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For someone who needs static typing, Clojure give them defprotocol, deftype and defrecord. Interestingly, most of the low level libraries in the Clojure ecosys

For someone who needs static typing, Clojure give them defprotocol, deftype and defrecord. Interestingly, most of the low level libraries in the Clojure ecosystem are programmed that way. If you open up the code of many popular Clojure libraries, you see defprotocol everywhere. So really, Clojure does both: dynamic typing for application programming, mostly static typing for infrastructure library code. As they should be. This tired argument of "Clojure bad for dynamic typing" just doesn't hold water. Keep repeating it is a sign of lack of critical thinking.

yogthos 2y ago
I'd argue defprotocol, deftype, and defrecord provide much weaker guarantees than a type system. Dtuff like defprotocol tends to serve a similar use case to using an interface in Java. You specify the signatures for the functions, and then a concrete implementation can be provided using a library. Ring servers are a good example of this where you can easily plug different server implementations by just swapping a library. There is Typed Clojure https://typedclojure.org/ https://typedclojure.org/ for people who want actual static typing, but the fact that it never caught on suggests this wasn't a real pain point for most people using Clojure. As other people mentioned, immutability tend to be a more important feature than static types because it makes it easy to write code that's referentially transparent. You can structure your whole application as a series of small components that can be reasoned about in isolation.
- huahaiy 2y ago
  Nobody would argue that Java is not statically typed. That's my point. Clojure offers the same as what Java offers. If you write code in a defprotocol everywhere style, as many Clojure libraries do, your code won't compile if you got the types wrong. The same as Java. How's that not static typing? Which part of that is weaker? So what exactly this "Clojure dynamic typing" nonsense is about, I fail to see. Automatically inferred type system is not the same thing as static typing. Typed Clojure is the former. Typed Clojure did not catch on, but static typing style of Clojure did, as many Clojure libraries do exactly that: internally, defprotocal everywhere, externally, some Clojure functions to give the illusion of normal Clojure code. BTW, that's the style how Clojure itself is written in as well.
  - mrkeen 2y ago
    > If you write code in a defprotocol everywhere style, as many Clojure libraries do, your code won't compile if you got the types wrong. The same as Java. How's that not static typing? Which part of that is weaker? > So what exactly this "Clojure dynamic typing" nonsense is about, I fail to see. No-one has the time to learn all these languages, so for those of us not in the know, the most generous we can be is to take these praise articles at face value. And these articles are typically 'dynamic good', 'static bad'. From the article: they insist on a statically typed worldview leading to parochial, snowflake APIs that defy abstraction and higher level manipulation, or both. So I guess the user base for this language is those developers who think dynamic is better than static, and go for (as-static-as-Java) Closure.
    - ugaibugai 2y ago
      The part of code not compiling got me interested. Do you happen to have an example or tutorial about this?
  - yogthos 2y ago
    That's not quite true though. Java tracks types in the signatures of the functions, defprotocol does not. If I make a protocol and then pass a wrong type as a parameter to it then I'll get a runtime error. It's not going to tell me that I passed in a wrong type at compile time. I find using defprotocol in Clojure tends to be an antipattern because it just makes code harder to read by introducing indirection. The libraries using defprotocol use it to solve a specific problem of creating a contract for how the API looks.
    - huahaiy 2y ago
      Then you are not writing in defprotocol everywhere style. The keyword is everywhere. All the domain objects are deftype or defrecord. Try that. It is the same as Java, basically. It is not an anti pattern, it is the way most low level libraries and clojure itself are written. Clojure is a tool, not a cult. This core team worship is turning people away. The core team made plenty of mistakes, and got called out, rightfully.

yogthos 2y ago

I'd argue defprotocol, deftype, and defrecord provide much weaker guarantees than a type system. Dtuff like defprotocol tends to serve a similar use case to using an interface in Java. You specify the signatures for the functions, and then a concrete implementation can be provided using a library. Ring servers are a good example of this where you can easily plug different server implementations by just swapping a library. There is Typed Clojure https://typedclojure.org/ https://typedclojure.org/ for people who want actual static typing, but the fact that it never caught on suggests this wasn't a real pain point for most people using Clojure. As other people mentioned, immutability tend to be a more important feature than static types because it makes it easy to write code that's referentially transparent. You can structure your whole application as a series of small components that can be reasoned about in isolation.

huahaiy 2y ago
Nobody would argue that Java is not statically typed. That's my point. Clojure offers the same as what Java offers. If you write code in a defprotocol everywhere style, as many Clojure libraries do, your code won't compile if you got the types wrong. The same as Java. How's that not static typing? Which part of that is weaker? So what exactly this "Clojure dynamic typing" nonsense is about, I fail to see. Automatically inferred type system is not the same thing as static typing. Typed Clojure is the former. Typed Clojure did not catch on, but static typing style of Clojure did, as many Clojure libraries do exactly that: internally, defprotocal everywhere, externally, some Clojure functions to give the illusion of normal Clojure code. BTW, that's the style how Clojure itself is written in as well.
- mrkeen 2y ago
  > If you write code in a defprotocol everywhere style, as many Clojure libraries do, your code won't compile if you got the types wrong. The same as Java. How's that not static typing? Which part of that is weaker? > So what exactly this "Clojure dynamic typing" nonsense is about, I fail to see. No-one has the time to learn all these languages, so for those of us not in the know, the most generous we can be is to take these praise articles at face value. And these articles are typically 'dynamic good', 'static bad'. From the article: they insist on a statically typed worldview leading to parochial, snowflake APIs that defy abstraction and higher level manipulation, or both. So I guess the user base for this language is those developers who think dynamic is better than static, and go for (as-static-as-Java) Closure.
  - ugaibugai 2y ago
    The part of code not compiling got me interested. Do you happen to have an example or tutorial about this?
- yogthos 2y ago
  That's not quite true though. Java tracks types in the signatures of the functions, defprotocol does not. If I make a protocol and then pass a wrong type as a parameter to it then I'll get a runtime error. It's not going to tell me that I passed in a wrong type at compile time. I find using defprotocol in Clojure tends to be an antipattern because it just makes code harder to read by introducing indirection. The libraries using defprotocol use it to solve a specific problem of creating a contract for how the API looks.
  - huahaiy 2y ago
    Then you are not writing in defprotocol everywhere style. The keyword is everywhere. All the domain objects are deftype or defrecord. Try that. It is the same as Java, basically. It is not an anti pattern, it is the way most low level libraries and clojure itself are written. Clojure is a tool, not a cult. This core team worship is turning people away. The core team made plenty of mistakes, and got called out, rightfully.