Clojurians Log v2

Hi.

Can planck handle stdin when run as a (Unix) shell script?

Would like to create a clojure equivalent to, say, “wc -l” (count lines in stream) Unix command. Tried this:

which fails.

@gamecubate You need a closing brace and closing paren:

#!/usr/bin/env planck
(require '[planck.core :as core])
(println (count (core/line-seq core/*in*)))

Sorry, was writing from scratch; silly mistake but script still fails.

Am doing more tests

Now this one works:

I think that could be it.

$ cat /etc/services | wcl

So, all good.

Right. Planck 1.17 is based on ClojureScript 1.9.229, and in that version of ClojureScript, require doesn’t exist (it is a REPL special). So, your solution works with Planck 1.17. On the other hand, the Planck 2.0.0 release candidate is based on a newer ClojureScript, where require is a macro, and can be used as in your first example.

I had opened a git issue requesting some documentation on just that. Will edit it to include this code if you think it’s correct.

Great.

Yeah, to address your ticket, perhaps we can add some more to the http://planck-repl.org site content

In the updated site document for 2.0.0, require has already been removed from the docs for Planck’s REPL specials (https://github.com/mfikes/planck/blob/master/site/src/repl.md#repl-specials), but perhaps an example showing your use of *in* is still a good addition.

Would be really helpful to help Unix scripters like I.

Took a while (30 mins or so) to get it right.

Doc would have shaved that to 1. 🙂

Yeah, perhaps a section on stdin in here https://github.com/mfikes/planck/blob/master/site/src/scripts.md

Yes, exactly.

Thanks for a great tool BTW

Now trying something more demanding: a “sum stdin numbers” script. Something invoked like

echo 1 2 3 | tally

You might want to use the reader to parse the integers

Yes.

(require '[cljs.tools.reader :as r])
(r/read-string “1”)

What if string = “1 2 3”. Assuming I will have to split it then map r/read-string over each element.

(clojure.string/split "1 2 3" #" “)

Exactly 🙂

(reduce + (map r/read-string (clojure.string/split “1 2 3”)))

Ah yes. Thanks a bunch.

👍 @niamu

Better.

cat nums.txt | tally

6
15
24

where tally = script above.