Kotlin 中默認參數后面的閉包作為參數

Question

我有一個功能

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

其中 ResponseResolver 是類型別名

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

當我調用如下 get 方法時：

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

然后 Intellij 告訴我

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>
)

我不確定將閉包用作某些具有默認參數的函數的參數是否有任何限制。

Answer 1

Kotlin 並不確切知道mutableMapOf("key" to "value")是什么。

明確是參數還是標題

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

或者

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