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Michiel Borkent 2019-08-18 00:31:39 +02:00
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README.md
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@ -19,21 +19,36 @@ $ bb '(vec (dedupe *in*))' <<< '[1 1 1 1 2]'
If you're a bash expert, you probably don't need this. But for those of us who
can use a bit of Clojure in their shell scripts, it may be useful.
Babashka runs as a binary and uses [sci](https://github.com/borkdude/sci) for
interpreting Clojure, which results in faster startup times:
Babashka runs as a binary which results in faster startup times:
``` shellsession
$ time clojure -e "(require '[clojure.java.shell :as shell])" ./download_html.clj
2.15s user 0.17s system 242% cpu 0.959 total
$ time clojure -e "(+ 1 2 3)"
6
clojure -e "(+ 1 2 3)" 3.29s user 0.32s system 99% cpu 3.638 total
$ time bb -f ./download_html.clj
0.00s user 0.00s system 69% cpu 0.010 total
$ time plk -e '(+ 1 2 3)'
6
plk -e '(+ 1 2 3)' 1.34s user 0.16s system 127% cpu 1.172 total
$ time bb '(+ 1 2 3)'
6
bb '(+ 1 2 3)' 0.01s user 0.01s system 37% cpu 0.046 total
```
A trade-off is that [sci](https://github.com/borkdude/sci) implements only a
subset of Clojure. If you need more, feel free to post an issue or check out
other Clojure scripting
[projects](https://github.com/borkdude/babashka#related-projects).
It uses [sci](https://github.com/borkdude/sci) for interpreting Clojure. A
trade-off is that [sci](https://github.com/borkdude/sci) implements only a
subset of Clojure. Also, execution time may be slower than Clojure on the JVM or
(self-hosted) ClojureScript for more CPU-intensive calculations like:
``` shellsession
(last (take 1000000 (repeatedly #(+ 1 2 3))))
```
This would take 5 seconds using babashka, around half a second using self-hosted
ClojureScript and around 200ms in Clojure on the JVM.
So the sweet spot for babashka is executing tasks from the command line where
fast startup time is preferred, in the same space where you would use bash.
## Status
@ -80,13 +95,6 @@ bb [ --help ] | [ --version ] | ( [ -i ] [ -o ] | [ -io ] ) [ --stream ] ( expre
Type `bb --help` to see a full explanation of the options.
The input is read as EDN by default. If the `-i` flag is provided, then the
input is read as a string which is then split on newlines. The output is printed
as EDN by default, unless the `-o` flag is provided, then the output is turned
into shell-scripting friendly output. To combine `-i` and `-o` you can use
`-io`. When using the `--stream` option the expression is executed for every
line or EDN value from stdin.
The `clojure.core` functions are accessible without a namespace alias.
The following Clojure namespaces are required by default and only available