SetSemilattice

Given Eq[A], return a PartialOrder[A] using the combine operator to determine the partial ordering. This method assumes combine functions as join (that is, as an upper bound).

This method returns:

0.0 if x = y -1.0 if y = combine(x, y) 1.0 if x = combine(x, y) NaN otherwise

Given Eq[A], return a PartialOrder[A] using the combine operator to determine the partial ordering. This method assumes combine functions as meet (that is, as a lower bound).

This method returns:

0.0 if x = y -1.0 if x = combine(x, y) 1.0 if y = combine(x, y) NaN otherwise

Given a sequence of as, sum them using the monoid and return the total.

Example:

scala> import cats.kernel.instances.string._

scala> Monoid[String].combineAll(List("One ", "Two ", "Three"))
res0: String = One Two Three

scala> Monoid[String].combineAll(List.empty)
res1: String = ""

Tests if a is the identity.

Example:

scala> import cats.kernel.instances.string._

scala> Monoid[String].isEmpty("")
res0: Boolean = true

scala> Monoid[String].isEmpty("something")
res1: Boolean = false