Kotlin Functions Lambda Functions


Lambda functions are anonymous functions which are usually created during a function call to act as a function parameter. They are declared by surrounding expressions with {braces} - if arguments are needed, these are put before an arrow ->.

{ name: String ->
    "Your name is $name" //This is returned

The last statement inside a lambda function is automatically the return value.

The type's are optional, if you put the lambda on a place where the compiler can infer the types.

Multiple arguments:

{ argumentOne:String, argumentTwo:String ->
    "$argumentOne - $argumentTwo"

If the lambda function only needs one argument, then the argument list can be omitted and the single argument be referred to using it instead.

{ "Your name is $it" }

If the only argument to a function is a lambda function, then parentheses can be completely omitted from the function call.

# These are identical
listOf(1, 2, 3, 4).map { it + 2 }
listOf(1, 2, 3, 4).map({ it + 2 })