Comments on: Some notes about Clojure

By: Tuple parameter unpacking in 3.x - Page 2 | keyongtech

Tuple parameter unpacking in 3.x - Page 2 | keyongtech — Sun, 18 Jan 2009 16:49:18 +0000

[...] from scratch similar native pattern- matching features in CPython, like ones of Closure: http://items.sjbach.com/16/some-notes-about-clojure Or better ones of Scala, (or even OcaML, but those are static), etc, that avoid that pain and [...]

By: Suzy

Suzy — Mon, 24 Nov 2008 13:14:15 +0000

Way, Way, over my head but I think it looks great! Well done, Stevo.

By: Robert Virding

Robert Virding — Wed, 08 Oct 2008 07:09:16 +0000

Coming from a pattern matching world the destructuring seems pretty simple, at least to what I am used to. Check out Lisp Flavoured Erlang (LFE) for a lisp example of more destructuring.

By: Stephen Bach

Stephen Bach — Tue, 07 Oct 2008 17:54:10 +0000

Thanks mb. Looks like for is perhaps more a device for list comprehensions than iteration.

By: mb

mb — Tue, 07 Oct 2008 17:39:37 +0000

Some notes: - anonymous fns support also variadic arguments: #(apply str %&) - for can do far more than just iterating:

    (for [x [1 2 3 4 5 6] :while (< x 3)
          y [1 2 3 4 5 6] :when (even? y)]
      [x y])

gives a (lazy) ([1 2] [1 4] [1 6] [2 2] [2 4] [2 6]). It has nothing to do with for loops in other languages. In particular it is not a way of doing things for side effects. That is what doseq is supposed to do.

By: Stephen Bach

Stephen Bach — Tue, 07 Oct 2008 17:20:47 +0000

Nice, I didn’t know that functions were implicit recur targets. That’s really smart.

By: fogus

fogus — Tue, 07 Oct 2008 16:25:44 +0000

RE: `(recur)`

You make it look ‘more’ like recursion by making the recur target the enclosing `defn` instead. That is:

(defn member [x sq]
  (if (seq? sq)
    (if (= x (first sq))
      sq
      (recur x (rest sq)))))

(member 'a '(1 2 3 a b c))

The power of `recur` comes from the fact that it will work on lambdas as well… but it would be nice for the JVM to provide TCO. The combination of TCO and recur would be sweet.
-m