Suppose you have the following xml to parse in your file: <high-node> <low-node>my text</low-node> </high-node> you load clojure.xml: user=> (use ‘clojure.xml) when parsed, the xml will have the following structure: {:tag :high-node, :attrs nil, :content [{:tag :low-node, :attrs nil, :content [“my text”]}]} and then you can seq over the content of the file to get … Read more
Even shorter : user> (clojure-version) “1.2.0-beta1” user> Oops, I have to upgrade…
user=> (defn find-first [f coll] (first (filter f coll))) #’user/find-first user=> (find-first #(= % 1) [3 4 1]) 1 Edit: A concurrency. 🙂 No. It does not apply f to the whole list. Only to the elements up to the first matching one due to laziness of filter.
[EDIT 2] Per M Smith’s comment below, this accomplishes the same but provides sorting by method name and only returns methods: (print-table (sort-by :name (filter :exception-types (:members (r/reflect “foo”))))) [/EDIT 2] [EDIT] My original answer refers to Clojure 1.2, but things have changed with Clojure 1.3. This works without any reliance on Clojure’s contrib libraries … Read more
Kawa, ABCL, and SISC are reimplementations of existing languages that are quite long in the tooth. They are excellent if for some reason you want to use standard Scheme or standard Common Lisp on the JVM. Clojure is a new language. It doesn’t fill a gap. It adds entirely new possibilities. It favors a purely … Read more
There are some extremely cool use cases. One example is in GUI programming – I saw this while developing a GUI app in real time as it was running beside my Emacs: I added code for a new button and hit “C-c C-c” to compile that single function, and the button just appeared in the … Read more
let creates a lexically scoped immutable alias for some value. binding creates a dynamically scoped binding for some Var. Dynamic binding means that the code inside your binding form and any code which that code calls (even if not in the local lexical scope) will see the new binding. Given: user> (def ^:dynamic x 0) … Read more
Main idea of adding :refer to :require is to get rid completely of :use, leaving only one operator to load other packages. You can emulate existing :use with (:require [my.lib :refer :all])…
As the page you linked described, next is stricter than (the new behaviour of) rest because it needs to evaluate the structure of the lazy cons to know whether to return nil or a seq. rest on the other hand always returns a seq, so nothing needs to be evaluated until you actually use the … Read more
You have to add the :private true metadata key value pair. (def ^{:private true} some-var :value) ;; or (def ^:private some-var :value) The second form is just a short-hand for the first one.