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I don't the author really gave Ocaml a chance. He argues that every language needs to have interfaces. I agree somewhat with that statement, but I think the tru

I don't the author really gave Ocaml a chance. He argues that every language needs to have interfaces. I agree somewhat with that statement, but I think the truer statement is to say that every language needs to have some way of defining composition at a structural level. An interface allows you to pass different "structures" to the same function so long as they adhere to the same spec. In Ocaml this is accomplished through modules, functors, and module signatures. Ocaml's module signature can play the same exact role as interfaces in Haskell, Rust or F#. The module system is arguably more expressive than what can be accomplished to interfaces. To give an example, Ocaml suffers from the same problem as rust does with having two standard implementations of a async runtime. Just like rusts: tokio and async-std, ocaml has Lwt, Async, (and newly added to the mix Eio). Whereas in rust most libraries just implement one of these systems, and you'll have to use compiler directives to support both. Ocaml's module system means that you can describe the async runtime as a signature and make your entire library generic to the async runtime it runs on top of. Most of the well-used libraries do this, and so you don't have to worry too much about which runtime you decide to use. Clearly, a language that can do that must have in some place a system that can replace interfaces.

boxed 3y ago
To me it seems he gave it a lot of chance in order to find this many problems. It does sound to me like you stopped reading after the first point. Maybe you didn't give the post a chance?
- spqr233 3y ago
  It's more that only really strongly disagreed with that point. Frankly, there are some cons with using Ocaml. In practice, I think the library support for ocaml isn't completely there given the small community.
- WastingMyTime89 3y ago
  To be honest, anyone who used Ocaml understands immediately that the author gave it no chance and went looking for problems. It’s obvious because the post lingers a lot about things which are not actually issues like type conversion but don’t talk about the very real issues Ocaml has (opam is not great, dune is weird).
  - hardwaregeek 3y ago
    Why are these things not issues? I think it's totally valid for someone who doesn't understand OCaml to raise issues of usability or documentation. It's not just the issues of experts that are a concern. And it's very demoralizing to get a "you're holding it wrong" response to a complaint.
    - WastingMyTime89 3y ago
      Because they are not issues on a day to day basis when you use the language. I used Ocaml for a paid internship some years ago. I was very much a beginner. Do you know how many time I felt at loss or annoyed by type conversion or the precedence rules for various part of the syntax? I never did. The truth is you never encounter the precedence rules when writing Ocaml normally using parentheses like a normal human being and you don’t convert that much between exotic types. Most of the conversion you actually do are between the same types and most of the time you have to write converter anyway because there is logic involved. I worked professionally as a Java developer for a bit. I think I had to write more conversion code between weird classes then than I ever did in Ocaml. The issue is not telling people they are "holding it wrong". The issue is that this is not what’s going to annoy you as an Ocaml beginner. The author of this article is not even an Ocaml beginner by the way. That’s actually someone who used to work on the Haskell compiler.
      - ModernMech 3y ago
        > The issue is that this is not what’s going to annoy you as an Ocaml beginner. Sure, but tbf, the post is about what annoys the author, not what would annoy beginners. As you say, the author is not a beginner, and so their problems wouldn't be beginner problems.
        WastingMyTime89 3y ago
        That’s not the point I was making. They are not expert problems either. How often as an expert do you think you encounter precedence issues you were not encountering as a beginner?
actionfromafar 3y ago
> Ocaml's module system means that you can describe the async runtime as a signature and make your entire library generic to the async runtime it runs on top of So ... can you ELI5 to me how that is different from how you can for instance compile a C program against different libc implementations?
- kajaktum 3y ago
  I mean…you can technically have a function that take void* and return void* be the interface. But you wouldn’t be able to represent things like iterator and chain them together without care. In C you would be tripping all over the slight details like forgetting to check errno or something.
  - actionfromafar 3y ago
    So, it's like C++20 then?
v0idzer0 3y ago
Came here to make this exact point. But I totally agree with all of his other complaints. It’s a good list of the cons, but ignored the many pros
hardwaregeek 3y ago
Politely, I feel like this is the issue with OCaml as a community. You gave a beautiful answer about programming language design and composition. But how does it feel to write the language? How can you print a user defined data type? From reading around, it seems like your options are: explicitly pass a print function for that specific type, use a third party library for printing, or (my "favorite") don't. Or how does it feel to write a function that takes a generic that can be printed, checked for equality, and read? Or to convert one type into another type? And we're still talking about semantics here. How does it feel to use the language server? How does it feel to read the code? To build the language? Ultimately that's what users judge a language on. Yes, Rust in some ways has a worse form of abstraction. It is global, not fully generic and doesn't allow for overloading. But it creates a user experience that is nicer. It lets a user print something and compare two variables and do type conversions without having to scratch their head, read a forum post and import a library.
- yodsanklai 3y ago
  > How can you print a user defined data type? Pretty much the same way you'd do in Haskell or Rust: you add a `[@@deriving show]` directive to your datatype.
- ywei3410 3y ago
  > You gave a beautiful answer about programming language You do the same thing as in Rust, Scala or Haskell and derive the printer [1]. Then at the callsite, if you know the type then you do `T.show` to print it or `T.eq`. If you don't know the type, then you pass it in at the top level as a module and then do `T.show` or `T.eq`. > Or to convert one type into another type? If you want to convert a type, then you have a type that you want to convert from such as foo and bar, then you do `Foo.to_bar value`. We can keep going, but you can get the point. You _can't_ judge a language by doing what you want to do with one language in another. If I judge Rust by writing recursive data structures and complaining about performance and verbosity that's not particularly fair correct? I can't say that Dart is terrible for desktop because I can't use chrome developer tools on its canvas output and ignore it's hot-reloading server. I can't say Common Lisp code is unreadable because I don't have type annotations and ignore the REPL for introspection. [1] https://github.com/ocaml-ppx/ppx_deriving https://github.com/ocaml-ppx/ppx_deriving
maleldil 3y ago
> Ocaml's module system means that you can describe the async runtime as a signature and make your entire library generic to the async runtime it runs on top of Is this the program describing the interface it expects, and the compiler matching that with the implementations structure (e.g. Go interfaces, Python Protocols), or is it something someone declares and the libraries implement?
- yawaramin 3y ago
  Mostly the former. The compiler infers the type of the implementation and ensures it conforms to the interface. But, you can further restrict the interface's type to hide details from the outside world.

boxed 3y ago

To me it seems he gave it a lot of chance in order to find this many problems. It does sound to me like you stopped reading after the first point. Maybe you didn't give the post a chance?

spqr233 3y ago
It's more that only really strongly disagreed with that point. Frankly, there are some cons with using Ocaml. In practice, I think the library support for ocaml isn't completely there given the small community.
WastingMyTime89 3y ago
To be honest, anyone who used Ocaml understands immediately that the author gave it no chance and went looking for problems. It’s obvious because the post lingers a lot about things which are not actually issues like type conversion but don’t talk about the very real issues Ocaml has (opam is not great, dune is weird).
- hardwaregeek 3y ago
  Why are these things not issues? I think it's totally valid for someone who doesn't understand OCaml to raise issues of usability or documentation. It's not just the issues of experts that are a concern. And it's very demoralizing to get a "you're holding it wrong" response to a complaint.
  - WastingMyTime89 3y ago
    Because they are not issues on a day to day basis when you use the language. I used Ocaml for a paid internship some years ago. I was very much a beginner. Do you know how many time I felt at loss or annoyed by type conversion or the precedence rules for various part of the syntax? I never did. The truth is you never encounter the precedence rules when writing Ocaml normally using parentheses like a normal human being and you don’t convert that much between exotic types. Most of the conversion you actually do are between the same types and most of the time you have to write converter anyway because there is logic involved. I worked professionally as a Java developer for a bit. I think I had to write more conversion code between weird classes then than I ever did in Ocaml. The issue is not telling people they are "holding it wrong". The issue is that this is not what’s going to annoy you as an Ocaml beginner. The author of this article is not even an Ocaml beginner by the way. That’s actually someone who used to work on the Haskell compiler.
    - ModernMech 3y ago
      > The issue is that this is not what’s going to annoy you as an Ocaml beginner. Sure, but tbf, the post is about what annoys the author, not what would annoy beginners. As you say, the author is not a beginner, and so their problems wouldn't be beginner problems.
      - WastingMyTime89 3y ago
        That’s not the point I was making. They are not expert problems either. How often as an expert do you think you encounter precedence issues you were not encountering as a beginner?

actionfromafar 3y ago

> Ocaml's module system means that you can describe the async runtime as a signature and make your entire library generic to the async runtime it runs on top of So ... can you ELI5 to me how that is different from how you can for instance compile a C program against different libc implementations?

kajaktum 3y ago
I mean…you can technically have a function that take void* and return void* be the interface. But you wouldn’t be able to represent things like iterator and chain them together without care. In C you would be tripping all over the slight details like forgetting to check errno or something.
- actionfromafar 3y ago
  So, it's like C++20 then?

v0idzer0 3y ago

Came here to make this exact point. But I totally agree with all of his other complaints. It’s a good list of the cons, but ignored the many pros

hardwaregeek 3y ago

Politely, I feel like this is the issue with OCaml as a community. You gave a beautiful answer about programming language design and composition. But how does it feel to write the language? How can you print a user defined data type? From reading around, it seems like your options are: explicitly pass a print function for that specific type, use a third party library for printing, or (my "favorite") don't. Or how does it feel to write a function that takes a generic that can be printed, checked for equality, and read? Or to convert one type into another type? And we're still talking about semantics here. How does it feel to use the language server? How does it feel to read the code? To build the language? Ultimately that's what users judge a language on. Yes, Rust in some ways has a worse form of abstraction. It is global, not fully generic and doesn't allow for overloading. But it creates a user experience that is nicer. It lets a user print something and compare two variables and do type conversions without having to scratch their head, read a forum post and import a library.

yodsanklai 3y ago
> How can you print a user defined data type? Pretty much the same way you'd do in Haskell or Rust: you add a `[@@deriving show]` directive to your datatype.
ywei3410 3y ago
> You gave a beautiful answer about programming language You do the same thing as in Rust, Scala or Haskell and derive the printer [1]. Then at the callsite, if you know the type then you do `T.show` to print it or `T.eq`. If you don't know the type, then you pass it in at the top level as a module and then do `T.show` or `T.eq`. > Or to convert one type into another type? If you want to convert a type, then you have a type that you want to convert from such as foo and bar, then you do `Foo.to_bar value`. We can keep going, but you can get the point. You _can't_ judge a language by doing what you want to do with one language in another. If I judge Rust by writing recursive data structures and complaining about performance and verbosity that's not particularly fair correct? I can't say that Dart is terrible for desktop because I can't use chrome developer tools on its canvas output and ignore it's hot-reloading server. I can't say Common Lisp code is unreadable because I don't have type annotations and ignore the REPL for introspection. [1] https://github.com/ocaml-ppx/ppx_deriving https://github.com/ocaml-ppx/ppx_deriving

maleldil 3y ago

> Ocaml's module system means that you can describe the async runtime as a signature and make your entire library generic to the async runtime it runs on top of Is this the program describing the interface it expects, and the compiler matching that with the implementations structure (e.g. Go interfaces, Python Protocols), or is it something someone declares and the libraries implement?

yawaramin 3y ago
Mostly the former. The compiler infers the type of the implementation and ensures it conforms to the interface. But, you can further restrict the interface's type to hide details from the outside world.