I would like to learn what is the idiomatic way to process every line of string with Babashka?

@yubrshen You can use *input* but this is honestly more for one-liners on the command line. For scripts you might want to use:

$ ls | bb -e "(first (line-seq (io/reader *in*)))"
"CHANGELOG.md"

io/reader is coming from

ok :)

Finally, this is what works for my need.

< samples.dat bb -i -o '(->> *input* (map (fn [line] (clojure.string/replace-first line #"Location=([^.,]+)[^,]+" #(str "Location=" (clojure.string/upper-case (last %1)))))))' I can use user/**input** inside of my script file to access the stdin as list of lines, but I have not figured out how to output lines to stdout inside my script. The above one-liner works, but it's getting hard to maintain. Is there such equivalent mechanism to let babashka to help to output lines to stdout from a script?

I can improve the readability but not keeping in the ecosystem of Clojure:

#!/usr/bin/env bash < $1 bb -i -o '(->> *input* (map (fn [line] (clojure.string/replace-first line #"Location=([^.,]+)[^,]+" #(str "Location=" (clojure.string/upper-case (last %1)))))))'

Is there any better approach, keeping my code mostly in Clojure development environment?

@yubrshen I'm not sure what you mean. You can put this code in a file and that should work? https://clojurians.slack.com/archives/CLX41ASCS/p1603213831030700?thread_ts=1603176112.006000&cid=CLX41ASCS

Without babashka in/output flags:

(ns my-script
  (:require [ :as io]
            [clojure.string :as str]))

(defn lines []
  (line-seq (io/reader *in*)))

(->> (lines)
     (map
      (fn [line]
        (str/replace-first line #"Location=([^.,]+)[^,]+"
                           #(str "Location=" (str/upper-case (last %1))))))
     (run! println))

This also works with Clojure on the JVM

Yes, exactly, this is what I'm looking for to learn to have the script to run both with Clojure and Babashka. Thanks a million!

:thumbsup:

I don’t use metadata that much so I’m not sure how to read it 😬

The metadata preceding the ($ ...) form are the options for that form

So in this case the metadata is attached to the return value of ($ ls -la Dockerfile) and used by ($ cat) ?

no, the metadata is only attached to ($ cat), this is how metadata works.

it is the same as writing (process '[cat] {:out sw})

I’m not sure if my clojure knowledge is helping me here or actually making it more complex. macroexpand-1 is not helping here (:exit (check ($ ($ ls -la Dockerfile) cat)))

ah so the metadata is attached to the form and this is something https://github.com/babashka/process/commit/182d08bcdc6f75f5cb6e59fb2808a125f263dac3#diff-b5668fe5b029db7465ab915136e20ef98b6ddf9585094c7ebbf325cbf9d0fa04R167 😅

yes :)

ok so I think there are two people who will have no issue using this. beginners and more advanced clojure users

But maybe it just a valueable lesson about clojure 🙂 Thank you

I have updated my mental model

Love the $ macro, and I like metadata use, just took me a little bit of time to figure out how to adopt it for my use. I've ran into some other weird issue that when I use (check) it gets stuff if there is no error, but goes through if there is error. I will try to reproduce with smaller use case and report later.

hmm ok, thanks!

https://github.com/borkdude/babashka/issues/575#issuecomment-713105955 this is pretty cool

Yeah! Please let me know about the bug. There's still time to fix before it goes into 0.2.3

Sorry, very busy this week, I will try to isolate it at some point. Just need to try it with something simpler then aws command line. If I uncomment check above it get stuck on the success, but not on error.

what does stuck mean?

no output, like it is waiting for something

and I have ^C it

ah, this explains it. yes, check will wait for the process to exit, else it can't inspect the exit code.

so the process is maybe waiting for something?

check = deref + throw on non-zero

hmm, strange it definitely exist w/o check

is there a way to dump stack, like SIGQUIT or something?

I've tried some https://www.graalvm.org/reference-manual/native-image/NativeImageHeapdump/ but no luck

How big is the JSON it's trying to write to stdout?

@U01BDT7622X Can you try with e.g.:

{:out (io/file "out.json")}

when i added it to $ it writes out 148k file and exits

if i put #_ in front of it, it gets stuck again

some kind of buffering thing, try maybe with big .json file?

ah so that may be it

yeah, so:

(-> (process ["cat"] {:out (io/file "/tmp/foo.csv") :in (io/file "/Users/borkdude/Downloads/1mb-test_csv.csv")}) check)

@U01BDT7622X A solution:

user=> (def csv (with-out-str (-> (process ["cat"] {:out *out* :in (io/file "/Users/borkdude/Downloads/1mb-test_csv.csv")}) check)))
#'user/csv
user=> (count csv)
1000448

whereas

(def csv (with-out-str (-> (process ["cat" "foo"] {:out *out*}) check)))

I'll write a note about this in the docs

This is probably also a good option:

(def sw (java.io.StringWriter.))
(-> (process ["cat"] {:in (slurp "") :out sw}) check)
(count (str sw)) ;; 1043005

as long as it has a way to write the stream somewhere

maybe it would be convenient to have an :out :string for this use case

yep, that is the case, so it works w/ w-o-s

yes, :string is good idea, since it is a common case to check and :out slurp

@U01BDT7622X Are you testing with bb or directly on the JVM?

bb from builds

that is why i could not dump stack to see where it is stuck

This should now work in the JVM lib:

(testing "output to string"
    (is (string? (-> (process ["ls"] {:out :string})
                     check
                     :out))))

c00l, i will test it on my use case once it is build

ok, just pushed it. should be a few minutes

Should be there now. With this enhancement the following now also works:

user=> (count (-> (process ["cat"] {:in (slurp "") :out (io/file "/tmp/download.csv")}) check :out slurp))
1043005

i.e. :out contains the same value as was put in

it works! thank you for all the hard work!