You are correct. The struct is a single message. The messages object holds a
ref to N of them (initially an empty vector).
Individual messages are added by alter ... conj in add-message.
Stu
>
> Ok, then I understand why it didn't work, but that means that the
> struct (that is sent by the add-message function) is put in a sequence
> somewhere on the way to being validated. Is this right, and where does
> this happen?
>
>
> ;All the relevant code
>
> (defstruct message :sender :text)
>
> (def validate-message-list
> (partial every? #(and (:sender %) (:text %))))
>
> (def messages (ref [] :validator validate-message-list))
>
> (defn add-message [msg]
> (dosync (alter messages conj msg)))
>
> (add-message (struct message "mm" "first message"))
>
>
>
>
>
> On Jun 23, 12:58 pm, Stuart Halloway <stuart.hallo...@gmail.com>
> wrote:
>> Hi Michele,
>>
>> Pass a sequence of maps, not just a map:
>>
>> (every? #(:x %) [{:x "s"}])
>> -> true
>>
>> Cheers,
>> Stu
>>
>>
>>
>>> In the book "Programming Clojure" (p2_0, pdf, page 185) "Adding
>>> Validation to Refs" there is this code:
>>
>>> (def validate-message-list (partial every? #(and (:sender %) (:text
>>> %))))
>>
>>> This works fine as a validator, but when I try the code directly - not
>>> as a validator - it returns false. I also tested with a simple "if" to
>>> see the difference.
>>
>>> (every? #(:x %) {:x "s"})
>>> -> false
>>
>>> (if (#(:x %) {:x "s"}) "TRUE" "FALSE")
>>> -> "TRUE"
>>
>>> What do I not understand?
>>
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