I would back way up to the beginning and reconsider your ::board spec.
Generally for any data where the structures are homogenous, you're probably
better off using one of the collection specs like coll-of (or map-of,
every, every-kv) rather than a regex, which should primarily be used when
you have a sequential structure with syntactic "parts" to it (such as an
arg string or other "dsl" type use case).
Because s/and flows conformed values you can get the same effect as you did
with &:
(s/def ::board (s/and (s/coll-of ::row :min-count 1) #(apply = (map count
%))))
Your generator seems like it should work. You might also want to constrain
more tightly than pos-int? to keep it from getting out of hand. You could
use something like (s/gen (s/int-in 1 10)) for example.
On Monday, October 17, 2016 at 2:32:20 PM UTC-5, Jason Courcoux wrote:
>
> Hi.
>
> I've been experimenting with clojure spec and a game of life problem, and
> have been trying to spec a rectangular board of unknown size made up of a
> collection of rows, each of which contain an equal number of cells. My
> initial attempt was:-
>
> (def cell? #{0 1})
>
> (s/def ::row (s/coll-of cell? :min-count 1))
>
> (s/def ::board (s/& (s/+ ::row)
> #(apply = (map count %))))
>
>
> This appears to work, but I'm wondering if there is a better way to
> specify the constraint that every row should be the same length? What would
> be the recommended way to achieve this?
>
> Following on from this, I then wanted to generate input boards and
> exercise a function so I tried the following which give me an
> ArityException:-
>
> (s/def ::board (s/with-gen
> (s/& (s/+ ::row)
> #(apply = (map count %)))
> #(gen/bind (s/gen pos-int?)
> (fn [n]
> (s/gen (s/coll-of (s/coll-of cell? :count
> n)))))))
>
> (s/fdef my-function :args (s/cat :board ::board))
>
> (defn my-function [board])
>
> (s/exercise (:args (s/get-spec `my-function)) 1)
>
> => ([([1] [0] [0] [1] [0]) {:board [[1] [0] [0] [1] [0]]}])
>
> (s/exercise-fn `my-function)
>
> => ArityException Wrong number of args (20) passed to: user/my-function
>
>
This is pretty interesting and the number 20 is pretty suspicious as that's
the max number of args per function - I'm guessing pos-int? is causing
problems there.
>
>
> If I try and do something similar without the custom generator such as:
>
> (s/def ::coll (s/coll-of (s/coll-of int? :count 2)))
>
> (s/fdef my-function2 :args (s/cat :board ::coll))
>
> (defn my-function2 [board])
>
> (s/exercise (:args (s/get-spec `my-function2)) 1)
>
> => ([(*[*[0 -1] [0 -1] [0 -1]*]*) {:board [[0 -1] [0 -1] [0 -1]]}])
>
> (s/exercise-fn `my-function2)
>
> This all works as expected. I can see that there is an extra level of
> nesting here though and this must be where the error is coming from, as
> it's applying my-function to the collection rather than using it as a
> single argument - but I'm not sure what is causing this difference.
>
> These look the same in terms of structure:
>
> (gen/sample (s/gen ::coll) 1)
> => ([[-1 -1] [-1 0] [0 -1] [-1 -1] [-1 0] [-1 0]])
>
> (gen/sample (s/gen ::board) 1)
> => ([[0 1] [1 1] [1 1] [1 1] [1 1] [0 0] [0 1]])
>
> (s/fdef my-function :args (s/cat :board ::board))
>
> (s/fdef my-function2 :args (s/cat :board ::coll))
>
>
> But these don't:
>
> (gen/sample (s/gen (:args (s/get-spec `my-function))) 1)
> => (([1 0] [0 0] [0 1] [0 1] [1 1]))
> (gen/sample (s/gen (:args (s/get-spec `my-function2))) 1)
> => (([[-1 -1] [-1 -1] [0 0] [0 0] [-1 0] [-1 -1] [0 0]]))
>
>
> I'm sure it's something obvious, but I been looking for a couple of hours
> and can't seem to see it - could someone please help point me in the right
> direction.
>
> Thanks in advance.
>
> Jason
>
>
> --
> Jason Courcoux
>
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