On Feb 16, 12:26 pm, alux <alu...@googlemail.com> wrote:
> Hello,
>
> the current state of Conway's Prime Machine is athttp://paste.lisp.org/+21BR
Instead of using a quoted list, a vector is more idiomatic in Clojure.
>
> I'l go on learning. The next state should be seperation of print and
> produce. Currently (conway-pm) doesnt return stuff. I dont know if
> Clojure can produce infinite lists, like Haskell, and print the items
> as they come.
It can. They're just called infinite sequences. For example, (iterate
inc 0) produces an infinite sequence of integers from 0 onwards. You
can also construct your own infinite sequences using the lazy-seq
macro in a pattern like the following:
(defn count-down [x]
(lazy-seq (cons x (count-down (dec x))))) ; lazy-seq doesn't
actually evaluate the cons until it's requested
However, often you should start by looking at the core library and see
if there already exists a function to produce a list that you need,
and only afterwards construct things from scratch. For example,
"repeatedly" and "iterate" are common seq-producers, and "map" and
"filter" are used to transform them. They're all lazy, so infinite
seqs are not problematic.
There is one thing you need to look out for though: Never define a
global reference to an infinite seq. The items in a sequence are
cached, so if you define a global reference to the head, no part of
the seq will ever be garbage collected and its memory usage will be
unbounded.
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