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scalascala-cats

Cats typeclass for isomorphic types

What cats typeclass should I use to encode that two types are Isomorphic (i.e. can be converted back and forth without effects)

I want to encode the decomposition of a type into a tuple of two others: A <=> (B, C)

Obviously, the typeclass should expose the two functions for each direction of the conversion, and ideally implicit methods for convenient conversion. Something like this: (but failed to find it)

trait Iso[A,B] {
  def to(a: A):B
  def from(b: B): A
}
Solution

  • Are you looking for cats.evidence.Is?

    type A
type B

type X = Is[A, B] // A Is B

val a: A = ???
val b: B = ???
val x: A Is B = ???
val y: B Is A = ???

x.coerce(a): B
y.coerce(b): A

    It's similar to scalaz.Leibniz.