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> Maelstrom is a Clojure program I was interested in trying this out, but why closure?

spockz 3y ago
I suppose because Jepsen is written in Clojure. And that is probably because the author was versed in Clojure and that is the language he picked.
whalesalad 3y ago
At the end of the day a Clojure program is a .jar file. You can write your systems in any language and this will command them. But Clojure is a very cool language worth exploring.
shaunxcode 3y ago
Why do astronauts wear space suits?
- namtab00 3y ago
  because they need 1atm of pressure to not have their liquids boil?
  - kubanczyk 3y ago
    If they were at 1atm, they would have really bad mobility. As an experiment I'd inflate a tire to 1atm and try to bend/stretch it by hand.
    - namtab00 3y ago
      AFAIK, space suits are not inflated, they are pressurized. Mobility is done with mechanical joints, not sheer bending force of an inflated chamber.
      - kubanczyk 3y ago
        They are semi-rigid (not hard shell) and kept to the minimum pressure allowed by human physiology (~0.3 atm, not 1 atm): https://en.wikipedia.org/wiki/Space_suit#Design_concepts https://en.wikipedia.org/wiki/Space_suit#Design_concepts
- ranting-moth 3y ago
  Well, if they wore no space suits they would have no space.
pluto_modadic 3y ago
I feel this in my newcomer bones. Every time someone badass writes something in erlang or clojure or rust or something and I'm like... "the problem was complicated enough, why'd you add an esoteric language to it?"
- simongray 3y ago
  Your answer: https://aphyr.com/posts/367-why-is-jepsen-written-in-clojure https://aphyr.com/posts/367-why-is-jepsen-written-in-clojure
- cultofmetatron 3y ago
  if you're writing a distributed language, clojure and erlang both have much better primitives for expressing solutions in that problem space.
- simongray 3y ago
  Why does this even matter to you? You're not forced to use Clojure to use this.
- unrealhoang 3y ago
  Why don't you think it's because of the tools those languages provide that helps them with the complicated problem?
- capableweb 3y ago
  Every time I see something implemented in a non-lisp language I'm like "the problem was complicated enough, why did you have to introduce a bunch of accidental complexity?!" Then I remember that everyone's brain works differently, and that's ok :)
FiberBundle 3y ago
Slightly off-topic, but I have worked with another tool by the author (Jepsen), which is also written in Clojure and in fact a Clojure library. I'm fairly proficient with functional programming in general, but had never touched Clojure before. My experience working with Jepsen was quite frustrating simply because of the fact that it's a Clojure library. Clojure is dynamically typed and it happened fairly frequently that I had to dig into Jepsen's source code simply because some type errors were only caught very deep in the call stack. Jepsen itself is a really great tool and I'm a very big fan of it's creator (Kyle Kingsbury), but the fact that you can only use it through Clojure is kind of sad. I guess it gets better with more clojure experience, but a dynamically typed functional programming language is kind of too much of design flaw for me to want to invest more time in the language.
- capableweb 3y ago
  > but the fact that you can only use it through Clojure is kind of sad You can use Clojure stuff from Java, if you really want to: https://clojure.org/reference/java_interop#_calling_clojure_from_java https://clojure.org/reference/java_interop#_calling_clojure_... > but a dynamically typed functional programming language is kind of too much of design flaw for me And for others it's the opposite. Unless the language have good primitives for distributed computing and is a functional and dynamic language, it's usually not worth spending the time to learn it, for me at least. Good thing there is at least one language out there for everyone, so we have choices :)
aphyr 3y ago
Maelstrom is a frontend to Jepsen, a Clojure library for testing concurrent systems--mostly databases. Jepsen is also written in Clojure and Java--both run on the JVM. Because it tests concurrent systems, the language itself needs good support for concurrency. Clojure's persistent data structures make it easier to write correct concurrent programs, and the language and runtime have excellent concurrency support. I also considered languages (like Haskell) with more rigorous control over side effects, but decided that Clojure's less-dogmatic approach was preferable. Because Jepsen tests databases, it needs broad client support. Almost every database has a JVM client, and Clojure has decent Java interop. Because testing is experimental work, I needed a language which was concise, adaptable, and well-suited to prototyping. Clojure's concision and syntactic flexibility work well for that. Tests involve representing, transforming, and inspecting complex, nested data structures. Clojure's data structures and standard library functions are possibly the best I've ever seen. I also print a lot of structures to the console and files: Clojure's data syntax (EDN) is fantastic for this. Because tests involve manipulating a decent, but not huge, chunk of data, I needed a language with "good enough" performance. Clojure's certainly not the fastest language out there, but idiomatic Clojure is usually within an order of magnitude or two of Java, and I can shave off the difference where critical. The JVM has excellent profiling tools, and these work well with Clojure. Jepsen's (gosh) about a decade old now: I wanted a language with a mature core and emphasis on stability. Clojure is remarkably stable, both in terms of JVM target and the language itself. Libraries don't "rot" anywhere near as quickly as in Scala or Ruby. Clojure does have significant drawbacks. It has a small engineering community and no (broadly-accepted, successful) static typing system. Both of these would constrain a large team, but Jepsen's maintained and used by only 1-3 people at a time. Working with JVM primitives can be frustrating without dropping to Java; I do this on occasion. Some aspects of the polymorphism system are lacking, but these can be worked around with libraries. The error messages are terrible. I have no apologetics for this. ;-) I prototyped Jepsen in a few different languages before settling on Clojure. A decade in, I think it was a pretty good tradeoff.

I suppose because Jepsen is written in Clojure. And that is probably because the author was versed in Clojure and that is the language he picked.

whalesalad 3y ago

At the end of the day a Clojure program is a .jar file. You can write your systems in any language and this will command them. But Clojure is a very cool language worth exploring.

shaunxcode 3y ago

Why do astronauts wear space suits?

namtab00 3y ago
because they need 1atm of pressure to not have their liquids boil?
- kubanczyk 3y ago
  If they were at 1atm, they would have really bad mobility. As an experiment I'd inflate a tire to 1atm and try to bend/stretch it by hand.
  - namtab00 3y ago
    AFAIK, space suits are not inflated, they are pressurized. Mobility is done with mechanical joints, not sheer bending force of an inflated chamber.
    - kubanczyk 3y ago
      They are semi-rigid (not hard shell) and kept to the minimum pressure allowed by human physiology (~0.3 atm, not 1 atm): https://en.wikipedia.org/wiki/Space_suit#Design_concepts https://en.wikipedia.org/wiki/Space_suit#Design_concepts
ranting-moth 3y ago
Well, if they wore no space suits they would have no space.

pluto_modadic 3y ago

I feel this in my newcomer bones. Every time someone badass writes something in erlang or clojure or rust or something and I'm like... "the problem was complicated enough, why'd you add an esoteric language to it?"

simongray 3y ago
Your answer: https://aphyr.com/posts/367-why-is-jepsen-written-in-clojure https://aphyr.com/posts/367-why-is-jepsen-written-in-clojure
cultofmetatron 3y ago
if you're writing a distributed language, clojure and erlang both have much better primitives for expressing solutions in that problem space.
simongray 3y ago
Why does this even matter to you? You're not forced to use Clojure to use this.
unrealhoang 3y ago
Why don't you think it's because of the tools those languages provide that helps them with the complicated problem?
capableweb 3y ago
Every time I see something implemented in a non-lisp language I'm like "the problem was complicated enough, why did you have to introduce a bunch of accidental complexity?!" Then I remember that everyone's brain works differently, and that's ok :)

FiberBundle 3y ago

Slightly off-topic, but I have worked with another tool by the author (Jepsen), which is also written in Clojure and in fact a Clojure library. I'm fairly proficient with functional programming in general, but had never touched Clojure before. My experience working with Jepsen was quite frustrating simply because of the fact that it's a Clojure library. Clojure is dynamically typed and it happened fairly frequently that I had to dig into Jepsen's source code simply because some type errors were only caught very deep in the call stack. Jepsen itself is a really great tool and I'm a very big fan of it's creator (Kyle Kingsbury), but the fact that you can only use it through Clojure is kind of sad. I guess it gets better with more clojure experience, but a dynamically typed functional programming language is kind of too much of design flaw for me to want to invest more time in the language.

capableweb 3y ago
> but the fact that you can only use it through Clojure is kind of sad You can use Clojure stuff from Java, if you really want to: https://clojure.org/reference/java_interop#_calling_clojure_from_java https://clojure.org/reference/java_interop#_calling_clojure_... > but a dynamically typed functional programming language is kind of too much of design flaw for me And for others it's the opposite. Unless the language have good primitives for distributed computing and is a functional and dynamic language, it's usually not worth spending the time to learn it, for me at least. Good thing there is at least one language out there for everyone, so we have choices :)

aphyr 3y ago

Maelstrom is a frontend to Jepsen, a Clojure library for testing concurrent systems--mostly databases. Jepsen is also written in Clojure and Java--both run on the JVM. Because it tests concurrent systems, the language itself needs good support for concurrency. Clojure's persistent data structures make it easier to write correct concurrent programs, and the language and runtime have excellent concurrency support. I also considered languages (like Haskell) with more rigorous control over side effects, but decided that Clojure's less-dogmatic approach was preferable. Because Jepsen tests databases, it needs broad client support. Almost every database has a JVM client, and Clojure has decent Java interop. Because testing is experimental work, I needed a language which was concise, adaptable, and well-suited to prototyping. Clojure's concision and syntactic flexibility work well for that. Tests involve representing, transforming, and inspecting complex, nested data structures. Clojure's data structures and standard library functions are possibly the best I've ever seen. I also print a lot of structures to the console and files: Clojure's data syntax (EDN) is fantastic for this. Because tests involve manipulating a decent, but not huge, chunk of data, I needed a language with "good enough" performance. Clojure's certainly not the fastest language out there, but idiomatic Clojure is usually within an order of magnitude or two of Java, and I can shave off the difference where critical. The JVM has excellent profiling tools, and these work well with Clojure. Jepsen's (gosh) about a decade old now: I wanted a language with a mature core and emphasis on stability. Clojure is remarkably stable, both in terms of JVM target and the language itself. Libraries don't "rot" anywhere near as quickly as in Scala or Ruby. Clojure does have significant drawbacks. It has a small engineering community and no (broadly-accepted, successful) static typing system. Both of these would constrain a large team, but Jepsen's maintained and used by only 1-3 people at a time. Working with JVM primitives can be frustrating without dropping to Java; I do this on occasion. Some aspects of the polymorphism system are lacking, but these can be worked around with libraries. The error messages are terrible. I have no apologetics for this. ;-) I prototyped Jepsen in a few different languages before settling on Clojure. A decade in, I think it was a pretty good tradeoff.