g. closed or all) were originally designed for numeric types. The same traits used for numeric types do not work well with enumerated types. A better set of traits would include std::iter::Step (available only with nightly) and std::default::Default. The num::Bounded trait could still be used, but it might be a little confusing because enumerated types are not numeric.

Workarounds:

• The Segment struct does not require the use of convenience constructors to operate correctly (they are there for convenience). If your type cannot implement num::One, num::Zero, or std::ops::Add, then just use the new constructor which makes a closed-open interval.

[RobertDurfee]

Created new traits Bounded and Next which make more sense for enumerated types. std::default::Default is now used instead of num::Zero to remove implicit requirement for numeric types.

Fixed with 11c81d7.