351 karma · joined November 7, 2011
[1] https://github.com/datalevin/datalevin/tree/master/benchmark...
In any case, it is possible to write Clojure in a way that is type checked at compile time. And it is an acceptable way to write Clojure. I just want to clear the air.
You guys make it out like Clojure is doing something extra to hide Java types, but it doesn’t. What Clojure does is really minimal on top of Java. It barely hides anything.
If you give it type, it will check type. If you don’t give a type, it falls back to a default type, Object, which IS a TYPE. The fact that Clojure compiler cannot deal with GraalVM SVM Pointer type tells you that it’s checking type, because Pointer is not an Object! I found this out the hard way: https://yyhh.org/blog/2021/02/writing-c-code-in-javaclojure-...
“One limitation that one needs to be aware of when writing native image related Clojure code, is that most things in the GraalVM SDK inherit from org.graalvm.word.WordBase, not from java.lang.Object, which breaks the hidden assumption of a lot of Clojure constructs.”
Clojure gives you the option to run the compiler at runtime, so that's what people normally do. However, you can also run the compiler at compile time. Right?
For people who want type checking, they can opt to write Clojure in this defprotocol everywhere style, and turn on AOT. Then they basically get the same thing as what Java gives them.
As to example of libraries that are defprotocols everywhere, you should look at any of the low level performance minded libraries in the Clojure ecosystem, they are either written in this defprotocols everywhere style, such as nippy, neanderthal, dtype-next, and so on, or mostly in Java, such as http-kit, fast-edn, etc. I noticed this phenomenon, because my own libraries, editscript and datalevin, are written in this way. I take comfort that my fellow performance minded library authors are doing the same. Finally, isn't Clojurescript entirely driven by protocols?
So really, there are two kind of Clojure programmers. One type writes application code or high level libraries, and they write normal Clojure code all the time. However, there are also those who write primarily low level library code, which are used by the first camp, and their code is full of defprotocol and deftypes. So defprotocol everywhere is not anti-pattern. It's anti-pattern only in the mind of the first camp of programmers, and that's a narrow minded way of looking at things. Even the first version of Clojure Programming book by the core team members, are written in a way that's full of defrecord. Remember?
This "everything is a map" orthodoxy is turning people away from Clojure. Just let people write the code that suits their own needs. We can use more people who are pragmatic instead of dogmatic in the Clojure world. If you trust Rich Hickey's judgment, then you should trust him put in the features Clojure has for good reasons. Macros and protocols are part of the Clojure language, and you should be using them when the use case calls for them. Stop the "anti-pattern" nonsense.
So if you use defprotocol and deftype for every domain objects in your code, your code won't compile if there's a type error. Try it.
BTW, that's the way many Clojure libraries are implemented. These libraries rely on dispatch on type to work, so they are taking advantage of the type checking.
Of course, you will say, "oh, clojure is not normally AOT, so it's not dong the checks.", but that's another issue. The issue at hand is this: can you write Clojure such that types are checked at compile time. The answer is YES.
The compiler may run only when you run the program, that's a different issue. You are confusing these two issues.
If you want a separate compile stage, then basically you are already excluding runtime compilation, i.e. you are arguing against runtime compilation. So it's not really about typing, but about how you want to run the program. Isn't it? You want AOT for everything, you don't want runtime compilation. That's it. It has nothing to do with types.
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.
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.
As to databases, there are a fountain of databases emerging from the Clojure ecosystem: Datomic, Datascript, Datalevin, XTDB, and friends aside, there is Rama, which is a distributed database (or to replace database?)
Many people still use lein for new projects, especially for larger ones. For small on-off thing, clojure command line is more convenient. So it is a good thing to have more choices.
BTW, when Clojurians talk about REPL, it's not about that separate window where you type and run the code as in other language such as python. They are talking about an invisible REPL running behind the scene, to which they send code within their editors, and the results show up in the editors too.
There's no need to "miss static typing" in Clojure. If I need static typing, I just write deprotocol and deftype in Clojure, as many Clojure libraries do.
Immutable data pairs great with REPL.
Because data are immutable, you don't need to care about where that data come from and where it will go. Just focus on what you need to do with that data at the point you work.
Everything is localized due to immutability.
In many use cases, database is where application state resides, hence a mutable database is a better fit.
There are Datomic flavored database in the Clojure ecosystem that is specifically design to address this point, e.g. Datalevin.
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.
If you don't do what everybody is doing to solve a problem, then of course it is not a "solved problem" for you.
No, you don't need to code specifically for native-image. What are the landmines that you need to code around? Since you have not successfully compiled native-image by following common practices, you obviously don't know.