I am trying to use Clojure Spec to define a data structure containing a java.time.LocalDate element:
(s/def :ex/first-name string?)
(s/def :ex/last-name string?)
(s/def :ex/birth-date (s/valid? inst? (java.time.LocalDate/now)))
(s/def :ex/person
(s/keys :req [:ex/first-name
:ex/last-name
:ex/birth-date]))
(def p1 #:ex{:first-name "Jenny"
:last-name "Barnes"
:birth-date (java.time.LocalDate/parse "1910-03-15")})
(println p1)
produces the following output
#:ex{:first-name Jenny, :last-name Barnes, :birth-date #object[java.time.LocalDate 0x4ed4f9db 1910-03-15]}
However, when I test to see if p1 conforms to the :ex/person spec, it fails:
(s/valid? :ex/person p1)
ClassCastException java.lang.Boolean cannot be cast to clojure.lang.IFn clojure.spec.alpha/spec-impl/reify--1987 (alpha.clj:875)
Looking closer at the Clojure examples for inst?, I see:
(inst? (java.time.Instant/now))
;;=> true
(inst? (java.time.LocalDateTime/now))
;;=> false
However, I don't see an obvious reason as to why that returns false. This seems to be the root of my issue, but I have not found a solution and would like some help.
You're probably looking for
instance?
- and your example fails, because in:this part
(s/valid? inst? (java.time.LocalDate/now))
should be a function (predicate), not boolean. The full code:inst?
won't work here, becauseInst
is a protocol, used to extendjava.util.Date
andjava.time.Instant
:And you can use
satisfies?
to check whether some object satisfies given protocol: