meanwhile you can use an epimorphism to lift any `...

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[tschuchort]

meanwhile you can use an epimorphism to lift any Killer -> A function to a Test -> A function but it's somewhat annoying to use

[b8b]

Do you mean that? https://discuss.kotlinlang.org/t/typeclass-kclass/6760

[b8b]

I'd need more time to understand it.

[tschuchort]

keep 87: https://github.com/Kotlin/KEEP/pull/87

[tschuchort]

typeclasses are something like static interfaces and you can have multiple implementations of a typeclass for a type

[b8b]

thx. that's an interesting topic

[tschuchort]

for example consider an interface Monoid for something that can be empty and combined:

typeclass Monoid<M> {
     fun empty(): M
     fun combine(a: M, b: M): M
}

Int can implement this in two ways. Either with 0 and `+`:

instance Monoid<Int> {
    fun empty() = 0
    fun combine(a: Int, b: Int) = a + b

or with 1 and `*`:

instance Monoid<Int> {
    fun empty() = 1
    fun combine(a: Int, b: Int) = a * b

[tschuchort]

in this case there are also some laws for monoids:
for all a: combine(a, empty()) == a