diff --git a/datatypes/contt.html b/datatypes/contt.html index 9b8ad02fee..bf85ac21bf 100644 --- a/datatypes/contt.html +++ b/datatypes/contt.html @@ -286,7 +286,7 @@

ContT

Succeeded(user.id) } } -// eval: Eval[UserUpdateResult] = cats.Later@4d8e4574 +// eval: Eval[UserUpdateResult] = cats.Later@3ec2dd0

Finally we can run the resulting Eval to actually execute the computation:

eval.value
 // Persisting updated user to the DB: User(100,Bob,150)
@@ -308,7 +308,7 @@ 
// anotherComputation: ContT[Eval, UserUpdateResult, Map[String, String]] = FromFn(
 //   runAndThen = Single(
-//     f = cats.data.ContT$$Lambda$11937/0x00007f9d0b02c9c8@1e0ce73f,
+//     f = cats.data.ContT$$Lambda$14330/0x00007f9566678d58@4834d16d,
 //     index = 0
 //   )
 // )
@@ -319,7 +319,7 @@ 
Succeeded(userFields("id").toInt)
   }
 }
-// anotherEval: Eval[UserUpdateResult] = cats.Eval$$anon$5@7944bf7c
+// anotherEval: Eval[UserUpdateResult] = cats.Eval$$anon$5@4cab108f
 
 anotherEval.value
 // Persisting these fields to the DB: Map(id -> 100, name -> Bob, age -> 150)
@@ -336,7 +336,7 @@ 
// updateUserModel: ContT[Eval, UserUpdateResult, User] = FromFn(
 //   runAndThen = Single(
-//     f = cats.data.ContT$$Lambda$11937/0x00007f9d0b02c9c8@33b1d2f8,
+//     f = cats.data.ContT$$Lambda$14330/0x00007f9566678d58@31a589fa,
 //     index = 0
 //   )
 // )
@@ -370,7 +370,7 @@ 
updateUserModel flatMap persistToDb flatMap publishEvent
 // chainOfContinuations: ContT[Eval, UserUpdateResult, UserUpdateResult] = FromFn(
 //   runAndThen = Single(
-//     f = cats.data.ContT$$Lambda$11941/0x00007f9d0b02d350@1df1849d,
+//     f = cats.data.ContT$$Lambda$14334/0x00007f95666796e0@35d57122,
 //     index = 0
 //   )
 // )
@@ -381,7 +381,7 @@ 
finalResult
   }
 }
-// eval: Eval[UserUpdateResult] = cats.Eval$$anon$5@1d65cf00
+// eval: Eval[UserUpdateResult] = cats.Eval$$anon$5@4434c02
 
 eval.value
 // Updated user model
diff --git a/datatypes/eval.html b/datatypes/eval.html
index 10880a6b66..6801f3eaa5 100644
--- a/datatypes/eval.html
+++ b/datatypes/eval.html
@@ -257,7 +257,7 @@ 
println("Running expensive calculation...")
   1 + 2 * 3
 }
-// lazyEval: Eval[Int] = cats.Later@5820f16e
+// lazyEval: Eval[Int] = cats.Later@3dc53ebc
 
 lazyEval.value
 // Running expensive calculation...
@@ -276,7 +276,7 @@ 
println("Running expensive calculation...")
   1 + 2 * 3
 }
-// always: Eval[Int] = cats.Always@2c752c5a
+// always: Eval[Int] = cats.Always@4975ff1e
 
 always.value
 // Running expensive calculation...
diff --git a/datatypes/freeapplicative.html b/datatypes/freeapplicative.html
index c5482658a7..3fd9b3375c 100644
--- a/datatypes/freeapplicative.html
+++ b/datatypes/freeapplicative.html
@@ -275,7 +275,7 @@ 
val validator = prog.foldMap[FromString](compiler)
-// validator: FromString[Boolean] = cats.instances.Function1Instances$$anon$7$$Lambda$12108/0x00007f9d0a8aaa80@1096d467
+// validator: FromString[Boolean] = cats.instances.Function1Instances$$anon$7$$Lambda$14501/0x00007f95666fa000@640d2b0
 validator("1234")
 // res0: Boolean = false
 validator("12345")
diff --git a/datatypes/freemonad.html b/datatypes/freemonad.html
index 0e07995c24..ef7b0ff31e 100644
--- a/datatypes/freemonad.html
+++ b/datatypes/freemonad.html
@@ -718,7 +718,7 @@ 
import TeletypeOps._
 
 val state = program.foldMap(interpreter)
-// state: TeletypeState[Unit] = cats.data.IndexedStateT@45fa4f2c
+// state: TeletypeState[Unit] = cats.data.IndexedStateT@7c94c66
 val initialState = Nil
 // initialState: Nil.type = List()
 val (stored, _) = state.run(initialState).value
@@ -789,7 +789,7 @@ 
val evaluated = hoisted.foldMap(tryInterpreter)
 // evaluated: OptTry[Int] = OptionT(value = Success(value = Some(value = 12)))
diff --git a/datatypes/state.html b/datatypes/state.html
index b271df9585..0bf4953d1d 100644
--- a/datatypes/state.html
+++ b/datatypes/state.html
@@ -474,7 +474,7 @@ 
_ <- close
   _ <- open
 } yield ()
-// valid: IndexedStateT[Eval, Closed.type, Open.type, Unit] = cats.data.IndexedStateT@5d142bb1
+// valid: IndexedStateT[Eval, Closed.type, Open.type, Unit] = cats.data.IndexedStateT@4998e199

Note that the inferred type of valid correctly models that this computation can be executed only with an initial Closed state.

valid.run(Open)
 // error: type mismatch;
@@ -483,7 +483,7 @@ 
valid.run(Closed)
-// res6: Eval[(Open.type, Unit)] = cats.Eval$$anon$1@122681b6
+// res6: Eval[(Open.type, Unit)] = cats.Eval$$anon$1@7a103ba8
diff --git a/typeclasses/bifoldable.html b/typeclasses/bifoldable.html index 98f23adc87..cc0e6550e3 100644 --- a/typeclasses/bifoldable.html +++ b/typeclasses/bifoldable.html @@ -338,7 +338,7 @@

s, acc) => acc.map(_ |+| s), (s, acc) => acc.map(_ |+| s) ) -// right: Eval[String] = cats.Eval$$anon$1@6ba69df7 +// right: Eval[String] = cats.Eval$$anon$1@59d5c12 left === expected // res2: Boolean = true @@ -354,7 +354,7 @@

s, acc) => acc.map(_ |+| s), (s, acc) => acc.map(_ |+| s) ) -// reversedRight: Eval[String] = cats.Eval$$anon$1@55476083 +// reversedRight: Eval[String] = cats.Eval$$anon$1@5d602a4b reversedRight.value === expected // res4: Boolean = false diff --git a/typeclasses/bifunctor.html b/typeclasses/bifunctor.html index d504a7f3ec..265f6d2fa9 100644 --- a/typeclasses/bifunctor.html +++ b/typeclasses/bifunctor.html @@ -246,7 +246,7 @@

error => DomainError(error.getMessage), dateTime => dateTime.toEpochSecond ) -// res0: Either[DomainError, Long] = Right(value = 1737195652L) +// res0: Either[DomainError, Long] = Right(value = 1737231470L)

Bifunctor also defines a convenience function called leftMap, which is defined as follows:

def leftMap[A, B, C](fab: F[A, B])(f: A => C): F[C, B] = bimap(fab)(f, identity)

There is no rightMap however - use map instead. The reasoning behind this is that in Cats, the instances of diff --git a/typeclasses/bimonad.html b/typeclasses/bimonad.html index bc8161bb6e..eb8cf477da 100644 --- a/typeclasses/bimonad.html +++ b/typeclasses/bimonad.html @@ -263,7 +263,7 @@

override def tailRecM[A, B](a: A)(fn: A => NonEmptyList[Either[A, B]]): NonEmptyList[B] = ??? } -// nelBimonad: Bimonad[NonEmptyList] = repl.MdocSession$MdocApp$$anon$1@7a407065 +// nelBimonad: Bimonad[NonEmptyList] = repl.MdocSession$MdocApp$$anon$1@4a2df027

Note the equivalence:

nelBimonad.pure(true).extract === NonEmptyList.one(true).head
 // res0: Boolean = true
diff --git a/typeclasses/contravariant.html b/typeclasses/contravariant.html index 1e186c12d7..14787a71f7 100644 --- a/typeclasses/contravariant.html +++ b/typeclasses/contravariant.html @@ -246,7 +246,7 @@

implicit val showSalary: Show[Salary] = showMoney.contramap(_.size) -// showSalary: Show[Salary] = cats.Show$$anon$2$$Lambda$12920/0x00007f9d0b2da5b0@4953b4a1 +// showSalary: Show[Salary] = cats.Show$$anon$2$$Lambda$15313/0x00007f956699fd60@20895ff4 Salary(Money(1000)).show // res0: String = "$1000" @@ -266,7 +266,7 @@

import scala.math.Ordered._ implicit val moneyOrdering: Ordering[Money] = Ordering.by(_.amount) -// moneyOrdering: Ordering[Money] = scala.math.Ordering$$anon$5@2e8bd690 +// moneyOrdering: Ordering[Money] = scala.math.Ordering$$anon$5@a5ea56 Money(100) < Money(200) // res3: Boolean = true @@ -276,17 +276,17 @@

class A class B extends A val b: B = new B -// b: B = repl.MdocSession$MdocApp$B@341363ea +// b: B = repl.MdocSession$MdocApp$B@17780bae val a: A = b -// a: A = repl.MdocSession$MdocApp$B@341363ea +// a: A = repl.MdocSession$MdocApp$B@17780bae val showA: Show[A] = Show.show(a => "a!") -// showA: Show[A] = cats.Show$$$Lambda$12919/0x00007f9d0b2da138@3f7a9f25 +// showA: Show[A] = cats.Show$$$Lambda$15312/0x00007f956699f8e8@7d09de0f val showB1: Show[B] = showA.contramap(b => b: A) -// showB1: Show[B] = cats.Show$$anon$2$$Lambda$12920/0x00007f9d0b2da5b0@e2e729d +// showB1: Show[B] = cats.Show$$anon$2$$Lambda$15313/0x00007f956699fd60@1291229a val showB2: Show[B] = showA.contramap(identity[A]) -// showB2: Show[B] = cats.Show$$anon$2$$Lambda$12920/0x00007f9d0b2da5b0@e7ded01 +// showB2: Show[B] = cats.Show$$anon$2$$Lambda$15313/0x00007f956699fd60@10597c08 val showB3: Show[B] = Contravariant[Show].narrow[A, B](showA) -// showB3: Show[B] = cats.Show$$$Lambda$12919/0x00007f9d0b2da138@3f7a9f25 +// showB3: Show[B] = cats.Show$$$Lambda$15312/0x00007f956699f8e8@7d09de0f

Subtyping relationships are "lifted backwards" by contravariant functors, such that if F is a lawful contravariant functor and B <: A then F[A] <: F[B], which is expressed by Contravariant.narrow.

diff --git a/typeclasses/eq.html b/typeclasses/eq.html index 00e15306da..faa621c7e4 100644 --- a/typeclasses/eq.html +++ b/typeclasses/eq.html @@ -257,7 +257,7 @@

Eq

implicit val eqFoo: Eq[Foo] = Eq.fromUniversalEquals -// eqFoo: Eq[Foo] = cats.kernel.Eq$$anonfun$fromUniversalEquals$2@47942242 +// eqFoo: Eq[Foo] = cats.kernel.Eq$$anonfun$fromUniversalEquals$2@3de57771 Foo(10, "") === Foo(10, "") diff --git a/typeclasses/semigroup.html b/typeclasses/semigroup.html index 1e1342af50..d81b1d10c4 100644 --- a/typeclasses/semigroup.html +++ b/typeclasses/semigroup.html @@ -269,23 +269,23 @@

import cats.Semigroup import cats.syntax.all._ 
Semigroup[Int]
-// res8: Semigroup[Int] = cats.kernel.instances.IntGroup@993450a
+// res8: Semigroup[Int] = cats.kernel.instances.IntGroup@1e97cd49
 Semigroup[String]
-// res9: Semigroup[String] = cats.kernel.instances.StringMonoid@6fc06bfc
+// res9: Semigroup[String] = cats.kernel.instances.StringMonoid@7329798d

Instances for type constructors regardless of their type parameter such as List (++) and Set (union)...

Semigroup[List[Byte]]
-// res10: Semigroup[List[Byte]] = cats.kernel.instances.ListMonoid@58ce0459
+// res10: Semigroup[List[Byte]] = cats.kernel.instances.ListMonoid@4f5d9817
 Semigroup[Set[Int]]
-// res11: Semigroup[Set[Int]] = cats.kernel.instances.SetSemilattice@b1f3e36
+// res11: Semigroup[Set[Int]] = cats.kernel.instances.SetSemilattice@70ad8b92
 
 trait Foo
 Semigroup[List[Foo]]
-// res12: Semigroup[List[Foo]] = cats.kernel.instances.ListMonoid@58ce0459
+// res12: Semigroup[List[Foo]] = cats.kernel.instances.ListMonoid@4f5d9817

And instances for type constructors that depend on (one of) their type parameters having instances such as tuples (pointwise combine).

Semigroup[(List[Foo], Int)]
-// res13: Semigroup[(List[Foo], Int)] = cats.kernel.Monoid$$anon$2@18b7914a
+// res13: Semigroup[(List[Foo], Int)] = cats.kernel.Monoid$$anon$2@50f0ed4b

Example usage: Merging maps

Consider a function that merges two Maps that combines values if they share diff --git a/typeclasses/show.html b/typeclasses/show.html index b30748f9e6..581335f655 100644 --- a/typeclasses/show.html +++ b/typeclasses/show.html @@ -229,7 +229,7 @@

Show

Most often, this is unwanted behaviour, as the standard implementation of toString on non case classes is mostly gibberish. Consider the following example:

(new {}).toString
-// res0: String = "repl.MdocSession$MdocApp$$anon$1@27266542"
+// res0: String = "repl.MdocSession$MdocApp$$anon$1@2f09671e"

The fact that this code compiles is a design flaw of the Java API. We want to make things like this impossible, by offering the toString equivalent as a type class, instead of the root of the class hierarchy. In short, Show allows us to only have String-conversions defined for the data types we actually want.

@@ -245,12 +245,12 @@

Show

case class Person(name: String, age: Int) implicit val showPerson: Show[Person] = Show.show(person => person.name) -// showPerson: Show[Person] = cats.Show$$$Lambda$12919/0x00007f9d0b2da138@3f56d22a +// showPerson: Show[Person] = cats.Show$$$Lambda$15312/0x00007f956699f8e8@47340fc8 case class Department(id: Int, name: String) implicit val showDep: Show[Department] = Show.fromToString -// showDep: Show[Department] = cats.Show$$$Lambda$11932/0x00007f9d0aff5ca8@538c5e04 +// showDep: Show[Department] = cats.Show$$$Lambda$14325/0x00007f9566641cd0@5bab7278

This still may not seem useful to you, because case classes already automatically implement toString, while show would have to be implemented manually for each case class. Thankfully with the help of a small library called kittens a lot of type class instances including Show can be derived automatically!

Cats also offers Show syntax to make working with it easier.