UnitAlgebra

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 = ""

Return a appended to itself n times. If n is negative, then this returns inverse(a) appended to itself n times.

Like compare, but returns a cats.kernel.Comparison instead of an Int. Has the benefit of being able to pattern match on, but not as performant.

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

Like partialCompare, but returns a cats.kernel.Comparison instead of an Double. Has the benefit of being able to pattern match on, but not as performant.

Returns Some(x) if x >= y, Some(y) if x < y, otherwise None.

Returns Some(x) if x <= y, Some(y) if x > y, otherwise None.

Remove the element b from a.

Equivalent to combine(a, inverse(b))

Example:

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

scala> Group[Int].remove(5, 2)
res0: Int = 3

Convert a Order[A] to a scala.math.Ordering[A] instance.

Result of comparing x with y. Returns None if operands are not comparable. If operands are comparable, returns Some[Int] where the Int sign is:

• negative iff x < y
• zero iff x = y
• positive iff x > y