Clojurians Log v2
beginners
Hi I’m working with monger the mongoDB Clojure wrapper, I’m trying to create a user on the database, the function seems simple enough
add-user
(add-user db username password)
Adds a new user for this db(db/add-user db "test" "12345")java.lang.String cannot be cast to [C(defn add-user
"Adds a new user for this db"
[^DB db ^String username ^chars password]
(.addUser db username password))
Both [C and ^chars are used for arrays of characters (which is different from String).
Does (db/add-user db "test" (.toCharArray "12345")) work?
Oh that works! If you don’t mind me asking, whats the difference between (char "12345") and (.toCharArray "12345")
char will try to cast its argument to a single character (type is char) and (.toCharArray "asf") will return an array of chars (type is similar to char[]) for a given string
That makes sense, thanks!!!
Living Clojure is a great book -- your local library might have some clojure books or you could request your local library to get some ^.^
why (- 5 -10) gives 15 ?
this is called prefix notation.
(- 5 -10) in clojure is equivalent to (5 - (-10)) in regular math
can i define clojure.test tests in a loop?
(defn generate-tests
[]
(deftest "major test"
(for [case [1 2 3]]
(testing (str "is " case " = 1")
(is (= 1 case))))))
I do it like this:
(defn exercise-case
[x]
(is (= 1 x)
(str "is" x "= 1")))
(deftest exercise-1
(exercise-case 1))
(deftest exercise-2
(exercise-case 2))
(deftest exercise-3
(exercise-case 3))is is printed on test failure, just like testing but it can be calculated on demand in its scope
use doseq
for is not a loop
putting defs inside other forms is pretty much never good
heh, yeah i knew the for wouldn't work there
why didn't i think of doseq.. thanks @dpsutton
yup, i get triggered every time i read through https://github.com/ptaoussanis/sente
https://clojure.github.io/clojure/clojure.test-api.html#clojure.test/are
is there a function to check if a given symbol is a multimethod?
(instance? clojure.lang.MultiFn x)
ty ty
a given object
Is it best practice under Linux to install leiningen from the distro's package manager, or should I install something under my user?
The package manage will be slightly simpler and familiar process and should ensure the binaries do not conflict with anything else on the execution path.
If you wish to have a specific version, then install in _/.local/bin which is on most exec paths by default if that directory exists.
If configuring a multi-user system and then install in /user/local/bin using sudo instead.
i'd recommend not using the distro's version. Those come with upgrades prevented. If you install it yourself you can easily run lein upgrade <version> and easily change the version if there are bugs, incompatibilities, etc
<https://github.com/technomancy/leiningen/blob/master/bin/lein-pkg#L107>