Have you heard about inline classes in Kotlin?

InlineClasses.kt

// Why use inline classes? 🤔 
// 🎯 Compile time safety 
// 🎯 Less runtime overhead than a normal wrapper class as it "inlines" the data into its usages   
// More info : https://kotlinlang.org/docs/reference/inline-classes.html


// Without inline classes 😞
data class Recipe(id: UUID)

data class Ingredient(id: UUID, recipeId: UUID)

val recipeId = UUID.randomUUID()

val incorrectIngredient = Ingredient(recipeId, recipeId) // compiles perfectly - but incorrect ID 😨


// With inline classes ✅
inline class RecipeId(id: UUID)
inline class IngredientId(id: UUID)

data class Recipe(id: RecipeId)

data class Ingredient(id: IngredientId, recipeId: RecipeId)

val ingredientId = IngredientId(UUID.randomUUID())
// Can be quite easy to pass in the incorrect UUID without inline classes:
val doesntCompileIngredient = Ingredient(ingredientId, ingredientId) // wont compile! yay! 🎈

val recipeId = RecipeId(UUID.randomUUID())
val safeCompilingIngredient = Ingredient(ingredientId, recipeId) // compiles and is safer! 🔐

// NOTE: Inline classes are still an experimental feature 
// Use with caution 🧪