Kotlin 中默认参数后面的闭包作为参数

Question

I have a function

fun <T> get(path: String, params: MutableMap<String, Any>? = null, headers: MutableMap<String, String>? = null, resolver: ResponseResolver<T>): HttpRequest<T>

which ResponseResolver is a type alias

typealias ResponseResolver<T> = (HttpResponse) -> T

When i invoke the get method like below:

get("/somePath", mutableMapOf("key" to "value")){ httpResponse -> ......some code(Last line is a List<SomeClass>)

Then the Intellij tells me that

Type inference failed: 

fun <T> get
(
path: String,
params: MutableMap<String, Any>? = ...,
headers: MutableMap<String, String>? = ...,
resolver: ResponseResolver<T> /* = (HttpResponse) → T */
)
: HttpRequest<T>

cannot be applied to
(
String,
MutableMap<String, Any>,
(HttpResponse) → List<SomeClass>
)

I'm not sure if there is any strictions in applying the closure as the argument of some functions with default parameters.

Answer 1

Kotlin don't know exactly what mutableMapOf("key" to "value") is.

Clarify whether it's params or headers

get("/somePath", headers = mutableMapOf("key" to "value")){ httpResponse -> ......some code(Last line is a List<SomeClass>)

or

get("/somePath", mutableMapOf<String, Any>("key" to "value")){ httpResponse -> ......some code(Last line is a List<SomeClass>)