Question

Here “graph” is higher-order function that returns a function with config set in its scope:

(ns bulbs.neo4jserver.graph)

(defn out1
  "Test func that simply returns out1."
  [config]
  "out1")

(defn graph
  [config]
  (fn [func & args]
    (apply func config args)))

You create an instance of graph, which can then be used to call other functions and automatically pass in the config arg:

(def g (graph {:root-uri "http://localhost"}))

(g out1)
;; => "out1"

This works; however, if you require/import graph into another namespace, then you have to prefix each function call with the graph namespace:

(ns bulbs.neo4jserver.junk
  (:require [bulbs.neo4jserver.graph :as graph]))

(def g (graph/graph {:root-uri "http://localhost"}))

;; would rather do (g out1)
(g graph/out1)

Instead, I want to explicitly specify the namespace in the apply function so that users don’t have to:

(defn graph
  [config]
  (fn [func & args]
    ;; somehow specify the graph namespace here
    (apply func config args)))

What’s the best way to do this?

Answer 1

You can pass symbol instead of function and resolve it in graph function:

(defn graph
  [config]
  (fn [func & args]
    (apply (ns-resolve 'bulbs.neo4jserver.graph func) config args)))

And call it:

(ns bulbs.neo4jserver.junk
  (:require [bulbs.neo4jserver.graph :as graph]))

(def g (graph/graph {:root-uri "http://localhost"}))

(g 'out1)

But g is not an high-order function any more. It takes symbol, not function. Personally I don’t like this approach. Why don’t you like specifying namespace? May be you can do what you need with macro too, but I don’t know macros well.

EDIT

Don’t do it. Use regular functions as explained by @Ankur and @Gert in comments.