我正在尝试使用Clojure manifold
库,为了理解它,我需要将core.async
通道转换为流形流。
我想使用core.async
通道创建等效的以下内容:
(require '[manifold.stream :as s])
(s/periodically 100 #(str " ok "))
;; Here is what I tried, it fails with an error 500
(let [ch (chan)]
(go-loop []
(>! ch " ok ")
(<! (timeout 100))
(recur))
(s/->source ch))
我正在尝试将core.async
信道馈送到yada
。使用manifold.stream/periodic
的第一个代码示例有效,而其他使用core.async
的代码示例无效。我试过雅达1.0.0
和1.1.0-SNAPSHOT
。
使用manifold.stream/periodic
作品:
(def get-stream
(yada (fn [ctx]
(-> (:response ctx)
(assoc :status 202)
(assoc :body (s/periodically 1000 #(str (System/currentTimeMillis) " ")))))
{:representations [{:media-type "application/json"
:charset "UTF-8"}
{:media-type "application/edn"
:charset "UTF-8"}]}))
使用manifold.stream/->source
返回错误500:
(def get-stream
(yada (fn [ctx]
(-> (:response ctx)
(assoc :status 202)
;; Similar to this : https://github.com/juxt/yada/blob/94f3ee93de155a8513b27e0508608691ed556a55/dev/src/yada/dev/async.clj
(assoc :body (let [ch (chan)]
(go-loop []
(>! ch " ok ")
(<! (timeout 100))
(recur))
(s/->source ch)))))
{:representations [{:media-type "application/json"
:charset "UTF-8"}
{:media-type "application/edn"
:charset "UTF-8"}]}))
;; Error on the page :
;; 500: Unknown
;; Error on GET
;; #error {
;; :cause "No implementation of method: :to-body of protocol: #'yada.body/MessageBody found for class: manifold.stream.async.CoreAsyncSource"
;; :via
;; [{:type clojure.lang.ExceptionInfo
;; :message "Error on GET"
;; :data {:response #yada.response.Response{:representation {:media-type #yada.media-type[application/json;q=1.0], :charset #yada.charset.CharsetMap{:alias "UTF-8", :quality 1.0}}, :vary #{:media-type}}, :resource #function[backend.routes.examples.ts/fn--57734]}
;; :at [clojure.core$ex_info invoke "core.clj" 4593]}
;; {:type java.lang.IllegalArgumentException
;; :message "No implementation of method: :to-body of protocol: #'yada.body/MessageBody found for class: manifold.stream.async.CoreAsyncSource"
;; :at [clojure.core$_cache_protocol_fn invoke "core_deftype.clj" 554]}]
;; :trace
第三次尝试,使用core.async
通道(不同错误500):
(def get-stream
(yada (fn [ctx]
(-> (:response ctx)
(assoc :status 202)
(assoc :body (chan)))
{:representations [{:media-type "application/json"
:charset "UTF-8"}
{:media-type "application/edn"
:charset "UTF-8"}]}))
;; Error on the page :
;; 500: Unknown
;; Error on GET
;; #error {
;; :cause "No implementation of method: :to-body of protocol: #'yada.body/MessageBody found for class: clojure.core.async.impl.channels.ManyToManyChannel"
;; :via
;; [{:type clojure.lang.ExceptionInfo
;; :message "Error on GET"
;; :data {:response #yada.response.Response{:representation {:media-type #yada.media-type[application/json;q=1.0], :charset #yada.charset.CharsetMap{:alias "UTF-8", :quality 1.0}}, :vary #{:media-type}}, :resource #function[backend.routes.api.subscribe/subscribe$fn--64130]}
;; :at [clojure.core$ex_info invoke "core.clj" 4593]}
;; {:type java.lang.IllegalArgumentException
;; :message "No implementation of method: :to-body of protocol: #'yada.body/MessageBody found for class: clojure.core.async.impl.channels.ManyToManyChannel"
;; :at [clojure.core$_cache_protocol_fn invoke "core_deftype.clj" 554]}]
;; :trace
关键错误是:
"No implementation of method: :to-body of protocol:
#'yada.body/MessageBody
found for class: manifold.stream.async.CoreAsyncSource"
它揭示了你使用的yada版本试图胁迫一个它不理解的体型。yada的最新版本对可以发送到web服务器的内容更加宽容,并允许任何它不知道如何转换的内容。