Method CompareTo

Namespace

SodaFlow.Functional

Assembly

SodaFlow.Functional.dll

CompareTo(Maybe<T>)

Puts this instance in order against a second one, and a missing value comes first.

public int CompareTo(Maybe<T> other)

Parameters

other Maybe<T>

The instance to compare against.

Returns

int

A negative number when this sorts before other, and a positive number when this sorts after it. Zero when no one of the two sorts before the other.

Remarks

No value sorts before each value. That is how Default puts a Nullable<T> in order, thus it is the answer with the fewest surprises. This puts two instances that each have a value in order by Default for T, which throws when T has no ordering. That is the same failure, at the same point, as an order of bare T values gives. This reads Default where operator ==(Maybe<T>, Maybe<T>) reads Default . Take a type whose ordering and equality disagree, and string is one: the culture gives its order, and an ordinal compare gives its equality. Thus, a zero result here does not have to mean that operator ==(Maybe<T>, Maybe<T>) gives true. This inherits that from those two comparers, and an order of bare T values does the same. There are deliberately no < and > operators to go with this. Nullable<T> has them, and they are a trap. They answer false in the two directions when one side is missing, thus !(a < b) stops to mean a >= b. A sort is what needs an ordering, and a sort uses this method.