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scaladoc fixes for PartialOrder #3732

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Jan 13, 2021
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scaladoc fixes for PartialOrder #3732

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31 changes: 17 additions & 14 deletions kernel/src/main/scala/cats/kernel/PartialOrder.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -9,29 +9,31 @@ import compat.scalaVersionSpecific._
*
* A partial order is defined by a relation <=, which obeys the following laws:
*
* - x <= x (reflexivity)
* - if x <= y and y <= x, then x = y (anti-symmetry)
* - if x <= y and y <= z, then x <= z (transitivity)
* - x <= x (reflexivity)
* - if x <= y and y <= x, then x = y (anti-symmetry)
* - if x <= y and y <= z, then x <= z (transitivity)
*
* To compute both <= and >= at the same time, we use a Double number
* to encode the result of the comparisons x <= y and x >= y.
* The truth table is defined as follows:
*
* x <= y x >= y Double
* true true = 0.0 (corresponds to x = y)
* false false = NaN (x and y cannot be compared)
* true false = -1.0 (corresponds to x < y)
* false true = 1.0 (corresponds to x > y)
* | x <= y | x >= y | result | note |
* | :-- | :-- | --: | :-- |
* | true |true | 0.0 | (corresponds to x = y) |
* | false |false | NaN | (x and y cannot be compared) |
* | true |false | -1.0 | (corresponds to x < y) |
* | false |true | 1.0 | (corresponds to x > y) |
*/
trait PartialOrder[@sp A] extends Any with Eq[A] { self =>

/**
* Result of comparing `x` with `y`. Returns NaN if operands are not
* comparable. If operands are comparable, returns a Double whose
* sign is:
* - negative iff `x < y`
* - zero iff `x = y`
* - positive iff `x > y`
*
* - negative iff `x < y`
* - zero iff `x = y`
* - positive iff `x > y`
*/
def partialCompare(x: A, y: A): Double

Expand All @@ -46,9 +48,10 @@ trait PartialOrder[@sp A] extends Any with Eq[A] { self =>
* 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`
*
* - negative iff `x < y`
* - zero iff `x = y`
* - positive iff `x > y`
*/
def tryCompare(x: A, y: A): Option[Int] = {
val c = partialCompare(x, y).sign
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