sequential? is not really adding any value here - using a regex op will
*only* match something that's sequential.
The other thing to know here is that s/and creates a generator that
generates based on the first spec, then filters based on the subsequent
ones. So if you wanted to do sequences of an *even* number of numbers you
could do:
(s/exercise (s/and (s/* integer?) #(even? (count %))))
This will generate sequences of numbers and filter all that don't have an
even number of elements. If your generator is too broad or your filters
aren't selective enough, you may need to provide a custom generator:
;; generator creates any sequence of nums, but only want ones containing 42
(s/exercise (s/and (s/* integer?) #(some #{42} %)))
;; fails
;; add custom generator that generates random seq of nums, then injects 42
(s/def ::nums (s/* integer?))
(s/exercise (s/with-gen
(s/and ::nums #(some #{42} %))
(fn [] (gen/fmap #(conj % 42) (s/gen ::nums)))))
On Friday, June 10, 2016 at 10:01:48 AM UTC-5, Frank Versnel wrote:
>
> Hi,
>
> I'm currently playing around with clojure spec trying to write a spec for
> an old program I wrote and stumbled upon the following:
>
> Whenever I try to generate something that is both sequential and something
> else it doesn't really work most of the time.
> For example when I try to create a sequence of integers like this:
>
> (s/exercise (s/and sequential? (s/* integer?)))
>
> It will often fail to produce anything in the first 100 tries while:
>
> (s/exercise (s/and (s/* integer?)))
>
> works flawlessly every time. Maybe I'm doing something wrong or maybe I do
> need to
> write a custom generator for the sequential bit?
>
> Best regards,
>
> Frank
>
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