I'm still learning clojure and wrote this decidedly unfunctional bit of
code as part of a common lisp style DESCRIBE function.
I was wondering what experienced clojure-ers (what's the proper
reference?) might suggest to make this function less ugly.
I realize making a purely functional version of this is probably the
clojure thing to do, but it wasn't worth my time,
nor did I think it would make the code shorter (correct me if I'm wrong).
Anyway, with regard to mutable state is there a more concise and/or
preferred way to do this?
The function in question is just querying the many maps of a namespace to
yield another map with some interpretations of the namespace with respect
to a given symbol. I am struggling with some of the capabilities of
namespaces and so this was just a bit of learning code for me, though I
have to say my resulting DESCRIBE function has been really useful to me.
At some point when it's not a total embarrassment perhaps I'll post it.
Thanks for your suggestions:
(defn ns-symbol-relationship
"Return a map of entries that describe the relationship of a symbol to a
given namespace."
[ns symbol]
(if (not (symbol? symbol))
(throw (Exception. (str "ns-symbol-relationship expected symbol, got "
symbol))))
;; ns-name ns-aliases ns-imports ns-interns ns-map ns-publics ns-refers
(with-local-vars [result (transient {})]
(when (= (ns-name ns) symbol) ;ns-name gives a symbol
(var-set result (assoc! (var-get result) :names-ns ns))) ;symbol
names namespace
; ns-aliases gives a map, but the k/v types/semantics are presently
unknown
(doseq [[k v] (seq (ns-aliases ns))]
(when (= k symbol)
(var-set result (assoc! (var-get result) :alias-for v)))
(when (= v symbol)
(var-set result (assoc! (var-get result) :aliased-by k))))
;; ns-imports keyed by symbol, valued by class
(if-let [v (get (ns-imports ns) symbol)]
(var-set result (assoc! (var-get result) :imports v))) ;symbol
names imported class
;; ns-interns gives a map, keys are symbols in the namespace, values
are vars( and special forms?)
;; that they map to.
(if-let [v (get (ns-interns ns) symbol)]
(var-set result (assoc! (var-get result) :interns v)))
;; ns-maps gives a map, value types/semantics are unknown
(if-let [v (get (ns-map ns) symbol)]
(var-set result (assoc! (var-get result) :maps-to v)))
;; ns-publics gives a map of public intern mappings, presumably a
subset of ns-interns
(if-let [v (get (ns-publics ns) symbol)]
(var-set result (assoc! (var-get result) :interns-publicly v)))
;; ns-refers gives a map of refer-mappings, value semantics unknown
(if-let [v (get (ns-refers ns) symbol)]
(var-set result (assoc! (var-get result) :refers-to v)))
(persistent! (var-get result))))
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