On Thursday, October 5, 2017 at 1:52:47 PM UTC-5, Alex Bezhan wrote:
>
>
>
> down votefavorite
> <https://stackoverflow.com/questions/46592767/how-do-i-make-custom-clojure-spec-generator#>
>
> I'm trying to spec the following data structure called Connection:
>
> {:id "some string" :channel "instance of org.httpkit.server.AsyncChannel" }
>
> Here is my spec:
>
>
> (defn make-channel []
> (proxy [AsyncChannel] [nil nil]
> (toString [] "mock AsyncChannel")))
> (defn channel-gen
> []
> (->> (s/gen (s/int-in 0 1))
>
>
^^ s/int-in is exclusive on the end of the range, so this will only return
0.
>
> (gen/fmap (fn [_] (make-channel)))))
>
>
I don't understand why this is using fmap / gen at all here unless you've
cut this down.
>
> (s/def ::channel (s/spec (::channel-type)
>
>
^^ just ::channel-type, not (::channel-type) here
>
> :gen channel-gen))
>
>
In general, making a generator that re-invokes a function every time is
somewhat at odds with how generators work.
>
> (s/def ::id string?)
> (s/def ::connection (s/keys :req-un [::channel ::id]))
> (s/fdef make-connection
> :args ::channel
> :ret ::connection)
>
>
>
I think here you probably want to wrap a regex spec around the channel spec
(you're specing the args as if you invoked them using apply):
(s/fdef make-connection
:args (s/cat :ch ::channel)
:ret ::connection)
> I'm getting the following error and I have no clue what is wrong here:
>
> clojure.lang.ExceptionInfo: Unable to construct gen at: [] for:
> gameserve.ws$make_connection@788ffa19
> clojure.lang.Compiler$CompilerException: clojure.lang.ExceptionInfo: Unable
> to construct gen at: [] for: gameserve.ws$make_connection@788ffa19
> #:clojure.spec.alpha{:path [], :form #object[gameserve.ws$make_connection
> 0x788ffa19 "gameserve.ws$make_connection@788ffa19"], :failure :no-gen}
>
>
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