elizarov

// Aspect interface for combinator
interface Aspect {
    operator fun <R> invoke(block: () -> R): R
}

// Aspect combinator
operator fun Aspect.plus(other: Aspect) = object : Aspect {
    override fun <R> invoke(block: () -> R): R =
        this@plus {
            other {

norswap

// Basic setup

interface Exp
data class Lit(val x: Int): Exp
data class Add(val x: Exp, val y: Exp): Exp

interface IntAlg<A>
{
    fun lit(x: Int): A
    fun add(x: A, y: A): A