Skip to content

Commit

Permalink
Use instance constructors instead of SAM types
Browse files Browse the repository at this point in the history 
Due to limitations in Scala 2 SAM types often end up generating
classes after all. `instance` constructors don't suffer from this
issue and also let us handle type classes with multiple abstract
methods.
  • Loading branch information
@joroKr21
joroKr21 committed Apr 27, 2021
1 parent a03f973 commit 1671eb7
Show file tree
Hide file tree
Showing 4 changed files with 97 additions and 87 deletions.
10 changes: 10 additions & 0 deletions kernel/src/main/scala/cats/kernel/CommutativeGroup.scala
View file
Original file line number Diff line number Diff line change
Expand Up @@ -14,4 +14,14 @@ object CommutativeGroup extends GroupFunctions[CommutativeGroup] {
* Access an implicit `CommutativeGroup[A]`.
*/
@inline final def apply[A](implicit ev: CommutativeGroup[A]): CommutativeGroup[A] = ev

/**
* Create a `CommutativeGroup` instance from the given inverse and combine functions and empty value.
*/
@inline def instance[A](emp: A, inv: A => A, cmb: (A, A) => A): CommutativeGroup[A] =
new CommutativeGroup[A] {
val empty = emp
def inverse(a: A) = inv(a)
def combine(x: A, y: A) = cmb(x, y)
}
}
10 changes: 10 additions & 0 deletions kernel/src/main/scala/cats/kernel/Group.scala
View file
Original file line number Diff line number Diff line change
Expand Up @@ -74,4 +74,14 @@ object Group extends GroupFunctions[Group] {
* Access an implicit `Group[A]`.
*/
@inline final def apply[A](implicit ev: Group[A]): Group[A] = ev

/**
* Create a `Group` instance from the given inverse and combine functions and empty value.
*/
@inline def instance[A](emp: A, inv: A => A, cmb: (A, A) => A): Group[A] =
new Group[A] {
val empty = emp
def inverse(a: A) = inv(a)
def combine(x: A, y: A) = cmb(x, y)
}
}
12 changes: 9 additions & 3 deletions kernel/src/main/scala/cats/kernel/Hash.scala
View file
Original file line number Diff line number Diff line change
Expand Up @@ -54,11 +54,17 @@ object Hash extends HashFunctions[Hash] {
def eqv(x: A, y: A) = x == y
}

/**
* Create a `Hash` instance from the given hash and equality functions.
*/
@inline def instance[A](h: A => Int, e: (A, A) => Boolean): Hash[A] =
new Hash[A] {
def hash(x: A) = h(x)
def eqv(x: A, y: A) = e(x, y)
}
}

trait HashToHashingConversion {
implicit def catsKernelHashToHashing[A](implicit ev: Hash[A]): Hashing[A] =
new Hashing[A] {
override def hash(x: A): Int = ev.hash(x)
}
ev.hash(_)
}
152 changes: 68 additions & 84 deletions project/KernelBoiler.scala
View file
Original file line number Diff line number Diff line change
Expand Up @@ -143,21 +143,17 @@ object KernelBoiler {
block"""
| implicit def catsKernelStdCommutativeGroupForTuple$arity[${`A..N`}](
| implicit ${constraints("CommutativeGroup")}
| ): CommutativeGroup[${`(A..N)`}] = new CommutativeGroup[${`(A..N)`}] {
| def combine(x: ${`(A..N)`}, y: ${`(A..N)`}): ${`(A..N)`} = ${binTuple("combine")}
| def empty: ${`(A..N)`} = ${nullaryTuple("empty")}
| def inverse(x: ${`(A..N)`}): ${`(A..N)`} = ${unaryTuple("inverse")}
| }
| ): CommutativeGroup[${`(A..N)`}] =
| Semigroup.catsKernelCommutativeGroupForTuple$arity[${`A..N`}]
| implicit def catsKernelStdOrderForTuple$arity[${`A..N`}](
| implicit ${constraints("Order")}
| ): Order[${`(A..N)`}] = (x, y) =>
| ${binMethod("compare").mkString("Array(", ", ", ")")}.find(_ != 0).getOrElse(0)
| ): Order[${`(A..N)`}] =
| Eq.catsKernelOrderForTuple$arity[${`A..N`}]
| implicit def catsKernelStdBoundedSemilatticeForTuple$arity[${`A..N`}](
| implicit ${constraints("BoundedSemilattice")}
| ): BoundedSemilattice[${`(A..N)`}] = new BoundedSemilattice[${`(A..N)`}] {
| def combine(x: ${`(A..N)`}, y: ${`(A..N)`}): ${`(A..N)`} = ${binTuple("combine")}
| def empty: ${`(A..N)`} = ${nullaryTuple("empty")}
| }"""
| ): BoundedSemilattice[${`(A..N)`}] =
| Semigroup.catsKernelBoundedSemilatticeForTuple$arity[${`A..N`}]
|"""
}
),
InstanceDef(
Expand All @@ -170,33 +166,24 @@ object KernelBoiler {
block"""
| implicit def catsKernelStdSemilatticeForTuple$arity[${`A..N`}](
| implicit ${constraints("Semilattice")}
| ): Semilattice[${`(A..N)`}] = (x, y) =>
| ${binTuple("combine")}
| ): Semilattice[${`(A..N)`}] =
| Semigroup.catsKernelSemilatticeForTuple$arity[${`A..N`}]
| implicit def catsKernelStdCommutativeMonoidForTuple$arity[${`A..N`}](
| implicit ${constraints("CommutativeMonoid")}
| ): CommutativeMonoid[${`(A..N)`}] = new CommutativeMonoid[${`(A..N)`}] {
| def combine(x: ${`(A..N)`}, y: ${`(A..N)`}): ${`(A..N)`} = ${binTuple("combine")}
| def empty: ${`(A..N)`} = ${nullaryTuple("empty")}
| }
| ): CommutativeMonoid[${`(A..N)`}] =
| Semigroup.catsKernelCommutativeMonoidForTuple$arity[${`A..N`}]
| implicit def catsKernelStdGroupForTuple$arity[${`A..N`}](
| implicit ${constraints("Group")}
| ): Group[${`(A..N)`}] = new Group[${`(A..N)`}] {
| def combine(x: ${`(A..N)`}, y: ${`(A..N)`}): ${`(A..N)`} = ${binTuple("combine")}
| def empty: ${`(A..N)`} = ${nullaryTuple("empty")}
| def inverse(x: ${`(A..N)`}): ${`(A..N)`} = ${unaryTuple("inverse")}
| }
| ): Group[${`(A..N)`}] =
| Semigroup.catsKernelGroupForTuple$arity[${`A..N`}]
| implicit def catsKernelStdHashForTuple$arity[${`A..N`}](
| implicit ${constraints("Hash")}
| ): Hash[${`(A..N)`}] = new Hash[${`(A..N)`}] {
| def hash(x: ${`(A..N)`}): Int =
| ${unaryMethod("hash").mkString(s"$tupleNHeader(", ", ", ")")}.hashCode()
| def eqv(x: ${`(A..N)`}, y: ${`(A..N)`}): Boolean =
| ${binMethod("eqv").mkString(" && ")}
| }
| ): Hash[${`(A..N)`}] =
| Eq.catsKernelHashForTuple$arity[${`A..N`}]
| implicit def catsKernelStdPartialOrderForTuple$arity[${`A..N`}](
| implicit ${constraints("PartialOrder")}
| ): PartialOrder[${`(A..N)`}] = (x, y) =>
| ${binMethod("partialCompare").mkString("Array(", ", ", ")")}.find(_ != 0.0).getOrElse(0.0)
| ): PartialOrder[${`(A..N)`}] =
| Eq.catsKernelPartialOrderForTuple$arity[${`A..N`}]
|"""
}
),
Expand All @@ -210,18 +197,17 @@ object KernelBoiler {
block"""
| implicit def catsKernelStdBandForTuple$arity[${`A..N`}](
| implicit ${constraints("Band")}
| ): Band[${`(A..N)`}] = (x, y) =>
| ${binTuple("combine")}
| ): Band[${`(A..N)`}] =
| Semigroup.catsKernelBandForTuple$arity[${`A..N`}]
| implicit def catsKernelStdCommutativeSemigroupForTuple$arity[${`A..N`}](
| implicit ${constraints("CommutativeSemigroup")}
| ): CommutativeSemigroup[${`(A..N)`}] = (x, y) =>
| ${binTuple("combine")}
| ): CommutativeSemigroup[${`(A..N)`}] =
| Semigroup.catsKernelCommutativeSemigroupForTuple$arity[${`A..N`}]
| implicit def catsKernelStdMonoidForTuple$arity[${`A..N`}](
| implicit ${constraints("Monoid")}
| ): Monoid[${`(A..N)`}] = new Monoid[${`(A..N)`}] {
| def combine(x: ${`(A..N)`}, y: ${`(A..N)`}): ${`(A..N)`} = ${binTuple("combine")}
| def empty: ${`(A..N)`} = ${nullaryTuple("empty")}
| }"""
| ): Monoid[${`(A..N)`}] =
| Semigroup.catsKernelMonoidForTuple$arity[${`A..N`}]
|"""
}
),
InstanceDef(
Expand All @@ -234,12 +220,12 @@ object KernelBoiler {
block"""
| implicit def catsKernelStdSemigroupForTuple$arity[${`A..N`}](
| implicit ${constraints("Semigroup")}
| ): Semigroup[${`(A..N)`}] = (x, y) =>
| ${binTuple("combine")}
| ): Semigroup[${`(A..N)`}] =
| Semigroup.catsKernelSemigroupForTuple$arity[${`A..N`}]
| implicit def catsKernelStdEqForTuple$arity[${`A..N`}](
| implicit ${constraints("Eq")}
| ): Eq[${`(A..N)`}] = (x, y) =>
| ${binMethod("eqv").mkString(" && ")}
| ): Eq[${`(A..N)`}] =
| Eq.catsKernelEqForTuple$arity[${`A..N`}]
|"""
}
),
Expand All @@ -252,9 +238,9 @@ object KernelBoiler {
block"""
| implicit def catsKernelBandForTuple$arity[${`A..N`}](
| implicit ${constraints("Band")}
| ): Band[${`(A..N)`}] = (x, y) =>
| ): Band[${`(A..N)`}] = Band.instance { (x, y) =>
| ${binTuple("combine")}
|"""
| }"""
}
),
InstanceDef(
Expand All @@ -266,10 +252,10 @@ object KernelBoiler {
block"""
| implicit def catsKernelBoundedSemilatticeForTuple$arity[${`A..N`}](
| implicit ${constraints("BoundedSemilattice")}
| ): BoundedSemilattice[${`(A..N)`}] = new BoundedSemilattice[${`(A..N)`}] {
| def combine(x: ${`(A..N)`}, y: ${`(A..N)`}): ${`(A..N)`} = ${binTuple("combine")}
| def empty: ${`(A..N)`} = ${nullaryTuple("empty")}
| }"""
| ): BoundedSemilattice[${`(A..N)`}] = BoundedSemilattice.instance(
| ${nullaryTuple("empty")},
| (x, y) => ${binTuple("combine")}
| )"""
}
),
InstanceDef(
Expand All @@ -281,11 +267,11 @@ object KernelBoiler {
block"""
| implicit def catsKernelCommutativeGroupForTuple$arity[${`A..N`}](
| implicit ${constraints("CommutativeGroup")}
| ): CommutativeGroup[${`(A..N)`}] = new CommutativeGroup[${`(A..N)`}] {
| def combine(x: ${`(A..N)`}, y: ${`(A..N)`}): ${`(A..N)`} = ${binTuple("combine")}
| def empty: ${`(A..N)`} = ${nullaryTuple("empty")}
| def inverse(x: ${`(A..N)`}): ${`(A..N)`} = ${unaryTuple("inverse")}
| }"""
| ): CommutativeGroup[${`(A..N)`}] = CommutativeGroup.instance(
| ${nullaryTuple("empty")},
| x => ${unaryTuple("inverse")},
| (x, y) => ${binTuple("combine")}
| )"""
}
),
InstanceDef(
Expand All @@ -297,10 +283,10 @@ object KernelBoiler {
block"""
| implicit def catsKernelCommutativeMonoidForTuple$arity[${`A..N`}](
| implicit ${constraints("CommutativeMonoid")}
| ): CommutativeMonoid[${`(A..N)`}] = new CommutativeMonoid[${`(A..N)`}] {
| def combine(x: ${`(A..N)`}, y: ${`(A..N)`}): ${`(A..N)`} = ${binTuple("combine")}
| def empty: ${`(A..N)`} = ${nullaryTuple("empty")}
| }"""
| ): CommutativeMonoid[${`(A..N)`}] = CommutativeMonoid.instance(
| ${nullaryTuple("empty")},
| (x, y) => ${binTuple("combine")}
| )"""
}
),
InstanceDef(
Expand All @@ -312,9 +298,9 @@ object KernelBoiler {
block"""
| implicit def catsKernelCommutativeSemigroupForTuple$arity[${`A..N`}](
| implicit ${constraints("CommutativeSemigroup")}
| ): CommutativeSemigroup[${`(A..N)`}] = (x, y) =>
| ): CommutativeSemigroup[${`(A..N)`}] = CommutativeSemigroup.instance { (x, y) =>
| ${binTuple("combine")}
|"""
| }"""
}
),
InstanceDef(
Expand All @@ -326,9 +312,9 @@ object KernelBoiler {
block"""
| implicit def catsKernelEqForTuple$arity[${`A..N`}](
| implicit ${constraints("Eq")}
| ): Eq[${`(A..N)`}] = (x, y) =>
| ): Eq[${`(A..N)`}] = Eq.instance { (x, y) =>
| ${binMethod("eqv").mkString(" && ")}
|"""
| }"""
}
),
InstanceDef(
Expand All @@ -340,11 +326,11 @@ object KernelBoiler {
block"""
| implicit def catsKernelGroupForTuple$arity[${`A..N`}](
| implicit ${constraints("Group")}
| ): Group[${`(A..N)`}] = new Group[${`(A..N)`}] {
| def combine(x: ${`(A..N)`}, y: ${`(A..N)`}): ${`(A..N)`} = ${binTuple("combine")}
| def empty: ${`(A..N)`} = ${nullaryTuple("empty")}
| def inverse(x: ${`(A..N)`}): ${`(A..N)`} = ${unaryTuple("inverse")}
| }"""
| ): Group[${`(A..N)`}] = Group.instance(
| ${nullaryTuple("empty")},
| x => ${unaryTuple("inverse")},
| (x, y) => ${binTuple("combine")}
| )"""
}
),
InstanceDef(
Expand All @@ -356,12 +342,10 @@ object KernelBoiler {
block"""
| implicit def catsKernelHashForTuple$arity[${`A..N`}](
| implicit ${constraints("Hash")}
| ): Hash[${`(A..N)`}] = new Hash[${`(A..N)`}] {
| def hash(x: ${`(A..N)`}): Int =
| ${unaryMethod("hash").mkString(s"$tupleNHeader(", ", ", ")")}.hashCode()
| def eqv(x: ${`(A..N)`}, y: ${`(A..N)`}): Boolean =
| ${binMethod("eqv").mkString(" && ")}
| }"""
| ): Hash[${`(A..N)`}] = Hash.instance(
| x => ${unaryMethod("hash").mkString(s"$tupleNHeader(", ", ", ")")}.hashCode(),
| (x, y) => ${binMethod("eqv").mkString(" && ")}
| )"""
}
),
InstanceDef(
Expand All @@ -373,10 +357,10 @@ object KernelBoiler {
block"""
| implicit def catsKernelMonoidForTuple$arity[${`A..N`}](
| implicit ${constraints("Monoid")}
| ): Monoid[${`(A..N)`}] = new Monoid[${`(A..N)`}] {
| def combine(x: ${`(A..N)`}, y: ${`(A..N)`}): ${`(A..N)`} = ${binTuple("combine")}
| def empty: ${`(A..N)`} = ${nullaryTuple("empty")}
| }"""
| ): Monoid[${`(A..N)`}] = Monoid.instance(
| ${nullaryTuple("empty")},
| (x, y) => ${binTuple("combine")}
| )"""
}
),
InstanceDef(
Expand All @@ -388,9 +372,9 @@ object KernelBoiler {
block"""
| implicit def catsKernelOrderForTuple$arity[${`A..N`}](
| implicit ${constraints("Order")}
| ): Order[${`(A..N)`}] = (x, y) =>
| ): Order[${`(A..N)`}] = Order.from { (x, y) =>
| ${binMethod("compare").mkString("Array(", ", ", ")")}.find(_ != 0).getOrElse(0)
|"""
| }"""
}
),
InstanceDef(
Expand All @@ -402,9 +386,9 @@ object KernelBoiler {
block"""
| implicit def catsKernelPartialOrderForTuple$arity[${`A..N`}](
| implicit ${constraints("PartialOrder")}
| ): PartialOrder[${`(A..N)`}] = (x, y) =>
| ): PartialOrder[${`(A..N)`}] = PartialOrder.from { (x, y) =>
| ${binMethod("partialCompare").mkString("Array(", ", ", ")")}.find(_ != 0.0).getOrElse(0.0)
|"""
| }"""
}
),
InstanceDef(
Expand All @@ -416,9 +400,9 @@ object KernelBoiler {
block"""
| implicit def catsKernelSemigroupForTuple$arity[${`A..N`}](
| implicit ${constraints("Semigroup")}
| ): Semigroup[${`(A..N)`}] = (x, y) =>
| ): Semigroup[${`(A..N)`}] = Semigroup.instance { (x, y) =>
| ${binTuple("combine")}
|"""
| }"""
}
),
InstanceDef(
Expand All @@ -430,9 +414,9 @@ object KernelBoiler {
block"""
| implicit def catsKernelSemilatticeForTuple$arity[${`A..N`}](
| implicit ${constraints("Semilattice")}
| ): Semilattice[${`(A..N)`}] = (x, y) =>
| ): Semilattice[${`(A..N)`}] = Semilattice.instance { (x, y) =>
| ${binTuple("combine")}
|"""
| }"""
}
)
)
Expand Down

0 comments on commit 1671eb7

Please sign in to comment.