-
-
Notifications
You must be signed in to change notification settings - Fork 1.2k
/
AlignLaws.scala
69 lines (59 loc) · 2.45 KB
/
AlignLaws.scala
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
/*
* Copyright (c) 2015 Typelevel
*
* Permission is hereby granted, free of charge, to any person obtaining a copy of
* this software and associated documentation files (the "Software"), to deal in
* the Software without restriction, including without limitation the rights to
* use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
* the Software, and to permit persons to whom the Software is furnished to do so,
* subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all
* copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
* FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
* COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
* IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
package cats
package laws
import cats.syntax.align._
import cats.syntax.functor._
import cats.data.Ior
import cats.data.Ior.{Both, Left, Right}
/**
* Laws that must be obeyed by any `Align`.
*/
trait AlignLaws[F[_]] {
implicit def F: Align[F]
implicit val functor: Functor[F] = F.functor
def alignAssociativity[A, B, C](fa: F[A], fb: F[B], fc: F[C]): IsEq[F[Ior[Ior[A, B], C]]] =
fa.align(fb).align(fc) <-> fa.align(fb.align(fc)).map(assoc)
def alignHomomorphism[A, B, C, D](fa: F[A], fb: F[B], f: A => C, g: B => D): IsEq[F[Ior[C, D]]] =
fa.map(f).align(fb.map(g)) <-> fa.align(fb).map(_.bimap(f, g))
def alignWithConsistent[A, B, C](fa: F[A], fb: F[B], f: A Ior B => C): IsEq[F[C]] =
fa.alignWith(fb)(f) <-> fa.align(fb).map(f)
private def assoc[A, B, C](x: Ior[A, Ior[B, C]]): Ior[Ior[A, B], C] =
x match {
case Left(a) => Left(Left(a))
case Right(bc) =>
bc match {
case Left(b) => Left(Right(b))
case Right(c) => Right(c)
case Both(b, c) => Both(Right(b), c)
}
case Both(a, bc) =>
bc match {
case Left(b) => Left(Both(a, b))
case Right(c) => Both(Left(a), c)
case Both(b, c) => Both(Both(a, b), c)
}
}
}
object AlignLaws {
def apply[F[_]](implicit ev: Align[F]): AlignLaws[F] =
new AlignLaws[F] { def F: Align[F] = ev }
}