8 ms·

A Tour of Hell – Shell scripting Haskell dialect

139 points by kreyenborgi 2y ago

pvsnp 2y ago
I've wanted many things from shell but never to write Haskell in Shell. This turned something relatively naturally expressible into something so complex that requires type theory
- sinkasapa 2y ago
  There is no reason why one has to enjoy a haskell-like syntax over Bourne shell syntax but I think you're wrong about the tool. The author states that "It should have no abstraction capabilities (classes, data types, polymorphic functions, etc.)." Granted, there may be types but without those abstractions, I don't think you need to know much of anything about type theory.
- eru 2y ago
  You could use the Scheme Shell instead, if you don't like static typing. https://en.wikipedia.org/wiki/Scsh https://en.wikipedia.org/wiki/Scsh And specifically https://en.wikipedia.org/wiki/Scsh#%22Acknowledgments%22 https://en.wikipedia.org/wiki/Scsh#%22Acknowledgments%22
jonotime 2y ago
How was this page generated? I have a marp presentation (https://github.com/jonocodes/awesome-keyboards https://github.com/jonocodes/awesome-keyboards) that I would like to have shown on a single page like this with the notes expanded.
- cryptonector 2y ago
  I really like this page, with slides on the left and blog on the right.
chongli 2y ago
Interesting but not a great piece for anyone not into functional language design. A pretty deep dive into the "how" while completely ignoring the "why."
- rwmj 2y ago
  Or indeed the "what". Did he ever show an example of what the shell scripts look like? I couldn't see it.
  - simonmic 2y ago
    The first link takes you to the home page, which links to examples; probably a better starting point. https://chrisdone.github.io/hell https://chrisdone.github.io/hell
    - rwmj 2y ago
      If you're giving a presentation, you should start by telling the audience what it is you're talking about. Someone in the audience won't have a clue, and usually most of the audience have no clue.
- tmoertel 2y ago
  Chris discusses the rationale in his blog post at https://chrisdone.com/posts/hell/ https://chrisdone.com/posts/hell/
  - chongli 2y ago
    Thanks for this! I read that but I'm still not convinced. Quote: They lean far too heavily on sub processes to do basic things. I thought this was the whole point of a unix scripting language! Most of the scripts I'm writing are not interactive REPLs or string-parsers, they're glue code for batch-invoking commands on files. Stuff like converting a bunch of FLAC files into MP3 with lame or avi video files into mkv with ffmpeg. What bash offers me is very terse command invocation and powerful filename globbing, including regexp substitution. Scripts like this are generally not intended to be used more than once or twice, and so a type system like Haskell provides is irrelevant here. If you're writing something that's going to be iterated on and maintained for years then you're writing an application, not a script.
simonmic 2y ago
As a haskeller, and shell scripter, I find this a refreshing and exciting experiment. Much of the goodness of haskell, but with a much tighter focus and smaller scope. No imports, language pragmas, packages or build tools needed; all of the building blocks listed on one short page, https://chrisdone.github.io/hell/api https://chrisdone.github.io/hell/api. More platform independent, robust, and regular than shell. Potentially a nice learning language / stepping stone to haskell itself. It's quite verbose right now, and I don't see much networking API yet, but it's just starting. I could see it easily growing into something very nice.
metadat 2y ago
Why are there no examples with "#!/usr/bin/env ghc" at the top? It's not a shell script without the Linux incantation stanza.. for reals. How are you going to get started without the proper boiler plate?
- whateveracct 2y ago
  It's "#!/usr/bin/env hell" - this isn't ghc. See https://chrisdone.com/posts/hell/ https://chrisdone.com/posts/hell/ This seems to be a deep tour of the implementation as much as the language. So it's not supposed to be a first principles talk. That's fine. It's not all for everybody.
- hi-v-rocknroll 2y ago
  #!/usr/bin/env runhaskell ^ Works just fine. No need to reinvent what already exists and blog throwing shade on an inability to learn shell scripting.
- nine_k 2y ago
  (Ideally it should be #!/usr/bin/env descend, to folloe the style.)
scythmic_waves 2y ago
I bet reddit.com/r/ProgrammingLanguages/ would like this.
chubot 2y ago
FWIW there are several Haskell and OCaml shell projects on this wiki page, which is editable: Internal DSLs for Shell - https://github.com/oils-for-unix/oils/wiki/Internal-DSLs-for-Shell https://github.com/oils-for-unix/oils/wiki/Internal-DSLs-for... and ones in many other languages like Scheme and Lisp e.g. https://github.com/jgoerzen/hsh/wiki https://github.com/jgoerzen/hsh/wiki https://github.com/luke-clifton/shh/tree/master/shh https://github.com/luke-clifton/shh/tree/master/shh And also a page of alternative shells: https://github.com/oils-for-unix/oils/wiki/Alternative-Shells https://github.com/oils-for-unix/oils/wiki/Alternative-Shell...
- musha68k 2y ago
  Good reminders; just not readily seeing Babashka (Clojure through GraalVM) so mentioning here for sake of sexp closure. https://github.com/babashka/babashka https://github.com/babashka/babashka
bubblyworld 2y ago
For those like me who want to see actual examples of Hell scripts: https://chrisdone.github.io/hell/examples/ https://chrisdone.github.io/hell/examples/
pyuser583 2y ago
I love these names!

139 points by kreyenborgi 2y ago

I've wanted many things from shell but never to write Haskell in Shell. This turned something relatively naturally expressible into something so complex that requires type theory

sinkasapa 2y ago
There is no reason why one has to enjoy a haskell-like syntax over Bourne shell syntax but I think you're wrong about the tool. The author states that "It should have no abstraction capabilities (classes, data types, polymorphic functions, etc.)." Granted, there may be types but without those abstractions, I don't think you need to know much of anything about type theory.
eru 2y ago
You could use the Scheme Shell instead, if you don't like static typing. https://en.wikipedia.org/wiki/Scsh https://en.wikipedia.org/wiki/Scsh And specifically https://en.wikipedia.org/wiki/Scsh#%22Acknowledgments%22 https://en.wikipedia.org/wiki/Scsh#%22Acknowledgments%22

jonotime 2y ago

How was this page generated? I have a marp presentation (https://github.com/jonocodes/awesome-keyboards https://github.com/jonocodes/awesome-keyboards) that I would like to have shown on a single page like this with the notes expanded.

cryptonector 2y ago
I really like this page, with slides on the left and blog on the right.

chongli 2y ago

Interesting but not a great piece for anyone not into functional language design. A pretty deep dive into the "how" while completely ignoring the "why."

rwmj 2y ago
Or indeed the "what". Did he ever show an example of what the shell scripts look like? I couldn't see it.
- simonmic 2y ago
  The first link takes you to the home page, which links to examples; probably a better starting point. https://chrisdone.github.io/hell https://chrisdone.github.io/hell
  - rwmj 2y ago
    If you're giving a presentation, you should start by telling the audience what it is you're talking about. Someone in the audience won't have a clue, and usually most of the audience have no clue.
tmoertel 2y ago
Chris discusses the rationale in his blog post at https://chrisdone.com/posts/hell/ https://chrisdone.com/posts/hell/
- chongli 2y ago
  Thanks for this! I read that but I'm still not convinced. Quote: They lean far too heavily on sub processes to do basic things. I thought this was the whole point of a unix scripting language! Most of the scripts I'm writing are not interactive REPLs or string-parsers, they're glue code for batch-invoking commands on files. Stuff like converting a bunch of FLAC files into MP3 with lame or avi video files into mkv with ffmpeg. What bash offers me is very terse command invocation and powerful filename globbing, including regexp substitution. Scripts like this are generally not intended to be used more than once or twice, and so a type system like Haskell provides is irrelevant here. If you're writing something that's going to be iterated on and maintained for years then you're writing an application, not a script.

simonmic 2y ago

As a haskeller, and shell scripter, I find this a refreshing and exciting experiment. Much of the goodness of haskell, but with a much tighter focus and smaller scope. No imports, language pragmas, packages or build tools needed; all of the building blocks listed on one short page, https://chrisdone.github.io/hell/api https://chrisdone.github.io/hell/api. More platform independent, robust, and regular than shell. Potentially a nice learning language / stepping stone to haskell itself. It's quite verbose right now, and I don't see much networking API yet, but it's just starting. I could see it easily growing into something very nice.

metadat 2y ago

Why are there no examples with "#!/usr/bin/env ghc" at the top? It's not a shell script without the Linux incantation stanza.. for reals. How are you going to get started without the proper boiler plate?

whateveracct 2y ago
It's "#!/usr/bin/env hell" - this isn't ghc. See https://chrisdone.com/posts/hell/ https://chrisdone.com/posts/hell/ This seems to be a deep tour of the implementation as much as the language. So it's not supposed to be a first principles talk. That's fine. It's not all for everybody.
hi-v-rocknroll 2y ago
#!/usr/bin/env runhaskell ^ Works just fine. No need to reinvent what already exists and blog throwing shade on an inability to learn shell scripting.
nine_k 2y ago
(Ideally it should be #!/usr/bin/env descend, to folloe the style.)

scythmic_waves 2y ago

I bet reddit.com/r/ProgrammingLanguages/ would like this.

chubot 2y ago

FWIW there are several Haskell and OCaml shell projects on this wiki page, which is editable: Internal DSLs for Shell - https://github.com/oils-for-unix/oils/wiki/Internal-DSLs-for-Shell https://github.com/oils-for-unix/oils/wiki/Internal-DSLs-for... and ones in many other languages like Scheme and Lisp e.g. https://github.com/jgoerzen/hsh/wiki https://github.com/jgoerzen/hsh/wiki https://github.com/luke-clifton/shh/tree/master/shh https://github.com/luke-clifton/shh/tree/master/shh And also a page of alternative shells: https://github.com/oils-for-unix/oils/wiki/Alternative-Shells https://github.com/oils-for-unix/oils/wiki/Alternative-Shell...

musha68k 2y ago
Good reminders; just not readily seeing Babashka (Clojure through GraalVM) so mentioning here for sake of sexp closure. https://github.com/babashka/babashka https://github.com/babashka/babashka

bubblyworld 2y ago

For those like me who want to see actual examples of Hell scripts: https://chrisdone.github.io/hell/examples/ https://chrisdone.github.io/hell/examples/

pyuser583 2y ago

I love these names!