Kotlin DSL & Builder Patterns — apply, buildList & Custom DSLs

Kotlin DSLs & Builder Patterns Kotlin's scope functions and receiver lambdas enable elegant DSL patterns. Learn apply , buildList , and create custom DSLs. apply for Object Initialization The apply function returns the object after configuring it: val user = User ( "Alice" ). apply { age = 30 email = "alice@example.com" isActive = true } Much cleaner than: val user = User ( "Alice" ) user . age = 30 user . email = "alice@example.com" buildList & buildMap Create collections with conditional items: val features = buildList { add ( "Login" ) add ( "Profile" ) if ( isAdmin ) add ( "Admin Panel" ) if ( isPremium ) addAll ( listOf ( "Analytics" , "Export" )) } val config = buildMap { put ( "version" , "1.0" ) put ( "debug" , isDebugBuild ) if ( useCache ) put ( "cache_ttl" , 3600 ) } Custom DSL with Receiver Lambdas Create a UI builder DSL: class HtmlBuilder { private val children = mutableListOf < String >() fun p ( text : String ) { children . add ( "<p>$text</p>" ) } fun h1 ( text : Strin