I forgot to mention that if you run this with alpha2, this example won't
work due to a bug, but that is fixed in master for alpha3.
On Wednesday, May 25, 2016 at 2:38:07 PM UTC-5, Alex Miller wrote:
>
> s/or creates a spec and s/alt creates a regex op. Regex ops can be
> combined to describe a single sequence. Use s/alt if you are matching
> alternative regex expressions in a sequential context - in particular where
> the branches of the alt are themselves regex ops. Use s/or when matching a
> single item. There are indeed cases where you could use one or the other
> and even yield the same result, but they have different affordances and
> intent when used in combination with other things.
>
> This is an example where s/alt decides between nested regex ops (and s/or
> won't work here):
>
> user=> (s/def ::s (s/* (s/alt :key-pair (s/cat :a keyword? :b keyword?)
> :nums (s/+ number?))))
> :user/s
> user=> (s/conform ::s [:a :b 1 2 3 :c :d :e :f 4 5])
> [[:key-pair {:a :a, :b :b}] [:nums [1 2 3]] [:key-pair {:a :c, :b :d}]
> [:key-pair {:a :e, :b :f}] [:nums [4 5]]]
>
> If we tried this with an s/or, it would try to match a new regular
> expression under the or and fail:
>
> user=> (s/def ::s' (s/* (s/or :key-pair (s/cat :a keyword? :b keyword?)
> :nums (s/+ number?))))
> :user/s'
> user=> (s/conform ::s' [:a :b 1 2 3 :c :d :e :f 4 5])
> :clojure.spec/invalid
>
> And you would instead match something like this:
>
> user=> (s/conform ::s' [[:a :b] [1 2 3] [:c :d] [:e :f] [4 5]])
> [[:key-pair {:a :a, :b :b}] [:nums [1 2 3]] [:key-pair {:a :c, :b :d}]
> [:key-pair {:a :e, :b :f}] [:nums [4 5]]]
>
>
> On Wednesday, May 25, 2016 at 12:48:05 PM UTC-5, Brent Millare wrote:
>>
>> What's the difference between clojure.spec/or and clojure.spec/alt? They
>> seem to accept the same inputs, multiple keyword-predicate pairs, and
>> output tagged values when used with clojure.spec/conform. Is
>> clojure.spec/or usable within a regular expression?
>>
>
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