Replying to your numbered points, it is idiomatic in Clojure to interoperate directly with Java libraries, so getting the full Java stacktrace can be helpful if you are calling into Java objects in some unexpected or unsupported way. Sounds like a good idea; I’ve often at least wished for a settable option which would allow … Read more
No, it’s intentionally not possible. There was a conversation on the ClojureScript mailing list recently related to :refer :all and it looks like it will never be supported. To quote David Nolen from that thread: It’s just bad style and as far I know the only reason it hasn’t changed in Clojure is because the … Read more
REPL = read eval print loop. Step through the read-eval process. READ: Clojure sees the string “(`a)”, parses it and ends up with a data structure. At read time, reader macros are expanded and not much else happens. In this case, the reader expands the backquote and ends up with this: user> (read-string “(`a)”) ((quote … Read more
There are a few fundamental difference between them: Data Model Both Neo4j and Datomic can model arbitrary relationships. They both use, effectively, an EAV (entity-attribute-value) schema so they both can model many of the same problem domains except Datomic’s EAV schema also embeds a time dimension (i.e. EAVT) which makes it very powerful if you … Read more
There is ongoing work towards doing this with unification in the core.match ( https://github.com/clojure/core.match ) library. Depending on exactly what you want to do, another common way is to use defmulti/defmethod to dispatch on arbitrary functions. See http://clojuredocs.org/clojure_core/clojure.core/defmulti (at the bottom of that page is the factorial example)
In Prolog’s terms, condA is “soft cut” a.k.a. *->, where A *-> B ; C is like (A, B ; not(A), C), only better ; whereas condU is “committed choice”, a combination of once and a soft cut so that (once(A) *-> B ; false) expresses (A, !, B) (with the cut inside): condA: A *-> … Read more
Try using count: (count ‘(1 2 3)) => 3 (count [1 2 3]) => 3
The usual solution is (defn transpose [m] (apply mapv vector m))
It is Leiningen configuration. Have a look at : Sample project.clj. If you are creating a Pedestal application, then that is why they want to skip AOT: Why does pedestal skip AOT? and in Heroku context: Reason for skipping AOT?
You could wrap your predicate with the is macro from clojure.test (defn string-to-string [s1] {:pre [(is (string? s1))] :post [(is (string? %))]} s1) Then you get: (string-to-string 10) ;FAIL in clojure.lang.PersistentList$EmptyList@1 (scratch.clj:5) ;expected: (string? s1) ;actual: (not (string? 10))